5661 lines
152 KiB
C
5661 lines
152 KiB
C
/*
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* Generic process-grouping system.
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*
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* Based originally on the cpuset system, extracted by Paul Menage
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* Copyright (C) 2006 Google, Inc
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*
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* Notifications support
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* Copyright (C) 2009 Nokia Corporation
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* Author: Kirill A. Shutemov
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*
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* Copyright notices from the original cpuset code:
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* --------------------------------------------------
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* Copyright (C) 2003 BULL SA.
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* Copyright (C) 2004-2006 Silicon Graphics, Inc.
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*
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* Portions derived from Patrick Mochel's sysfs code.
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* sysfs is Copyright (c) 2001-3 Patrick Mochel
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*
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* 2003-10-10 Written by Simon Derr.
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* 2003-10-22 Updates by Stephen Hemminger.
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* 2004 May-July Rework by Paul Jackson.
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* ---------------------------------------------------
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of the Linux
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* distribution for more details.
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*/
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#include <linux/cgroup.h>
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#include <linux/cred.h>
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#include <linux/ctype.h>
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#include <linux/errno.h>
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#include <linux/init_task.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/proc_fs.h>
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#include <linux/rcupdate.h>
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#include <linux/sched.h>
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#include <linux/backing-dev.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/magic.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/sort.h>
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#include <linux/kmod.h>
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#include <linux/module.h>
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#include <linux/delayacct.h>
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#include <linux/cgroupstats.h>
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#include <linux/hashtable.h>
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#include <linux/namei.h>
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#include <linux/pid_namespace.h>
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#include <linux/idr.h>
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#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
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#include <linux/eventfd.h>
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#include <linux/poll.h>
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#include <linux/flex_array.h> /* used in cgroup_attach_task */
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#include <linux/kthread.h>
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#include <linux/atomic.h>
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/*
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* cgroup_mutex is the master lock. Any modification to cgroup or its
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* hierarchy must be performed while holding it.
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*
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* cgroup_root_mutex nests inside cgroup_mutex and should be held to modify
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* cgroupfs_root of any cgroup hierarchy - subsys list, flags,
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* release_agent_path and so on. Modifying requires both cgroup_mutex and
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* cgroup_root_mutex. Readers can acquire either of the two. This is to
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* break the following locking order cycle.
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*
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* A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem
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* B. namespace_sem -> cgroup_mutex
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*
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* B happens only through cgroup_show_options() and using cgroup_root_mutex
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* breaks it.
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*/
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#ifdef CONFIG_PROVE_RCU
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DEFINE_MUTEX(cgroup_mutex);
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EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for task_subsys_state_check() */
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#else
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static DEFINE_MUTEX(cgroup_mutex);
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#endif
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static DEFINE_MUTEX(cgroup_root_mutex);
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/*
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* Generate an array of cgroup subsystem pointers. At boot time, this is
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* populated with the built in subsystems, and modular subsystems are
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* registered after that. The mutable section of this array is protected by
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* cgroup_mutex.
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*/
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#define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys,
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#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
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static struct cgroup_subsys *cgroup_subsys[CGROUP_SUBSYS_COUNT] = {
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#include <linux/cgroup_subsys.h>
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};
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/*
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* The dummy hierarchy, reserved for the subsystems that are otherwise
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* unattached - it never has more than a single cgroup, and all tasks are
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* part of that cgroup.
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*/
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static struct cgroupfs_root cgroup_dummy_root;
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/* dummy_top is a shorthand for the dummy hierarchy's top cgroup */
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static struct cgroup * const cgroup_dummy_top = &cgroup_dummy_root.top_cgroup;
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/*
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* cgroupfs file entry, pointed to from leaf dentry->d_fsdata.
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*/
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struct cfent {
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struct list_head node;
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struct dentry *dentry;
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struct cftype *type;
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/* file xattrs */
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struct simple_xattrs xattrs;
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};
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/*
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* CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
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* cgroup_subsys->use_id != 0.
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*/
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#define CSS_ID_MAX (65535)
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struct css_id {
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/*
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* The css to which this ID points. This pointer is set to valid value
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* after cgroup is populated. If cgroup is removed, this will be NULL.
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* This pointer is expected to be RCU-safe because destroy()
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* is called after synchronize_rcu(). But for safe use, css_tryget()
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* should be used for avoiding race.
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*/
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struct cgroup_subsys_state __rcu *css;
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/*
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* ID of this css.
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*/
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unsigned short id;
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/*
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* Depth in hierarchy which this ID belongs to.
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*/
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unsigned short depth;
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/*
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* ID is freed by RCU. (and lookup routine is RCU safe.)
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*/
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struct rcu_head rcu_head;
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/*
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* Hierarchy of CSS ID belongs to.
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*/
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unsigned short stack[0]; /* Array of Length (depth+1) */
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};
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/*
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* cgroup_event represents events which userspace want to receive.
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*/
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struct cgroup_event {
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/*
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* Cgroup which the event belongs to.
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*/
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struct cgroup *cgrp;
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/*
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* Control file which the event associated.
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*/
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struct cftype *cft;
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/*
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* eventfd to signal userspace about the event.
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*/
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struct eventfd_ctx *eventfd;
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/*
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* Each of these stored in a list by the cgroup.
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*/
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struct list_head list;
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/*
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* All fields below needed to unregister event when
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* userspace closes eventfd.
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*/
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poll_table pt;
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wait_queue_head_t *wqh;
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wait_queue_t wait;
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struct work_struct remove;
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};
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/* The list of hierarchy roots */
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static LIST_HEAD(cgroup_roots);
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static int cgroup_root_count;
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/*
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* Hierarchy ID allocation and mapping. It follows the same exclusion
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* rules as other root ops - both cgroup_mutex and cgroup_root_mutex for
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* writes, either for reads.
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*/
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static DEFINE_IDR(cgroup_hierarchy_idr);
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static struct cgroup_name root_cgroup_name = { .name = "/" };
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/*
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* Assign a monotonically increasing serial number to cgroups. It
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* guarantees cgroups with bigger numbers are newer than those with smaller
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* numbers. Also, as cgroups are always appended to the parent's
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* ->children list, it guarantees that sibling cgroups are always sorted in
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* the ascending serial number order on the list. Protected by
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* cgroup_mutex.
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*/
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static u64 cgroup_serial_nr_next = 1;
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/* This flag indicates whether tasks in the fork and exit paths should
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* check for fork/exit handlers to call. This avoids us having to do
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* extra work in the fork/exit path if none of the subsystems need to
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* be called.
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*/
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static int need_forkexit_callback __read_mostly;
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static void cgroup_offline_fn(struct work_struct *work);
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static int cgroup_destroy_locked(struct cgroup *cgrp);
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static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
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struct cftype cfts[], bool is_add);
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/* convenient tests for these bits */
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static inline bool cgroup_is_dead(const struct cgroup *cgrp)
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{
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return test_bit(CGRP_DEAD, &cgrp->flags);
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}
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/**
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* cgroup_is_descendant - test ancestry
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* @cgrp: the cgroup to be tested
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* @ancestor: possible ancestor of @cgrp
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*
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* Test whether @cgrp is a descendant of @ancestor. It also returns %true
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* if @cgrp == @ancestor. This function is safe to call as long as @cgrp
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* and @ancestor are accessible.
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*/
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bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor)
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{
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while (cgrp) {
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if (cgrp == ancestor)
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return true;
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cgrp = cgrp->parent;
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}
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return false;
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}
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EXPORT_SYMBOL_GPL(cgroup_is_descendant);
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static int cgroup_is_releasable(const struct cgroup *cgrp)
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{
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const int bits =
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(1 << CGRP_RELEASABLE) |
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(1 << CGRP_NOTIFY_ON_RELEASE);
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return (cgrp->flags & bits) == bits;
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}
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static int notify_on_release(const struct cgroup *cgrp)
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{
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return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
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}
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/**
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* for_each_subsys - iterate all loaded cgroup subsystems
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* @ss: the iteration cursor
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* @i: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
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*
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* Should be called under cgroup_mutex.
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*/
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#define for_each_subsys(ss, i) \
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for ((i) = 0; (i) < CGROUP_SUBSYS_COUNT; (i)++) \
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if (({ lockdep_assert_held(&cgroup_mutex); \
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!((ss) = cgroup_subsys[i]); })) { } \
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else
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/**
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* for_each_builtin_subsys - iterate all built-in cgroup subsystems
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* @ss: the iteration cursor
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* @i: the index of @ss, CGROUP_BUILTIN_SUBSYS_COUNT after reaching the end
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*
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* Bulit-in subsystems are always present and iteration itself doesn't
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* require any synchronization.
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*/
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#define for_each_builtin_subsys(ss, i) \
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for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT && \
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(((ss) = cgroup_subsys[i]) || true); (i)++)
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/* iterate each subsystem attached to a hierarchy */
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#define for_each_root_subsys(root, ss) \
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list_for_each_entry((ss), &(root)->subsys_list, sibling)
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/* iterate across the active hierarchies */
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#define for_each_active_root(root) \
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list_for_each_entry((root), &cgroup_roots, root_list)
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static inline struct cgroup *__d_cgrp(struct dentry *dentry)
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{
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return dentry->d_fsdata;
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}
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static inline struct cfent *__d_cfe(struct dentry *dentry)
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{
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return dentry->d_fsdata;
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}
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static inline struct cftype *__d_cft(struct dentry *dentry)
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{
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return __d_cfe(dentry)->type;
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}
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/**
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* cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
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* @cgrp: the cgroup to be checked for liveness
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*
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* On success, returns true; the mutex should be later unlocked. On
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* failure returns false with no lock held.
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*/
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static bool cgroup_lock_live_group(struct cgroup *cgrp)
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{
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mutex_lock(&cgroup_mutex);
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if (cgroup_is_dead(cgrp)) {
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mutex_unlock(&cgroup_mutex);
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return false;
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}
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return true;
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}
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/* the list of cgroups eligible for automatic release. Protected by
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* release_list_lock */
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static LIST_HEAD(release_list);
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static DEFINE_RAW_SPINLOCK(release_list_lock);
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static void cgroup_release_agent(struct work_struct *work);
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static DECLARE_WORK(release_agent_work, cgroup_release_agent);
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static void check_for_release(struct cgroup *cgrp);
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/*
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* A cgroup can be associated with multiple css_sets as different tasks may
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* belong to different cgroups on different hierarchies. In the other
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* direction, a css_set is naturally associated with multiple cgroups.
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* This M:N relationship is represented by the following link structure
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* which exists for each association and allows traversing the associations
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* from both sides.
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*/
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struct cgrp_cset_link {
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/* the cgroup and css_set this link associates */
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struct cgroup *cgrp;
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struct css_set *cset;
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/* list of cgrp_cset_links anchored at cgrp->cset_links */
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struct list_head cset_link;
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/* list of cgrp_cset_links anchored at css_set->cgrp_links */
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struct list_head cgrp_link;
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};
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/* The default css_set - used by init and its children prior to any
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* hierarchies being mounted. It contains a pointer to the root state
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* for each subsystem. Also used to anchor the list of css_sets. Not
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* reference-counted, to improve performance when child cgroups
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* haven't been created.
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*/
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static struct css_set init_css_set;
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static struct cgrp_cset_link init_cgrp_cset_link;
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static int cgroup_init_idr(struct cgroup_subsys *ss,
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struct cgroup_subsys_state *css);
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/* css_set_lock protects the list of css_set objects, and the
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* chain of tasks off each css_set. Nests outside task->alloc_lock
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* due to cgroup_iter_start() */
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static DEFINE_RWLOCK(css_set_lock);
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static int css_set_count;
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/*
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* hash table for cgroup groups. This improves the performance to find
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* an existing css_set. This hash doesn't (currently) take into
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* account cgroups in empty hierarchies.
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*/
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#define CSS_SET_HASH_BITS 7
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static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
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static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
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{
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unsigned long key = 0UL;
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struct cgroup_subsys *ss;
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int i;
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for_each_subsys(ss, i)
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key += (unsigned long)css[i];
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key = (key >> 16) ^ key;
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return key;
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}
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/* We don't maintain the lists running through each css_set to its
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* task until after the first call to cgroup_iter_start(). This
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* reduces the fork()/exit() overhead for people who have cgroups
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* compiled into their kernel but not actually in use */
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static int use_task_css_set_links __read_mostly;
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static void __put_css_set(struct css_set *cset, int taskexit)
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{
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struct cgrp_cset_link *link, *tmp_link;
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/*
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* Ensure that the refcount doesn't hit zero while any readers
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* can see it. Similar to atomic_dec_and_lock(), but for an
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* rwlock
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*/
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if (atomic_add_unless(&cset->refcount, -1, 1))
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return;
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write_lock(&css_set_lock);
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if (!atomic_dec_and_test(&cset->refcount)) {
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write_unlock(&css_set_lock);
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return;
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}
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/* This css_set is dead. unlink it and release cgroup refcounts */
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hash_del(&cset->hlist);
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css_set_count--;
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list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
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struct cgroup *cgrp = link->cgrp;
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list_del(&link->cset_link);
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list_del(&link->cgrp_link);
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/* @cgrp can't go away while we're holding css_set_lock */
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if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) {
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if (taskexit)
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set_bit(CGRP_RELEASABLE, &cgrp->flags);
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check_for_release(cgrp);
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}
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kfree(link);
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}
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write_unlock(&css_set_lock);
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kfree_rcu(cset, rcu_head);
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}
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/*
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* refcounted get/put for css_set objects
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*/
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static inline void get_css_set(struct css_set *cset)
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{
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atomic_inc(&cset->refcount);
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}
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static inline void put_css_set(struct css_set *cset)
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{
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__put_css_set(cset, 0);
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}
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static inline void put_css_set_taskexit(struct css_set *cset)
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{
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__put_css_set(cset, 1);
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}
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|
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/**
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* compare_css_sets - helper function for find_existing_css_set().
|
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* @cset: candidate css_set being tested
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* @old_cset: existing css_set for a task
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* @new_cgrp: cgroup that's being entered by the task
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* @template: desired set of css pointers in css_set (pre-calculated)
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*
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* Returns true if "cg" matches "old_cg" except for the hierarchy
|
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* which "new_cgrp" belongs to, for which it should match "new_cgrp".
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*/
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static bool compare_css_sets(struct css_set *cset,
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struct css_set *old_cset,
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struct cgroup *new_cgrp,
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struct cgroup_subsys_state *template[])
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{
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struct list_head *l1, *l2;
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if (memcmp(template, cset->subsys, sizeof(cset->subsys))) {
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/* Not all subsystems matched */
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return false;
|
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}
|
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|
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/*
|
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* Compare cgroup pointers in order to distinguish between
|
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* different cgroups in heirarchies with no subsystems. We
|
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* could get by with just this check alone (and skip the
|
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* memcmp above) but on most setups the memcmp check will
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* avoid the need for this more expensive check on almost all
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* candidates.
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*/
|
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l1 = &cset->cgrp_links;
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l2 = &old_cset->cgrp_links;
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while (1) {
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struct cgrp_cset_link *link1, *link2;
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struct cgroup *cgrp1, *cgrp2;
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l1 = l1->next;
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l2 = l2->next;
|
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/* See if we reached the end - both lists are equal length. */
|
|
if (l1 == &cset->cgrp_links) {
|
|
BUG_ON(l2 != &old_cset->cgrp_links);
|
|
break;
|
|
} else {
|
|
BUG_ON(l2 == &old_cset->cgrp_links);
|
|
}
|
|
/* Locate the cgroups associated with these links. */
|
|
link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
|
|
link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
|
|
cgrp1 = link1->cgrp;
|
|
cgrp2 = link2->cgrp;
|
|
/* Hierarchies should be linked in the same order. */
|
|
BUG_ON(cgrp1->root != cgrp2->root);
|
|
|
|
/*
|
|
* If this hierarchy is the hierarchy of the cgroup
|
|
* that's changing, then we need to check that this
|
|
* css_set points to the new cgroup; if it's any other
|
|
* hierarchy, then this css_set should point to the
|
|
* same cgroup as the old css_set.
|
|
*/
|
|
if (cgrp1->root == new_cgrp->root) {
|
|
if (cgrp1 != new_cgrp)
|
|
return false;
|
|
} else {
|
|
if (cgrp1 != cgrp2)
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* find_existing_css_set - init css array and find the matching css_set
|
|
* @old_cset: the css_set that we're using before the cgroup transition
|
|
* @cgrp: the cgroup that we're moving into
|
|
* @template: out param for the new set of csses, should be clear on entry
|
|
*/
|
|
static struct css_set *find_existing_css_set(struct css_set *old_cset,
|
|
struct cgroup *cgrp,
|
|
struct cgroup_subsys_state *template[])
|
|
{
|
|
struct cgroupfs_root *root = cgrp->root;
|
|
struct cgroup_subsys *ss;
|
|
struct css_set *cset;
|
|
unsigned long key;
|
|
int i;
|
|
|
|
/*
|
|
* Build the set of subsystem state objects that we want to see in the
|
|
* new css_set. while subsystems can change globally, the entries here
|
|
* won't change, so no need for locking.
|
|
*/
|
|
for_each_subsys(ss, i) {
|
|
if (root->subsys_mask & (1UL << i)) {
|
|
/* Subsystem is in this hierarchy. So we want
|
|
* the subsystem state from the new
|
|
* cgroup */
|
|
template[i] = cgrp->subsys[i];
|
|
} else {
|
|
/* Subsystem is not in this hierarchy, so we
|
|
* don't want to change the subsystem state */
|
|
template[i] = old_cset->subsys[i];
|
|
}
|
|
}
|
|
|
|
key = css_set_hash(template);
|
|
hash_for_each_possible(css_set_table, cset, hlist, key) {
|
|
if (!compare_css_sets(cset, old_cset, cgrp, template))
|
|
continue;
|
|
|
|
/* This css_set matches what we need */
|
|
return cset;
|
|
}
|
|
|
|
/* No existing cgroup group matched */
|
|
return NULL;
|
|
}
|
|
|
|
static void free_cgrp_cset_links(struct list_head *links_to_free)
|
|
{
|
|
struct cgrp_cset_link *link, *tmp_link;
|
|
|
|
list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
|
|
list_del(&link->cset_link);
|
|
kfree(link);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* allocate_cgrp_cset_links - allocate cgrp_cset_links
|
|
* @count: the number of links to allocate
|
|
* @tmp_links: list_head the allocated links are put on
|
|
*
|
|
* Allocate @count cgrp_cset_link structures and chain them on @tmp_links
|
|
* through ->cset_link. Returns 0 on success or -errno.
|
|
*/
|
|
static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
int i;
|
|
|
|
INIT_LIST_HEAD(tmp_links);
|
|
|
|
for (i = 0; i < count; i++) {
|
|
link = kzalloc(sizeof(*link), GFP_KERNEL);
|
|
if (!link) {
|
|
free_cgrp_cset_links(tmp_links);
|
|
return -ENOMEM;
|
|
}
|
|
list_add(&link->cset_link, tmp_links);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* link_css_set - a helper function to link a css_set to a cgroup
|
|
* @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
|
|
* @cset: the css_set to be linked
|
|
* @cgrp: the destination cgroup
|
|
*/
|
|
static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
|
|
struct cgroup *cgrp)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
|
|
BUG_ON(list_empty(tmp_links));
|
|
link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
|
|
link->cset = cset;
|
|
link->cgrp = cgrp;
|
|
list_move(&link->cset_link, &cgrp->cset_links);
|
|
/*
|
|
* Always add links to the tail of the list so that the list
|
|
* is sorted by order of hierarchy creation
|
|
*/
|
|
list_add_tail(&link->cgrp_link, &cset->cgrp_links);
|
|
}
|
|
|
|
/**
|
|
* find_css_set - return a new css_set with one cgroup updated
|
|
* @old_cset: the baseline css_set
|
|
* @cgrp: the cgroup to be updated
|
|
*
|
|
* Return a new css_set that's equivalent to @old_cset, but with @cgrp
|
|
* substituted into the appropriate hierarchy.
|
|
*/
|
|
static struct css_set *find_css_set(struct css_set *old_cset,
|
|
struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
|
|
struct css_set *cset;
|
|
struct list_head tmp_links;
|
|
struct cgrp_cset_link *link;
|
|
unsigned long key;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/* First see if we already have a cgroup group that matches
|
|
* the desired set */
|
|
read_lock(&css_set_lock);
|
|
cset = find_existing_css_set(old_cset, cgrp, template);
|
|
if (cset)
|
|
get_css_set(cset);
|
|
read_unlock(&css_set_lock);
|
|
|
|
if (cset)
|
|
return cset;
|
|
|
|
cset = kzalloc(sizeof(*cset), GFP_KERNEL);
|
|
if (!cset)
|
|
return NULL;
|
|
|
|
/* Allocate all the cgrp_cset_link objects that we'll need */
|
|
if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
|
|
kfree(cset);
|
|
return NULL;
|
|
}
|
|
|
|
atomic_set(&cset->refcount, 1);
|
|
INIT_LIST_HEAD(&cset->cgrp_links);
|
|
INIT_LIST_HEAD(&cset->tasks);
|
|
INIT_HLIST_NODE(&cset->hlist);
|
|
|
|
/* Copy the set of subsystem state objects generated in
|
|
* find_existing_css_set() */
|
|
memcpy(cset->subsys, template, sizeof(cset->subsys));
|
|
|
|
write_lock(&css_set_lock);
|
|
/* Add reference counts and links from the new css_set. */
|
|
list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
|
|
if (c->root == cgrp->root)
|
|
c = cgrp;
|
|
link_css_set(&tmp_links, cset, c);
|
|
}
|
|
|
|
BUG_ON(!list_empty(&tmp_links));
|
|
|
|
css_set_count++;
|
|
|
|
/* Add this cgroup group to the hash table */
|
|
key = css_set_hash(cset->subsys);
|
|
hash_add(css_set_table, &cset->hlist, key);
|
|
|
|
write_unlock(&css_set_lock);
|
|
|
|
return cset;
|
|
}
|
|
|
|
/*
|
|
* Return the cgroup for "task" from the given hierarchy. Must be
|
|
* called with cgroup_mutex held.
|
|
*/
|
|
static struct cgroup *task_cgroup_from_root(struct task_struct *task,
|
|
struct cgroupfs_root *root)
|
|
{
|
|
struct css_set *cset;
|
|
struct cgroup *res = NULL;
|
|
|
|
BUG_ON(!mutex_is_locked(&cgroup_mutex));
|
|
read_lock(&css_set_lock);
|
|
/*
|
|
* No need to lock the task - since we hold cgroup_mutex the
|
|
* task can't change groups, so the only thing that can happen
|
|
* is that it exits and its css is set back to init_css_set.
|
|
*/
|
|
cset = task_css_set(task);
|
|
if (cset == &init_css_set) {
|
|
res = &root->top_cgroup;
|
|
} else {
|
|
struct cgrp_cset_link *link;
|
|
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
|
|
if (c->root == root) {
|
|
res = c;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
read_unlock(&css_set_lock);
|
|
BUG_ON(!res);
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* There is one global cgroup mutex. We also require taking
|
|
* task_lock() when dereferencing a task's cgroup subsys pointers.
|
|
* See "The task_lock() exception", at the end of this comment.
|
|
*
|
|
* A task must hold cgroup_mutex to modify cgroups.
|
|
*
|
|
* Any task can increment and decrement the count field without lock.
|
|
* So in general, code holding cgroup_mutex can't rely on the count
|
|
* field not changing. However, if the count goes to zero, then only
|
|
* cgroup_attach_task() can increment it again. Because a count of zero
|
|
* means that no tasks are currently attached, therefore there is no
|
|
* way a task attached to that cgroup can fork (the other way to
|
|
* increment the count). So code holding cgroup_mutex can safely
|
|
* assume that if the count is zero, it will stay zero. Similarly, if
|
|
* a task holds cgroup_mutex on a cgroup with zero count, it
|
|
* knows that the cgroup won't be removed, as cgroup_rmdir()
|
|
* needs that mutex.
|
|
*
|
|
* The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
|
|
* (usually) take cgroup_mutex. These are the two most performance
|
|
* critical pieces of code here. The exception occurs on cgroup_exit(),
|
|
* when a task in a notify_on_release cgroup exits. Then cgroup_mutex
|
|
* is taken, and if the cgroup count is zero, a usermode call made
|
|
* to the release agent with the name of the cgroup (path relative to
|
|
* the root of cgroup file system) as the argument.
|
|
*
|
|
* A cgroup can only be deleted if both its 'count' of using tasks
|
|
* is zero, and its list of 'children' cgroups is empty. Since all
|
|
* tasks in the system use _some_ cgroup, and since there is always at
|
|
* least one task in the system (init, pid == 1), therefore, top_cgroup
|
|
* always has either children cgroups and/or using tasks. So we don't
|
|
* need a special hack to ensure that top_cgroup cannot be deleted.
|
|
*
|
|
* The task_lock() exception
|
|
*
|
|
* The need for this exception arises from the action of
|
|
* cgroup_attach_task(), which overwrites one task's cgroup pointer with
|
|
* another. It does so using cgroup_mutex, however there are
|
|
* several performance critical places that need to reference
|
|
* task->cgroup without the expense of grabbing a system global
|
|
* mutex. Therefore except as noted below, when dereferencing or, as
|
|
* in cgroup_attach_task(), modifying a task's cgroup pointer we use
|
|
* task_lock(), which acts on a spinlock (task->alloc_lock) already in
|
|
* the task_struct routinely used for such matters.
|
|
*
|
|
* P.S. One more locking exception. RCU is used to guard the
|
|
* update of a tasks cgroup pointer by cgroup_attach_task()
|
|
*/
|
|
|
|
/*
|
|
* A couple of forward declarations required, due to cyclic reference loop:
|
|
* cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
|
|
* cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
|
|
* -> cgroup_mkdir.
|
|
*/
|
|
|
|
static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode);
|
|
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry);
|
|
static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files,
|
|
unsigned long subsys_mask);
|
|
static const struct inode_operations cgroup_dir_inode_operations;
|
|
static const struct file_operations proc_cgroupstats_operations;
|
|
|
|
static struct backing_dev_info cgroup_backing_dev_info = {
|
|
.name = "cgroup",
|
|
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
|
|
};
|
|
|
|
static int alloc_css_id(struct cgroup_subsys *ss,
|
|
struct cgroup *parent, struct cgroup *child);
|
|
|
|
static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
|
|
{
|
|
struct inode *inode = new_inode(sb);
|
|
|
|
if (inode) {
|
|
inode->i_ino = get_next_ino();
|
|
inode->i_mode = mode;
|
|
inode->i_uid = current_fsuid();
|
|
inode->i_gid = current_fsgid();
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
|
|
inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
|
|
}
|
|
return inode;
|
|
}
|
|
|
|
static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry)
|
|
{
|
|
struct cgroup_name *name;
|
|
|
|
name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL);
|
|
if (!name)
|
|
return NULL;
|
|
strcpy(name->name, dentry->d_name.name);
|
|
return name;
|
|
}
|
|
|
|
static void cgroup_free_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
|
|
struct cgroup_subsys *ss;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
/*
|
|
* Release the subsystem state objects.
|
|
*/
|
|
for_each_root_subsys(cgrp->root, ss)
|
|
ss->css_free(cgrp);
|
|
|
|
cgrp->root->number_of_cgroups--;
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/*
|
|
* We get a ref to the parent's dentry, and put the ref when
|
|
* this cgroup is being freed, so it's guaranteed that the
|
|
* parent won't be destroyed before its children.
|
|
*/
|
|
dput(cgrp->parent->dentry);
|
|
|
|
ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);
|
|
|
|
/*
|
|
* Drop the active superblock reference that we took when we
|
|
* created the cgroup. This will free cgrp->root, if we are
|
|
* holding the last reference to @sb.
|
|
*/
|
|
deactivate_super(cgrp->root->sb);
|
|
|
|
/*
|
|
* if we're getting rid of the cgroup, refcount should ensure
|
|
* that there are no pidlists left.
|
|
*/
|
|
BUG_ON(!list_empty(&cgrp->pidlists));
|
|
|
|
simple_xattrs_free(&cgrp->xattrs);
|
|
|
|
kfree(rcu_dereference_raw(cgrp->name));
|
|
kfree(cgrp);
|
|
}
|
|
|
|
static void cgroup_free_rcu(struct rcu_head *head)
|
|
{
|
|
struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head);
|
|
|
|
INIT_WORK(&cgrp->destroy_work, cgroup_free_fn);
|
|
schedule_work(&cgrp->destroy_work);
|
|
}
|
|
|
|
static void cgroup_diput(struct dentry *dentry, struct inode *inode)
|
|
{
|
|
/* is dentry a directory ? if so, kfree() associated cgroup */
|
|
if (S_ISDIR(inode->i_mode)) {
|
|
struct cgroup *cgrp = dentry->d_fsdata;
|
|
|
|
BUG_ON(!(cgroup_is_dead(cgrp)));
|
|
call_rcu(&cgrp->rcu_head, cgroup_free_rcu);
|
|
} else {
|
|
struct cfent *cfe = __d_cfe(dentry);
|
|
struct cgroup *cgrp = dentry->d_parent->d_fsdata;
|
|
|
|
WARN_ONCE(!list_empty(&cfe->node) &&
|
|
cgrp != &cgrp->root->top_cgroup,
|
|
"cfe still linked for %s\n", cfe->type->name);
|
|
simple_xattrs_free(&cfe->xattrs);
|
|
kfree(cfe);
|
|
}
|
|
iput(inode);
|
|
}
|
|
|
|
static int cgroup_delete(const struct dentry *d)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static void remove_dir(struct dentry *d)
|
|
{
|
|
struct dentry *parent = dget(d->d_parent);
|
|
|
|
d_delete(d);
|
|
simple_rmdir(parent->d_inode, d);
|
|
dput(parent);
|
|
}
|
|
|
|
static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
|
|
{
|
|
struct cfent *cfe;
|
|
|
|
lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/*
|
|
* If we're doing cleanup due to failure of cgroup_create(),
|
|
* the corresponding @cfe may not exist.
|
|
*/
|
|
list_for_each_entry(cfe, &cgrp->files, node) {
|
|
struct dentry *d = cfe->dentry;
|
|
|
|
if (cft && cfe->type != cft)
|
|
continue;
|
|
|
|
dget(d);
|
|
d_delete(d);
|
|
simple_unlink(cgrp->dentry->d_inode, d);
|
|
list_del_init(&cfe->node);
|
|
dput(d);
|
|
|
|
break;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* cgroup_clear_directory - selective removal of base and subsystem files
|
|
* @dir: directory containing the files
|
|
* @base_files: true if the base files should be removed
|
|
* @subsys_mask: mask of the subsystem ids whose files should be removed
|
|
*/
|
|
static void cgroup_clear_directory(struct dentry *dir, bool base_files,
|
|
unsigned long subsys_mask)
|
|
{
|
|
struct cgroup *cgrp = __d_cgrp(dir);
|
|
struct cgroup_subsys *ss;
|
|
|
|
for_each_root_subsys(cgrp->root, ss) {
|
|
struct cftype_set *set;
|
|
if (!test_bit(ss->subsys_id, &subsys_mask))
|
|
continue;
|
|
list_for_each_entry(set, &ss->cftsets, node)
|
|
cgroup_addrm_files(cgrp, NULL, set->cfts, false);
|
|
}
|
|
if (base_files) {
|
|
while (!list_empty(&cgrp->files))
|
|
cgroup_rm_file(cgrp, NULL);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* NOTE : the dentry must have been dget()'ed
|
|
*/
|
|
static void cgroup_d_remove_dir(struct dentry *dentry)
|
|
{
|
|
struct dentry *parent;
|
|
struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
|
|
|
|
cgroup_clear_directory(dentry, true, root->subsys_mask);
|
|
|
|
parent = dentry->d_parent;
|
|
spin_lock(&parent->d_lock);
|
|
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
|
|
list_del_init(&dentry->d_u.d_child);
|
|
spin_unlock(&dentry->d_lock);
|
|
spin_unlock(&parent->d_lock);
|
|
remove_dir(dentry);
|
|
}
|
|
|
|
/*
|
|
* Call with cgroup_mutex held. Drops reference counts on modules, including
|
|
* any duplicate ones that parse_cgroupfs_options took. If this function
|
|
* returns an error, no reference counts are touched.
|
|
*/
|
|
static int rebind_subsystems(struct cgroupfs_root *root,
|
|
unsigned long added_mask, unsigned removed_mask)
|
|
{
|
|
struct cgroup *cgrp = &root->top_cgroup;
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
BUG_ON(!mutex_is_locked(&cgroup_mutex));
|
|
BUG_ON(!mutex_is_locked(&cgroup_root_mutex));
|
|
|
|
/* Check that any added subsystems are currently free */
|
|
for_each_subsys(ss, i) {
|
|
unsigned long bit = 1UL << i;
|
|
|
|
if (!(bit & added_mask))
|
|
continue;
|
|
|
|
if (ss->root != &cgroup_dummy_root) {
|
|
/* Subsystem isn't free */
|
|
return -EBUSY;
|
|
}
|
|
}
|
|
|
|
/* Currently we don't handle adding/removing subsystems when
|
|
* any child cgroups exist. This is theoretically supportable
|
|
* but involves complex error handling, so it's being left until
|
|
* later */
|
|
if (root->number_of_cgroups > 1)
|
|
return -EBUSY;
|
|
|
|
/* Process each subsystem */
|
|
for_each_subsys(ss, i) {
|
|
unsigned long bit = 1UL << i;
|
|
|
|
if (bit & added_mask) {
|
|
/* We're binding this subsystem to this hierarchy */
|
|
BUG_ON(cgrp->subsys[i]);
|
|
BUG_ON(!cgroup_dummy_top->subsys[i]);
|
|
BUG_ON(cgroup_dummy_top->subsys[i]->cgroup != cgroup_dummy_top);
|
|
|
|
cgrp->subsys[i] = cgroup_dummy_top->subsys[i];
|
|
cgrp->subsys[i]->cgroup = cgrp;
|
|
list_move(&ss->sibling, &root->subsys_list);
|
|
ss->root = root;
|
|
if (ss->bind)
|
|
ss->bind(cgrp);
|
|
|
|
/* refcount was already taken, and we're keeping it */
|
|
root->subsys_mask |= bit;
|
|
} else if (bit & removed_mask) {
|
|
/* We're removing this subsystem */
|
|
BUG_ON(cgrp->subsys[i] != cgroup_dummy_top->subsys[i]);
|
|
BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
|
|
|
|
if (ss->bind)
|
|
ss->bind(cgroup_dummy_top);
|
|
cgroup_dummy_top->subsys[i]->cgroup = cgroup_dummy_top;
|
|
cgrp->subsys[i] = NULL;
|
|
cgroup_subsys[i]->root = &cgroup_dummy_root;
|
|
list_move(&ss->sibling, &cgroup_dummy_root.subsys_list);
|
|
|
|
/* subsystem is now free - drop reference on module */
|
|
module_put(ss->module);
|
|
root->subsys_mask &= ~bit;
|
|
} else if (bit & root->subsys_mask) {
|
|
/* Subsystem state should already exist */
|
|
BUG_ON(!cgrp->subsys[i]);
|
|
/*
|
|
* a refcount was taken, but we already had one, so
|
|
* drop the extra reference.
|
|
*/
|
|
module_put(ss->module);
|
|
#ifdef CONFIG_MODULE_UNLOAD
|
|
BUG_ON(ss->module && !module_refcount(ss->module));
|
|
#endif
|
|
} else {
|
|
/* Subsystem state shouldn't exist */
|
|
BUG_ON(cgrp->subsys[i]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Mark @root has finished binding subsystems. @root->subsys_mask
|
|
* now matches the bound subsystems.
|
|
*/
|
|
root->flags |= CGRP_ROOT_SUBSYS_BOUND;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry)
|
|
{
|
|
struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
|
|
struct cgroup_subsys *ss;
|
|
|
|
mutex_lock(&cgroup_root_mutex);
|
|
for_each_root_subsys(root, ss)
|
|
seq_printf(seq, ",%s", ss->name);
|
|
if (root->flags & CGRP_ROOT_SANE_BEHAVIOR)
|
|
seq_puts(seq, ",sane_behavior");
|
|
if (root->flags & CGRP_ROOT_NOPREFIX)
|
|
seq_puts(seq, ",noprefix");
|
|
if (root->flags & CGRP_ROOT_XATTR)
|
|
seq_puts(seq, ",xattr");
|
|
if (strlen(root->release_agent_path))
|
|
seq_printf(seq, ",release_agent=%s", root->release_agent_path);
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags))
|
|
seq_puts(seq, ",clone_children");
|
|
if (strlen(root->name))
|
|
seq_printf(seq, ",name=%s", root->name);
|
|
mutex_unlock(&cgroup_root_mutex);
|
|
return 0;
|
|
}
|
|
|
|
struct cgroup_sb_opts {
|
|
unsigned long subsys_mask;
|
|
unsigned long flags;
|
|
char *release_agent;
|
|
bool cpuset_clone_children;
|
|
char *name;
|
|
/* User explicitly requested empty subsystem */
|
|
bool none;
|
|
|
|
struct cgroupfs_root *new_root;
|
|
|
|
};
|
|
|
|
/*
|
|
* Convert a hierarchy specifier into a bitmask of subsystems and
|
|
* flags. Call with cgroup_mutex held to protect the cgroup_subsys[]
|
|
* array. This function takes refcounts on subsystems to be used, unless it
|
|
* returns error, in which case no refcounts are taken.
|
|
*/
|
|
static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
|
|
{
|
|
char *token, *o = data;
|
|
bool all_ss = false, one_ss = false;
|
|
unsigned long mask = (unsigned long)-1;
|
|
bool module_pin_failed = false;
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
BUG_ON(!mutex_is_locked(&cgroup_mutex));
|
|
|
|
#ifdef CONFIG_CPUSETS
|
|
mask = ~(1UL << cpuset_subsys_id);
|
|
#endif
|
|
|
|
memset(opts, 0, sizeof(*opts));
|
|
|
|
while ((token = strsep(&o, ",")) != NULL) {
|
|
if (!*token)
|
|
return -EINVAL;
|
|
if (!strcmp(token, "none")) {
|
|
/* Explicitly have no subsystems */
|
|
opts->none = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "all")) {
|
|
/* Mutually exclusive option 'all' + subsystem name */
|
|
if (one_ss)
|
|
return -EINVAL;
|
|
all_ss = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "__DEVEL__sane_behavior")) {
|
|
opts->flags |= CGRP_ROOT_SANE_BEHAVIOR;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "noprefix")) {
|
|
opts->flags |= CGRP_ROOT_NOPREFIX;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "clone_children")) {
|
|
opts->cpuset_clone_children = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "xattr")) {
|
|
opts->flags |= CGRP_ROOT_XATTR;
|
|
continue;
|
|
}
|
|
if (!strncmp(token, "release_agent=", 14)) {
|
|
/* Specifying two release agents is forbidden */
|
|
if (opts->release_agent)
|
|
return -EINVAL;
|
|
opts->release_agent =
|
|
kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
|
|
if (!opts->release_agent)
|
|
return -ENOMEM;
|
|
continue;
|
|
}
|
|
if (!strncmp(token, "name=", 5)) {
|
|
const char *name = token + 5;
|
|
/* Can't specify an empty name */
|
|
if (!strlen(name))
|
|
return -EINVAL;
|
|
/* Must match [\w.-]+ */
|
|
for (i = 0; i < strlen(name); i++) {
|
|
char c = name[i];
|
|
if (isalnum(c))
|
|
continue;
|
|
if ((c == '.') || (c == '-') || (c == '_'))
|
|
continue;
|
|
return -EINVAL;
|
|
}
|
|
/* Specifying two names is forbidden */
|
|
if (opts->name)
|
|
return -EINVAL;
|
|
opts->name = kstrndup(name,
|
|
MAX_CGROUP_ROOT_NAMELEN - 1,
|
|
GFP_KERNEL);
|
|
if (!opts->name)
|
|
return -ENOMEM;
|
|
|
|
continue;
|
|
}
|
|
|
|
for_each_subsys(ss, i) {
|
|
if (strcmp(token, ss->name))
|
|
continue;
|
|
if (ss->disabled)
|
|
continue;
|
|
|
|
/* Mutually exclusive option 'all' + subsystem name */
|
|
if (all_ss)
|
|
return -EINVAL;
|
|
set_bit(i, &opts->subsys_mask);
|
|
one_ss = true;
|
|
|
|
break;
|
|
}
|
|
if (i == CGROUP_SUBSYS_COUNT)
|
|
return -ENOENT;
|
|
}
|
|
|
|
/*
|
|
* If the 'all' option was specified select all the subsystems,
|
|
* otherwise if 'none', 'name=' and a subsystem name options
|
|
* were not specified, let's default to 'all'
|
|
*/
|
|
if (all_ss || (!one_ss && !opts->none && !opts->name))
|
|
for_each_subsys(ss, i)
|
|
if (!ss->disabled)
|
|
set_bit(i, &opts->subsys_mask);
|
|
|
|
/* Consistency checks */
|
|
|
|
if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
|
pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
|
|
|
|
if (opts->flags & CGRP_ROOT_NOPREFIX) {
|
|
pr_err("cgroup: sane_behavior: noprefix is not allowed\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (opts->cpuset_clone_children) {
|
|
pr_err("cgroup: sane_behavior: clone_children is not allowed\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Option noprefix was introduced just for backward compatibility
|
|
* with the old cpuset, so we allow noprefix only if mounting just
|
|
* the cpuset subsystem.
|
|
*/
|
|
if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
|
|
return -EINVAL;
|
|
|
|
|
|
/* Can't specify "none" and some subsystems */
|
|
if (opts->subsys_mask && opts->none)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* We either have to specify by name or by subsystems. (So all
|
|
* empty hierarchies must have a name).
|
|
*/
|
|
if (!opts->subsys_mask && !opts->name)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Grab references on all the modules we'll need, so the subsystems
|
|
* don't dance around before rebind_subsystems attaches them. This may
|
|
* take duplicate reference counts on a subsystem that's already used,
|
|
* but rebind_subsystems handles this case.
|
|
*/
|
|
for_each_subsys(ss, i) {
|
|
if (!(opts->subsys_mask & (1UL << i)))
|
|
continue;
|
|
if (!try_module_get(cgroup_subsys[i]->module)) {
|
|
module_pin_failed = true;
|
|
break;
|
|
}
|
|
}
|
|
if (module_pin_failed) {
|
|
/*
|
|
* oops, one of the modules was going away. this means that we
|
|
* raced with a module_delete call, and to the user this is
|
|
* essentially a "subsystem doesn't exist" case.
|
|
*/
|
|
for (i--; i >= 0; i--) {
|
|
/* drop refcounts only on the ones we took */
|
|
unsigned long bit = 1UL << i;
|
|
|
|
if (!(bit & opts->subsys_mask))
|
|
continue;
|
|
module_put(cgroup_subsys[i]->module);
|
|
}
|
|
return -ENOENT;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void drop_parsed_module_refcounts(unsigned long subsys_mask)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
for_each_subsys(ss, i)
|
|
if (subsys_mask & (1UL << i))
|
|
module_put(cgroup_subsys[i]->module);
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
static int cgroup_remount(struct super_block *sb, int *flags, char *data)
|
|
{
|
|
int ret = 0;
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
struct cgroup *cgrp = &root->top_cgroup;
|
|
struct cgroup_sb_opts opts;
|
|
unsigned long added_mask, removed_mask;
|
|
|
|
if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
|
pr_err("cgroup: sane_behavior: remount is not allowed\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
mutex_lock(&cgrp->dentry->d_inode->i_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
mutex_lock(&cgroup_root_mutex);
|
|
|
|
/* See what subsystems are wanted */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
|
|
pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
|
|
task_tgid_nr(current), current->comm);
|
|
|
|
added_mask = opts.subsys_mask & ~root->subsys_mask;
|
|
removed_mask = root->subsys_mask & ~opts.subsys_mask;
|
|
|
|
/* Don't allow flags or name to change at remount */
|
|
if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) ||
|
|
(opts.name && strcmp(opts.name, root->name))) {
|
|
pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n",
|
|
opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "",
|
|
root->flags & CGRP_ROOT_OPTION_MASK, root->name);
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* Clear out the files of subsystems that should be removed, do
|
|
* this before rebind_subsystems, since rebind_subsystems may
|
|
* change this hierarchy's subsys_list.
|
|
*/
|
|
cgroup_clear_directory(cgrp->dentry, false, removed_mask);
|
|
|
|
ret = rebind_subsystems(root, added_mask, removed_mask);
|
|
if (ret) {
|
|
/* rebind_subsystems failed, re-populate the removed files */
|
|
cgroup_populate_dir(cgrp, false, removed_mask);
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* re-populate subsystem files */
|
|
cgroup_populate_dir(cgrp, false, added_mask);
|
|
|
|
if (opts.release_agent)
|
|
strcpy(root->release_agent_path, opts.release_agent);
|
|
out_unlock:
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
mutex_unlock(&cgroup_root_mutex);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
|
|
if (ret)
|
|
drop_parsed_module_refcounts(opts.subsys_mask);
|
|
return ret;
|
|
}
|
|
|
|
static const struct super_operations cgroup_ops = {
|
|
.statfs = simple_statfs,
|
|
.drop_inode = generic_delete_inode,
|
|
.show_options = cgroup_show_options,
|
|
.remount_fs = cgroup_remount,
|
|
};
|
|
|
|
static void init_cgroup_housekeeping(struct cgroup *cgrp)
|
|
{
|
|
INIT_LIST_HEAD(&cgrp->sibling);
|
|
INIT_LIST_HEAD(&cgrp->children);
|
|
INIT_LIST_HEAD(&cgrp->files);
|
|
INIT_LIST_HEAD(&cgrp->cset_links);
|
|
INIT_LIST_HEAD(&cgrp->release_list);
|
|
INIT_LIST_HEAD(&cgrp->pidlists);
|
|
mutex_init(&cgrp->pidlist_mutex);
|
|
INIT_LIST_HEAD(&cgrp->event_list);
|
|
spin_lock_init(&cgrp->event_list_lock);
|
|
simple_xattrs_init(&cgrp->xattrs);
|
|
}
|
|
|
|
static void init_cgroup_root(struct cgroupfs_root *root)
|
|
{
|
|
struct cgroup *cgrp = &root->top_cgroup;
|
|
|
|
INIT_LIST_HEAD(&root->subsys_list);
|
|
INIT_LIST_HEAD(&root->root_list);
|
|
root->number_of_cgroups = 1;
|
|
cgrp->root = root;
|
|
RCU_INIT_POINTER(cgrp->name, &root_cgroup_name);
|
|
init_cgroup_housekeeping(cgrp);
|
|
}
|
|
|
|
static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end)
|
|
{
|
|
int id;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
lockdep_assert_held(&cgroup_root_mutex);
|
|
|
|
id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, start, end,
|
|
GFP_KERNEL);
|
|
if (id < 0)
|
|
return id;
|
|
|
|
root->hierarchy_id = id;
|
|
return 0;
|
|
}
|
|
|
|
static void cgroup_exit_root_id(struct cgroupfs_root *root)
|
|
{
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
lockdep_assert_held(&cgroup_root_mutex);
|
|
|
|
if (root->hierarchy_id) {
|
|
idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
|
|
root->hierarchy_id = 0;
|
|
}
|
|
}
|
|
|
|
static int cgroup_test_super(struct super_block *sb, void *data)
|
|
{
|
|
struct cgroup_sb_opts *opts = data;
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
|
|
/* If we asked for a name then it must match */
|
|
if (opts->name && strcmp(opts->name, root->name))
|
|
return 0;
|
|
|
|
/*
|
|
* If we asked for subsystems (or explicitly for no
|
|
* subsystems) then they must match
|
|
*/
|
|
if ((opts->subsys_mask || opts->none)
|
|
&& (opts->subsys_mask != root->subsys_mask))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
|
|
{
|
|
struct cgroupfs_root *root;
|
|
|
|
if (!opts->subsys_mask && !opts->none)
|
|
return NULL;
|
|
|
|
root = kzalloc(sizeof(*root), GFP_KERNEL);
|
|
if (!root)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
init_cgroup_root(root);
|
|
|
|
/*
|
|
* We need to set @root->subsys_mask now so that @root can be
|
|
* matched by cgroup_test_super() before it finishes
|
|
* initialization; otherwise, competing mounts with the same
|
|
* options may try to bind the same subsystems instead of waiting
|
|
* for the first one leading to unexpected mount errors.
|
|
* SUBSYS_BOUND will be set once actual binding is complete.
|
|
*/
|
|
root->subsys_mask = opts->subsys_mask;
|
|
root->flags = opts->flags;
|
|
ida_init(&root->cgroup_ida);
|
|
if (opts->release_agent)
|
|
strcpy(root->release_agent_path, opts->release_agent);
|
|
if (opts->name)
|
|
strcpy(root->name, opts->name);
|
|
if (opts->cpuset_clone_children)
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags);
|
|
return root;
|
|
}
|
|
|
|
static void cgroup_free_root(struct cgroupfs_root *root)
|
|
{
|
|
if (root) {
|
|
/* hierarhcy ID shoulid already have been released */
|
|
WARN_ON_ONCE(root->hierarchy_id);
|
|
|
|
ida_destroy(&root->cgroup_ida);
|
|
kfree(root);
|
|
}
|
|
}
|
|
|
|
static int cgroup_set_super(struct super_block *sb, void *data)
|
|
{
|
|
int ret;
|
|
struct cgroup_sb_opts *opts = data;
|
|
|
|
/* If we don't have a new root, we can't set up a new sb */
|
|
if (!opts->new_root)
|
|
return -EINVAL;
|
|
|
|
BUG_ON(!opts->subsys_mask && !opts->none);
|
|
|
|
ret = set_anon_super(sb, NULL);
|
|
if (ret)
|
|
return ret;
|
|
|
|
sb->s_fs_info = opts->new_root;
|
|
opts->new_root->sb = sb;
|
|
|
|
sb->s_blocksize = PAGE_CACHE_SIZE;
|
|
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
|
|
sb->s_magic = CGROUP_SUPER_MAGIC;
|
|
sb->s_op = &cgroup_ops;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_get_rootdir(struct super_block *sb)
|
|
{
|
|
static const struct dentry_operations cgroup_dops = {
|
|
.d_iput = cgroup_diput,
|
|
.d_delete = cgroup_delete,
|
|
};
|
|
|
|
struct inode *inode =
|
|
cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb);
|
|
|
|
if (!inode)
|
|
return -ENOMEM;
|
|
|
|
inode->i_fop = &simple_dir_operations;
|
|
inode->i_op = &cgroup_dir_inode_operations;
|
|
/* directories start off with i_nlink == 2 (for "." entry) */
|
|
inc_nlink(inode);
|
|
sb->s_root = d_make_root(inode);
|
|
if (!sb->s_root)
|
|
return -ENOMEM;
|
|
/* for everything else we want ->d_op set */
|
|
sb->s_d_op = &cgroup_dops;
|
|
return 0;
|
|
}
|
|
|
|
static struct dentry *cgroup_mount(struct file_system_type *fs_type,
|
|
int flags, const char *unused_dev_name,
|
|
void *data)
|
|
{
|
|
struct cgroup_sb_opts opts;
|
|
struct cgroupfs_root *root;
|
|
int ret = 0;
|
|
struct super_block *sb;
|
|
struct cgroupfs_root *new_root;
|
|
struct inode *inode;
|
|
|
|
/* First find the desired set of subsystems */
|
|
mutex_lock(&cgroup_mutex);
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
mutex_unlock(&cgroup_mutex);
|
|
if (ret)
|
|
goto out_err;
|
|
|
|
/*
|
|
* Allocate a new cgroup root. We may not need it if we're
|
|
* reusing an existing hierarchy.
|
|
*/
|
|
new_root = cgroup_root_from_opts(&opts);
|
|
if (IS_ERR(new_root)) {
|
|
ret = PTR_ERR(new_root);
|
|
goto drop_modules;
|
|
}
|
|
opts.new_root = new_root;
|
|
|
|
/* Locate an existing or new sb for this hierarchy */
|
|
sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts);
|
|
if (IS_ERR(sb)) {
|
|
ret = PTR_ERR(sb);
|
|
cgroup_free_root(opts.new_root);
|
|
goto drop_modules;
|
|
}
|
|
|
|
root = sb->s_fs_info;
|
|
BUG_ON(!root);
|
|
if (root == opts.new_root) {
|
|
/* We used the new root structure, so this is a new hierarchy */
|
|
struct list_head tmp_links;
|
|
struct cgroup *root_cgrp = &root->top_cgroup;
|
|
struct cgroupfs_root *existing_root;
|
|
const struct cred *cred;
|
|
int i;
|
|
struct css_set *cset;
|
|
|
|
BUG_ON(sb->s_root != NULL);
|
|
|
|
ret = cgroup_get_rootdir(sb);
|
|
if (ret)
|
|
goto drop_new_super;
|
|
inode = sb->s_root->d_inode;
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
mutex_lock(&cgroup_root_mutex);
|
|
|
|
/* Check for name clashes with existing mounts */
|
|
ret = -EBUSY;
|
|
if (strlen(root->name))
|
|
for_each_active_root(existing_root)
|
|
if (!strcmp(existing_root->name, root->name))
|
|
goto unlock_drop;
|
|
|
|
/*
|
|
* We're accessing css_set_count without locking
|
|
* css_set_lock here, but that's OK - it can only be
|
|
* increased by someone holding cgroup_lock, and
|
|
* that's us. The worst that can happen is that we
|
|
* have some link structures left over
|
|
*/
|
|
ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
|
|
if (ret)
|
|
goto unlock_drop;
|
|
|
|
/* ID 0 is reserved for dummy root, 1 for unified hierarchy */
|
|
ret = cgroup_init_root_id(root, 2, 0);
|
|
if (ret)
|
|
goto unlock_drop;
|
|
|
|
ret = rebind_subsystems(root, root->subsys_mask, 0);
|
|
if (ret == -EBUSY) {
|
|
free_cgrp_cset_links(&tmp_links);
|
|
goto unlock_drop;
|
|
}
|
|
/*
|
|
* There must be no failure case after here, since rebinding
|
|
* takes care of subsystems' refcounts, which are explicitly
|
|
* dropped in the failure exit path.
|
|
*/
|
|
|
|
/* EBUSY should be the only error here */
|
|
BUG_ON(ret);
|
|
|
|
list_add(&root->root_list, &cgroup_roots);
|
|
cgroup_root_count++;
|
|
|
|
sb->s_root->d_fsdata = root_cgrp;
|
|
root->top_cgroup.dentry = sb->s_root;
|
|
|
|
/* Link the top cgroup in this hierarchy into all
|
|
* the css_set objects */
|
|
write_lock(&css_set_lock);
|
|
hash_for_each(css_set_table, i, cset, hlist)
|
|
link_css_set(&tmp_links, cset, root_cgrp);
|
|
write_unlock(&css_set_lock);
|
|
|
|
free_cgrp_cset_links(&tmp_links);
|
|
|
|
BUG_ON(!list_empty(&root_cgrp->children));
|
|
BUG_ON(root->number_of_cgroups != 1);
|
|
|
|
cred = override_creds(&init_cred);
|
|
cgroup_populate_dir(root_cgrp, true, root->subsys_mask);
|
|
revert_creds(cred);
|
|
mutex_unlock(&cgroup_root_mutex);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&inode->i_mutex);
|
|
} else {
|
|
/*
|
|
* We re-used an existing hierarchy - the new root (if
|
|
* any) is not needed
|
|
*/
|
|
cgroup_free_root(opts.new_root);
|
|
|
|
if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) {
|
|
if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) {
|
|
pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
|
|
ret = -EINVAL;
|
|
goto drop_new_super;
|
|
} else {
|
|
pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");
|
|
}
|
|
}
|
|
|
|
/* no subsys rebinding, so refcounts don't change */
|
|
drop_parsed_module_refcounts(opts.subsys_mask);
|
|
}
|
|
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
return dget(sb->s_root);
|
|
|
|
unlock_drop:
|
|
cgroup_exit_root_id(root);
|
|
mutex_unlock(&cgroup_root_mutex);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&inode->i_mutex);
|
|
drop_new_super:
|
|
deactivate_locked_super(sb);
|
|
drop_modules:
|
|
drop_parsed_module_refcounts(opts.subsys_mask);
|
|
out_err:
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
static void cgroup_kill_sb(struct super_block *sb) {
|
|
struct cgroupfs_root *root = sb->s_fs_info;
|
|
struct cgroup *cgrp = &root->top_cgroup;
|
|
struct cgrp_cset_link *link, *tmp_link;
|
|
int ret;
|
|
|
|
BUG_ON(!root);
|
|
|
|
BUG_ON(root->number_of_cgroups != 1);
|
|
BUG_ON(!list_empty(&cgrp->children));
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
mutex_lock(&cgroup_root_mutex);
|
|
|
|
/* Rebind all subsystems back to the default hierarchy */
|
|
if (root->flags & CGRP_ROOT_SUBSYS_BOUND) {
|
|
ret = rebind_subsystems(root, 0, root->subsys_mask);
|
|
/* Shouldn't be able to fail ... */
|
|
BUG_ON(ret);
|
|
}
|
|
|
|
/*
|
|
* Release all the links from cset_links to this hierarchy's
|
|
* root cgroup
|
|
*/
|
|
write_lock(&css_set_lock);
|
|
|
|
list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
|
|
list_del(&link->cset_link);
|
|
list_del(&link->cgrp_link);
|
|
kfree(link);
|
|
}
|
|
write_unlock(&css_set_lock);
|
|
|
|
if (!list_empty(&root->root_list)) {
|
|
list_del(&root->root_list);
|
|
cgroup_root_count--;
|
|
}
|
|
|
|
cgroup_exit_root_id(root);
|
|
|
|
mutex_unlock(&cgroup_root_mutex);
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
simple_xattrs_free(&cgrp->xattrs);
|
|
|
|
kill_litter_super(sb);
|
|
cgroup_free_root(root);
|
|
}
|
|
|
|
static struct file_system_type cgroup_fs_type = {
|
|
.name = "cgroup",
|
|
.mount = cgroup_mount,
|
|
.kill_sb = cgroup_kill_sb,
|
|
};
|
|
|
|
static struct kobject *cgroup_kobj;
|
|
|
|
/**
|
|
* cgroup_path - generate the path of a cgroup
|
|
* @cgrp: the cgroup in question
|
|
* @buf: the buffer to write the path into
|
|
* @buflen: the length of the buffer
|
|
*
|
|
* Writes path of cgroup into buf. Returns 0 on success, -errno on error.
|
|
*
|
|
* We can't generate cgroup path using dentry->d_name, as accessing
|
|
* dentry->name must be protected by irq-unsafe dentry->d_lock or parent
|
|
* inode's i_mutex, while on the other hand cgroup_path() can be called
|
|
* with some irq-safe spinlocks held.
|
|
*/
|
|
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
|
|
{
|
|
int ret = -ENAMETOOLONG;
|
|
char *start;
|
|
|
|
if (!cgrp->parent) {
|
|
if (strlcpy(buf, "/", buflen) >= buflen)
|
|
return -ENAMETOOLONG;
|
|
return 0;
|
|
}
|
|
|
|
start = buf + buflen - 1;
|
|
*start = '\0';
|
|
|
|
rcu_read_lock();
|
|
do {
|
|
const char *name = cgroup_name(cgrp);
|
|
int len;
|
|
|
|
len = strlen(name);
|
|
if ((start -= len) < buf)
|
|
goto out;
|
|
memcpy(start, name, len);
|
|
|
|
if (--start < buf)
|
|
goto out;
|
|
*start = '/';
|
|
|
|
cgrp = cgrp->parent;
|
|
} while (cgrp->parent);
|
|
ret = 0;
|
|
memmove(buf, start, buf + buflen - start);
|
|
out:
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_path);
|
|
|
|
/**
|
|
* task_cgroup_path_from_hierarchy - cgroup path of a task on a hierarchy
|
|
* @task: target task
|
|
* @hierarchy_id: the hierarchy to look up @task's cgroup from
|
|
* @buf: the buffer to write the path into
|
|
* @buflen: the length of the buffer
|
|
*
|
|
* Determine @task's cgroup on the hierarchy specified by @hierarchy_id and
|
|
* copy its path into @buf. This function grabs cgroup_mutex and shouldn't
|
|
* be used inside locks used by cgroup controller callbacks.
|
|
*/
|
|
int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id,
|
|
char *buf, size_t buflen)
|
|
{
|
|
struct cgroupfs_root *root;
|
|
struct cgroup *cgrp = NULL;
|
|
int ret = -ENOENT;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
root = idr_find(&cgroup_hierarchy_idr, hierarchy_id);
|
|
if (root) {
|
|
cgrp = task_cgroup_from_root(task, root);
|
|
ret = cgroup_path(cgrp, buf, buflen);
|
|
}
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(task_cgroup_path_from_hierarchy);
|
|
|
|
/*
|
|
* Control Group taskset
|
|
*/
|
|
struct task_and_cgroup {
|
|
struct task_struct *task;
|
|
struct cgroup *cgrp;
|
|
struct css_set *cg;
|
|
};
|
|
|
|
struct cgroup_taskset {
|
|
struct task_and_cgroup single;
|
|
struct flex_array *tc_array;
|
|
int tc_array_len;
|
|
int idx;
|
|
struct cgroup *cur_cgrp;
|
|
};
|
|
|
|
/**
|
|
* cgroup_taskset_first - reset taskset and return the first task
|
|
* @tset: taskset of interest
|
|
*
|
|
* @tset iteration is initialized and the first task is returned.
|
|
*/
|
|
struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset)
|
|
{
|
|
if (tset->tc_array) {
|
|
tset->idx = 0;
|
|
return cgroup_taskset_next(tset);
|
|
} else {
|
|
tset->cur_cgrp = tset->single.cgrp;
|
|
return tset->single.task;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_taskset_first);
|
|
|
|
/**
|
|
* cgroup_taskset_next - iterate to the next task in taskset
|
|
* @tset: taskset of interest
|
|
*
|
|
* Return the next task in @tset. Iteration must have been initialized
|
|
* with cgroup_taskset_first().
|
|
*/
|
|
struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
|
|
{
|
|
struct task_and_cgroup *tc;
|
|
|
|
if (!tset->tc_array || tset->idx >= tset->tc_array_len)
|
|
return NULL;
|
|
|
|
tc = flex_array_get(tset->tc_array, tset->idx++);
|
|
tset->cur_cgrp = tc->cgrp;
|
|
return tc->task;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_taskset_next);
|
|
|
|
/**
|
|
* cgroup_taskset_cur_cgroup - return the matching cgroup for the current task
|
|
* @tset: taskset of interest
|
|
*
|
|
* Return the cgroup for the current (last returned) task of @tset. This
|
|
* function must be preceded by either cgroup_taskset_first() or
|
|
* cgroup_taskset_next().
|
|
*/
|
|
struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset)
|
|
{
|
|
return tset->cur_cgrp;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup);
|
|
|
|
/**
|
|
* cgroup_taskset_size - return the number of tasks in taskset
|
|
* @tset: taskset of interest
|
|
*/
|
|
int cgroup_taskset_size(struct cgroup_taskset *tset)
|
|
{
|
|
return tset->tc_array ? tset->tc_array_len : 1;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_taskset_size);
|
|
|
|
|
|
/*
|
|
* cgroup_task_migrate - move a task from one cgroup to another.
|
|
*
|
|
* Must be called with cgroup_mutex and threadgroup locked.
|
|
*/
|
|
static void cgroup_task_migrate(struct cgroup *old_cgrp,
|
|
struct task_struct *tsk,
|
|
struct css_set *new_cset)
|
|
{
|
|
struct css_set *old_cset;
|
|
|
|
/*
|
|
* We are synchronized through threadgroup_lock() against PF_EXITING
|
|
* setting such that we can't race against cgroup_exit() changing the
|
|
* css_set to init_css_set and dropping the old one.
|
|
*/
|
|
WARN_ON_ONCE(tsk->flags & PF_EXITING);
|
|
old_cset = task_css_set(tsk);
|
|
|
|
task_lock(tsk);
|
|
rcu_assign_pointer(tsk->cgroups, new_cset);
|
|
task_unlock(tsk);
|
|
|
|
/* Update the css_set linked lists if we're using them */
|
|
write_lock(&css_set_lock);
|
|
if (!list_empty(&tsk->cg_list))
|
|
list_move(&tsk->cg_list, &new_cset->tasks);
|
|
write_unlock(&css_set_lock);
|
|
|
|
/*
|
|
* We just gained a reference on old_cset by taking it from the
|
|
* task. As trading it for new_cset is protected by cgroup_mutex,
|
|
* we're safe to drop it here; it will be freed under RCU.
|
|
*/
|
|
set_bit(CGRP_RELEASABLE, &old_cgrp->flags);
|
|
put_css_set(old_cset);
|
|
}
|
|
|
|
/**
|
|
* cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
|
|
* @cgrp: the cgroup to attach to
|
|
* @tsk: the task or the leader of the threadgroup to be attached
|
|
* @threadgroup: attach the whole threadgroup?
|
|
*
|
|
* Call holding cgroup_mutex and the group_rwsem of the leader. Will take
|
|
* task_lock of @tsk or each thread in the threadgroup individually in turn.
|
|
*/
|
|
static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,
|
|
bool threadgroup)
|
|
{
|
|
int retval, i, group_size;
|
|
struct cgroup_subsys *ss, *failed_ss = NULL;
|
|
struct cgroupfs_root *root = cgrp->root;
|
|
/* threadgroup list cursor and array */
|
|
struct task_struct *leader = tsk;
|
|
struct task_and_cgroup *tc;
|
|
struct flex_array *group;
|
|
struct cgroup_taskset tset = { };
|
|
|
|
/*
|
|
* step 0: in order to do expensive, possibly blocking operations for
|
|
* every thread, we cannot iterate the thread group list, since it needs
|
|
* rcu or tasklist locked. instead, build an array of all threads in the
|
|
* group - group_rwsem prevents new threads from appearing, and if
|
|
* threads exit, this will just be an over-estimate.
|
|
*/
|
|
if (threadgroup)
|
|
group_size = get_nr_threads(tsk);
|
|
else
|
|
group_size = 1;
|
|
/* flex_array supports very large thread-groups better than kmalloc. */
|
|
group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL);
|
|
if (!group)
|
|
return -ENOMEM;
|
|
/* pre-allocate to guarantee space while iterating in rcu read-side. */
|
|
retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL);
|
|
if (retval)
|
|
goto out_free_group_list;
|
|
|
|
i = 0;
|
|
/*
|
|
* Prevent freeing of tasks while we take a snapshot. Tasks that are
|
|
* already PF_EXITING could be freed from underneath us unless we
|
|
* take an rcu_read_lock.
|
|
*/
|
|
rcu_read_lock();
|
|
do {
|
|
struct task_and_cgroup ent;
|
|
|
|
/* @tsk either already exited or can't exit until the end */
|
|
if (tsk->flags & PF_EXITING)
|
|
continue;
|
|
|
|
/* as per above, nr_threads may decrease, but not increase. */
|
|
BUG_ON(i >= group_size);
|
|
ent.task = tsk;
|
|
ent.cgrp = task_cgroup_from_root(tsk, root);
|
|
/* nothing to do if this task is already in the cgroup */
|
|
if (ent.cgrp == cgrp)
|
|
continue;
|
|
/*
|
|
* saying GFP_ATOMIC has no effect here because we did prealloc
|
|
* earlier, but it's good form to communicate our expectations.
|
|
*/
|
|
retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
|
|
BUG_ON(retval != 0);
|
|
i++;
|
|
|
|
if (!threadgroup)
|
|
break;
|
|
} while_each_thread(leader, tsk);
|
|
rcu_read_unlock();
|
|
/* remember the number of threads in the array for later. */
|
|
group_size = i;
|
|
tset.tc_array = group;
|
|
tset.tc_array_len = group_size;
|
|
|
|
/* methods shouldn't be called if no task is actually migrating */
|
|
retval = 0;
|
|
if (!group_size)
|
|
goto out_free_group_list;
|
|
|
|
/*
|
|
* step 1: check that we can legitimately attach to the cgroup.
|
|
*/
|
|
for_each_root_subsys(root, ss) {
|
|
if (ss->can_attach) {
|
|
retval = ss->can_attach(cgrp, &tset);
|
|
if (retval) {
|
|
failed_ss = ss;
|
|
goto out_cancel_attach;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* step 2: make sure css_sets exist for all threads to be migrated.
|
|
* we use find_css_set, which allocates a new one if necessary.
|
|
*/
|
|
for (i = 0; i < group_size; i++) {
|
|
struct css_set *old_cset;
|
|
|
|
tc = flex_array_get(group, i);
|
|
old_cset = task_css_set(tc->task);
|
|
tc->cg = find_css_set(old_cset, cgrp);
|
|
if (!tc->cg) {
|
|
retval = -ENOMEM;
|
|
goto out_put_css_set_refs;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* step 3: now that we're guaranteed success wrt the css_sets,
|
|
* proceed to move all tasks to the new cgroup. There are no
|
|
* failure cases after here, so this is the commit point.
|
|
*/
|
|
for (i = 0; i < group_size; i++) {
|
|
tc = flex_array_get(group, i);
|
|
cgroup_task_migrate(tc->cgrp, tc->task, tc->cg);
|
|
}
|
|
/* nothing is sensitive to fork() after this point. */
|
|
|
|
/*
|
|
* step 4: do subsystem attach callbacks.
|
|
*/
|
|
for_each_root_subsys(root, ss) {
|
|
if (ss->attach)
|
|
ss->attach(cgrp, &tset);
|
|
}
|
|
|
|
/*
|
|
* step 5: success! and cleanup
|
|
*/
|
|
retval = 0;
|
|
out_put_css_set_refs:
|
|
if (retval) {
|
|
for (i = 0; i < group_size; i++) {
|
|
tc = flex_array_get(group, i);
|
|
if (!tc->cg)
|
|
break;
|
|
put_css_set(tc->cg);
|
|
}
|
|
}
|
|
out_cancel_attach:
|
|
if (retval) {
|
|
for_each_root_subsys(root, ss) {
|
|
if (ss == failed_ss)
|
|
break;
|
|
if (ss->cancel_attach)
|
|
ss->cancel_attach(cgrp, &tset);
|
|
}
|
|
}
|
|
out_free_group_list:
|
|
flex_array_free(group);
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* Find the task_struct of the task to attach by vpid and pass it along to the
|
|
* function to attach either it or all tasks in its threadgroup. Will lock
|
|
* cgroup_mutex and threadgroup; may take task_lock of task.
|
|
*/
|
|
static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
|
|
{
|
|
struct task_struct *tsk;
|
|
const struct cred *cred = current_cred(), *tcred;
|
|
int ret;
|
|
|
|
if (!cgroup_lock_live_group(cgrp))
|
|
return -ENODEV;
|
|
|
|
retry_find_task:
|
|
rcu_read_lock();
|
|
if (pid) {
|
|
tsk = find_task_by_vpid(pid);
|
|
if (!tsk) {
|
|
rcu_read_unlock();
|
|
ret= -ESRCH;
|
|
goto out_unlock_cgroup;
|
|
}
|
|
/*
|
|
* even if we're attaching all tasks in the thread group, we
|
|
* only need to check permissions on one of them.
|
|
*/
|
|
tcred = __task_cred(tsk);
|
|
if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
|
|
!uid_eq(cred->euid, tcred->uid) &&
|
|
!uid_eq(cred->euid, tcred->suid)) {
|
|
rcu_read_unlock();
|
|
ret = -EACCES;
|
|
goto out_unlock_cgroup;
|
|
}
|
|
} else
|
|
tsk = current;
|
|
|
|
if (threadgroup)
|
|
tsk = tsk->group_leader;
|
|
|
|
/*
|
|
* Workqueue threads may acquire PF_NO_SETAFFINITY and become
|
|
* trapped in a cpuset, or RT worker may be born in a cgroup
|
|
* with no rt_runtime allocated. Just say no.
|
|
*/
|
|
if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
|
|
ret = -EINVAL;
|
|
rcu_read_unlock();
|
|
goto out_unlock_cgroup;
|
|
}
|
|
|
|
get_task_struct(tsk);
|
|
rcu_read_unlock();
|
|
|
|
threadgroup_lock(tsk);
|
|
if (threadgroup) {
|
|
if (!thread_group_leader(tsk)) {
|
|
/*
|
|
* a race with de_thread from another thread's exec()
|
|
* may strip us of our leadership, if this happens,
|
|
* there is no choice but to throw this task away and
|
|
* try again; this is
|
|
* "double-double-toil-and-trouble-check locking".
|
|
*/
|
|
threadgroup_unlock(tsk);
|
|
put_task_struct(tsk);
|
|
goto retry_find_task;
|
|
}
|
|
}
|
|
|
|
ret = cgroup_attach_task(cgrp, tsk, threadgroup);
|
|
|
|
threadgroup_unlock(tsk);
|
|
|
|
put_task_struct(tsk);
|
|
out_unlock_cgroup:
|
|
mutex_unlock(&cgroup_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
|
|
* @from: attach to all cgroups of a given task
|
|
* @tsk: the task to be attached
|
|
*/
|
|
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
|
|
{
|
|
struct cgroupfs_root *root;
|
|
int retval = 0;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
for_each_active_root(root) {
|
|
struct cgroup *from_cg = task_cgroup_from_root(from, root);
|
|
|
|
retval = cgroup_attach_task(from_cg, tsk, false);
|
|
if (retval)
|
|
break;
|
|
}
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
return retval;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
|
|
|
|
static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid)
|
|
{
|
|
return attach_task_by_pid(cgrp, pid, false);
|
|
}
|
|
|
|
static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid)
|
|
{
|
|
return attach_task_by_pid(cgrp, tgid, true);
|
|
}
|
|
|
|
static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft,
|
|
const char *buffer)
|
|
{
|
|
BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
|
|
if (strlen(buffer) >= PATH_MAX)
|
|
return -EINVAL;
|
|
if (!cgroup_lock_live_group(cgrp))
|
|
return -ENODEV;
|
|
mutex_lock(&cgroup_root_mutex);
|
|
strcpy(cgrp->root->release_agent_path, buffer);
|
|
mutex_unlock(&cgroup_root_mutex);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *seq)
|
|
{
|
|
if (!cgroup_lock_live_group(cgrp))
|
|
return -ENODEV;
|
|
seq_puts(seq, cgrp->root->release_agent_path);
|
|
seq_putc(seq, '\n');
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_sane_behavior_show(struct cgroup *cgrp, struct cftype *cft,
|
|
struct seq_file *seq)
|
|
{
|
|
seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp));
|
|
return 0;
|
|
}
|
|
|
|
/* A buffer size big enough for numbers or short strings */
|
|
#define CGROUP_LOCAL_BUFFER_SIZE 64
|
|
|
|
static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,
|
|
struct file *file,
|
|
const char __user *userbuf,
|
|
size_t nbytes, loff_t *unused_ppos)
|
|
{
|
|
char buffer[CGROUP_LOCAL_BUFFER_SIZE];
|
|
int retval = 0;
|
|
char *end;
|
|
|
|
if (!nbytes)
|
|
return -EINVAL;
|
|
if (nbytes >= sizeof(buffer))
|
|
return -E2BIG;
|
|
if (copy_from_user(buffer, userbuf, nbytes))
|
|
return -EFAULT;
|
|
|
|
buffer[nbytes] = 0; /* nul-terminate */
|
|
if (cft->write_u64) {
|
|
u64 val = simple_strtoull(strstrip(buffer), &end, 0);
|
|
if (*end)
|
|
return -EINVAL;
|
|
retval = cft->write_u64(cgrp, cft, val);
|
|
} else {
|
|
s64 val = simple_strtoll(strstrip(buffer), &end, 0);
|
|
if (*end)
|
|
return -EINVAL;
|
|
retval = cft->write_s64(cgrp, cft, val);
|
|
}
|
|
if (!retval)
|
|
retval = nbytes;
|
|
return retval;
|
|
}
|
|
|
|
static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft,
|
|
struct file *file,
|
|
const char __user *userbuf,
|
|
size_t nbytes, loff_t *unused_ppos)
|
|
{
|
|
char local_buffer[CGROUP_LOCAL_BUFFER_SIZE];
|
|
int retval = 0;
|
|
size_t max_bytes = cft->max_write_len;
|
|
char *buffer = local_buffer;
|
|
|
|
if (!max_bytes)
|
|
max_bytes = sizeof(local_buffer) - 1;
|
|
if (nbytes >= max_bytes)
|
|
return -E2BIG;
|
|
/* Allocate a dynamic buffer if we need one */
|
|
if (nbytes >= sizeof(local_buffer)) {
|
|
buffer = kmalloc(nbytes + 1, GFP_KERNEL);
|
|
if (buffer == NULL)
|
|
return -ENOMEM;
|
|
}
|
|
if (nbytes && copy_from_user(buffer, userbuf, nbytes)) {
|
|
retval = -EFAULT;
|
|
goto out;
|
|
}
|
|
|
|
buffer[nbytes] = 0; /* nul-terminate */
|
|
retval = cft->write_string(cgrp, cft, strstrip(buffer));
|
|
if (!retval)
|
|
retval = nbytes;
|
|
out:
|
|
if (buffer != local_buffer)
|
|
kfree(buffer);
|
|
return retval;
|
|
}
|
|
|
|
static ssize_t cgroup_file_write(struct file *file, const char __user *buf,
|
|
size_t nbytes, loff_t *ppos)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
|
|
|
|
if (cgroup_is_dead(cgrp))
|
|
return -ENODEV;
|
|
if (cft->write)
|
|
return cft->write(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->write_u64 || cft->write_s64)
|
|
return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->write_string)
|
|
return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->trigger) {
|
|
int ret = cft->trigger(cgrp, (unsigned int)cft->private);
|
|
return ret ? ret : nbytes;
|
|
}
|
|
return -EINVAL;
|
|
}
|
|
|
|
static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft,
|
|
struct file *file,
|
|
char __user *buf, size_t nbytes,
|
|
loff_t *ppos)
|
|
{
|
|
char tmp[CGROUP_LOCAL_BUFFER_SIZE];
|
|
u64 val = cft->read_u64(cgrp, cft);
|
|
int len = sprintf(tmp, "%llu\n", (unsigned long long) val);
|
|
|
|
return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
|
|
}
|
|
|
|
static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft,
|
|
struct file *file,
|
|
char __user *buf, size_t nbytes,
|
|
loff_t *ppos)
|
|
{
|
|
char tmp[CGROUP_LOCAL_BUFFER_SIZE];
|
|
s64 val = cft->read_s64(cgrp, cft);
|
|
int len = sprintf(tmp, "%lld\n", (long long) val);
|
|
|
|
return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
|
|
}
|
|
|
|
static ssize_t cgroup_file_read(struct file *file, char __user *buf,
|
|
size_t nbytes, loff_t *ppos)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
|
|
|
|
if (cgroup_is_dead(cgrp))
|
|
return -ENODEV;
|
|
|
|
if (cft->read)
|
|
return cft->read(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->read_u64)
|
|
return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos);
|
|
if (cft->read_s64)
|
|
return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* seqfile ops/methods for returning structured data. Currently just
|
|
* supports string->u64 maps, but can be extended in future.
|
|
*/
|
|
|
|
struct cgroup_seqfile_state {
|
|
struct cftype *cft;
|
|
struct cgroup *cgroup;
|
|
};
|
|
|
|
static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value)
|
|
{
|
|
struct seq_file *sf = cb->state;
|
|
return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value);
|
|
}
|
|
|
|
static int cgroup_seqfile_show(struct seq_file *m, void *arg)
|
|
{
|
|
struct cgroup_seqfile_state *state = m->private;
|
|
struct cftype *cft = state->cft;
|
|
if (cft->read_map) {
|
|
struct cgroup_map_cb cb = {
|
|
.fill = cgroup_map_add,
|
|
.state = m,
|
|
};
|
|
return cft->read_map(state->cgroup, cft, &cb);
|
|
}
|
|
return cft->read_seq_string(state->cgroup, cft, m);
|
|
}
|
|
|
|
static int cgroup_seqfile_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct seq_file *seq = file->private_data;
|
|
kfree(seq->private);
|
|
return single_release(inode, file);
|
|
}
|
|
|
|
static const struct file_operations cgroup_seqfile_operations = {
|
|
.read = seq_read,
|
|
.write = cgroup_file_write,
|
|
.llseek = seq_lseek,
|
|
.release = cgroup_seqfile_release,
|
|
};
|
|
|
|
static int cgroup_file_open(struct inode *inode, struct file *file)
|
|
{
|
|
int err;
|
|
struct cftype *cft;
|
|
|
|
err = generic_file_open(inode, file);
|
|
if (err)
|
|
return err;
|
|
cft = __d_cft(file->f_dentry);
|
|
|
|
if (cft->read_map || cft->read_seq_string) {
|
|
struct cgroup_seqfile_state *state;
|
|
|
|
state = kzalloc(sizeof(*state), GFP_USER);
|
|
if (!state)
|
|
return -ENOMEM;
|
|
|
|
state->cft = cft;
|
|
state->cgroup = __d_cgrp(file->f_dentry->d_parent);
|
|
file->f_op = &cgroup_seqfile_operations;
|
|
err = single_open(file, cgroup_seqfile_show, state);
|
|
if (err < 0)
|
|
kfree(state);
|
|
} else if (cft->open)
|
|
err = cft->open(inode, file);
|
|
else
|
|
err = 0;
|
|
|
|
return err;
|
|
}
|
|
|
|
static int cgroup_file_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct cftype *cft = __d_cft(file->f_dentry);
|
|
if (cft->release)
|
|
return cft->release(inode, file);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* cgroup_rename - Only allow simple rename of directories in place.
|
|
*/
|
|
static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
int ret;
|
|
struct cgroup_name *name, *old_name;
|
|
struct cgroup *cgrp;
|
|
|
|
/*
|
|
* It's convinient to use parent dir's i_mutex to protected
|
|
* cgrp->name.
|
|
*/
|
|
lockdep_assert_held(&old_dir->i_mutex);
|
|
|
|
if (!S_ISDIR(old_dentry->d_inode->i_mode))
|
|
return -ENOTDIR;
|
|
if (new_dentry->d_inode)
|
|
return -EEXIST;
|
|
if (old_dir != new_dir)
|
|
return -EIO;
|
|
|
|
cgrp = __d_cgrp(old_dentry);
|
|
|
|
/*
|
|
* This isn't a proper migration and its usefulness is very
|
|
* limited. Disallow if sane_behavior.
|
|
*/
|
|
if (cgroup_sane_behavior(cgrp))
|
|
return -EPERM;
|
|
|
|
name = cgroup_alloc_name(new_dentry);
|
|
if (!name)
|
|
return -ENOMEM;
|
|
|
|
ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (ret) {
|
|
kfree(name);
|
|
return ret;
|
|
}
|
|
|
|
old_name = rcu_dereference_protected(cgrp->name, true);
|
|
rcu_assign_pointer(cgrp->name, name);
|
|
|
|
kfree_rcu(old_name, rcu_head);
|
|
return 0;
|
|
}
|
|
|
|
static struct simple_xattrs *__d_xattrs(struct dentry *dentry)
|
|
{
|
|
if (S_ISDIR(dentry->d_inode->i_mode))
|
|
return &__d_cgrp(dentry)->xattrs;
|
|
else
|
|
return &__d_cfe(dentry)->xattrs;
|
|
}
|
|
|
|
static inline int xattr_enabled(struct dentry *dentry)
|
|
{
|
|
struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
|
|
return root->flags & CGRP_ROOT_XATTR;
|
|
}
|
|
|
|
static bool is_valid_xattr(const char *name)
|
|
{
|
|
if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
|
|
!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
static int cgroup_setxattr(struct dentry *dentry, const char *name,
|
|
const void *val, size_t size, int flags)
|
|
{
|
|
if (!xattr_enabled(dentry))
|
|
return -EOPNOTSUPP;
|
|
if (!is_valid_xattr(name))
|
|
return -EINVAL;
|
|
return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags);
|
|
}
|
|
|
|
static int cgroup_removexattr(struct dentry *dentry, const char *name)
|
|
{
|
|
if (!xattr_enabled(dentry))
|
|
return -EOPNOTSUPP;
|
|
if (!is_valid_xattr(name))
|
|
return -EINVAL;
|
|
return simple_xattr_remove(__d_xattrs(dentry), name);
|
|
}
|
|
|
|
static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name,
|
|
void *buf, size_t size)
|
|
{
|
|
if (!xattr_enabled(dentry))
|
|
return -EOPNOTSUPP;
|
|
if (!is_valid_xattr(name))
|
|
return -EINVAL;
|
|
return simple_xattr_get(__d_xattrs(dentry), name, buf, size);
|
|
}
|
|
|
|
static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size)
|
|
{
|
|
if (!xattr_enabled(dentry))
|
|
return -EOPNOTSUPP;
|
|
return simple_xattr_list(__d_xattrs(dentry), buf, size);
|
|
}
|
|
|
|
static const struct file_operations cgroup_file_operations = {
|
|
.read = cgroup_file_read,
|
|
.write = cgroup_file_write,
|
|
.llseek = generic_file_llseek,
|
|
.open = cgroup_file_open,
|
|
.release = cgroup_file_release,
|
|
};
|
|
|
|
static const struct inode_operations cgroup_file_inode_operations = {
|
|
.setxattr = cgroup_setxattr,
|
|
.getxattr = cgroup_getxattr,
|
|
.listxattr = cgroup_listxattr,
|
|
.removexattr = cgroup_removexattr,
|
|
};
|
|
|
|
static const struct inode_operations cgroup_dir_inode_operations = {
|
|
.lookup = simple_lookup,
|
|
.mkdir = cgroup_mkdir,
|
|
.rmdir = cgroup_rmdir,
|
|
.rename = cgroup_rename,
|
|
.setxattr = cgroup_setxattr,
|
|
.getxattr = cgroup_getxattr,
|
|
.listxattr = cgroup_listxattr,
|
|
.removexattr = cgroup_removexattr,
|
|
};
|
|
|
|
/*
|
|
* Check if a file is a control file
|
|
*/
|
|
static inline struct cftype *__file_cft(struct file *file)
|
|
{
|
|
if (file_inode(file)->i_fop != &cgroup_file_operations)
|
|
return ERR_PTR(-EINVAL);
|
|
return __d_cft(file->f_dentry);
|
|
}
|
|
|
|
static int cgroup_create_file(struct dentry *dentry, umode_t mode,
|
|
struct super_block *sb)
|
|
{
|
|
struct inode *inode;
|
|
|
|
if (!dentry)
|
|
return -ENOENT;
|
|
if (dentry->d_inode)
|
|
return -EEXIST;
|
|
|
|
inode = cgroup_new_inode(mode, sb);
|
|
if (!inode)
|
|
return -ENOMEM;
|
|
|
|
if (S_ISDIR(mode)) {
|
|
inode->i_op = &cgroup_dir_inode_operations;
|
|
inode->i_fop = &simple_dir_operations;
|
|
|
|
/* start off with i_nlink == 2 (for "." entry) */
|
|
inc_nlink(inode);
|
|
inc_nlink(dentry->d_parent->d_inode);
|
|
|
|
/*
|
|
* Control reaches here with cgroup_mutex held.
|
|
* @inode->i_mutex should nest outside cgroup_mutex but we
|
|
* want to populate it immediately without releasing
|
|
* cgroup_mutex. As @inode isn't visible to anyone else
|
|
* yet, trylock will always succeed without affecting
|
|
* lockdep checks.
|
|
*/
|
|
WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex));
|
|
} else if (S_ISREG(mode)) {
|
|
inode->i_size = 0;
|
|
inode->i_fop = &cgroup_file_operations;
|
|
inode->i_op = &cgroup_file_inode_operations;
|
|
}
|
|
d_instantiate(dentry, inode);
|
|
dget(dentry); /* Extra count - pin the dentry in core */
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_file_mode - deduce file mode of a control file
|
|
* @cft: the control file in question
|
|
*
|
|
* returns cft->mode if ->mode is not 0
|
|
* returns S_IRUGO|S_IWUSR if it has both a read and a write handler
|
|
* returns S_IRUGO if it has only a read handler
|
|
* returns S_IWUSR if it has only a write hander
|
|
*/
|
|
static umode_t cgroup_file_mode(const struct cftype *cft)
|
|
{
|
|
umode_t mode = 0;
|
|
|
|
if (cft->mode)
|
|
return cft->mode;
|
|
|
|
if (cft->read || cft->read_u64 || cft->read_s64 ||
|
|
cft->read_map || cft->read_seq_string)
|
|
mode |= S_IRUGO;
|
|
|
|
if (cft->write || cft->write_u64 || cft->write_s64 ||
|
|
cft->write_string || cft->trigger)
|
|
mode |= S_IWUSR;
|
|
|
|
return mode;
|
|
}
|
|
|
|
static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
|
|
struct cftype *cft)
|
|
{
|
|
struct dentry *dir = cgrp->dentry;
|
|
struct cgroup *parent = __d_cgrp(dir);
|
|
struct dentry *dentry;
|
|
struct cfent *cfe;
|
|
int error;
|
|
umode_t mode;
|
|
char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
|
|
|
|
if (subsys && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
|
|
strcpy(name, subsys->name);
|
|
strcat(name, ".");
|
|
}
|
|
strcat(name, cft->name);
|
|
|
|
BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
|
|
|
|
cfe = kzalloc(sizeof(*cfe), GFP_KERNEL);
|
|
if (!cfe)
|
|
return -ENOMEM;
|
|
|
|
dentry = lookup_one_len(name, dir, strlen(name));
|
|
if (IS_ERR(dentry)) {
|
|
error = PTR_ERR(dentry);
|
|
goto out;
|
|
}
|
|
|
|
cfe->type = (void *)cft;
|
|
cfe->dentry = dentry;
|
|
dentry->d_fsdata = cfe;
|
|
simple_xattrs_init(&cfe->xattrs);
|
|
|
|
mode = cgroup_file_mode(cft);
|
|
error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb);
|
|
if (!error) {
|
|
list_add_tail(&cfe->node, &parent->files);
|
|
cfe = NULL;
|
|
}
|
|
dput(dentry);
|
|
out:
|
|
kfree(cfe);
|
|
return error;
|
|
}
|
|
|
|
static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
|
|
struct cftype cfts[], bool is_add)
|
|
{
|
|
struct cftype *cft;
|
|
int err, ret = 0;
|
|
|
|
for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
|
/* does cft->flags tell us to skip this file on @cgrp? */
|
|
if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp))
|
|
continue;
|
|
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
|
|
continue;
|
|
if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
|
|
continue;
|
|
|
|
if (is_add) {
|
|
err = cgroup_add_file(cgrp, subsys, cft);
|
|
if (err)
|
|
pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
|
|
cft->name, err);
|
|
ret = err;
|
|
} else {
|
|
cgroup_rm_file(cgrp, cft);
|
|
}
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static void cgroup_cfts_prepare(void)
|
|
__acquires(&cgroup_mutex)
|
|
{
|
|
/*
|
|
* Thanks to the entanglement with vfs inode locking, we can't walk
|
|
* the existing cgroups under cgroup_mutex and create files.
|
|
* Instead, we use cgroup_for_each_descendant_pre() and drop RCU
|
|
* read lock before calling cgroup_addrm_files().
|
|
*/
|
|
mutex_lock(&cgroup_mutex);
|
|
}
|
|
|
|
static void cgroup_cfts_commit(struct cgroup_subsys *ss,
|
|
struct cftype *cfts, bool is_add)
|
|
__releases(&cgroup_mutex)
|
|
{
|
|
LIST_HEAD(pending);
|
|
struct cgroup *cgrp, *root = &ss->root->top_cgroup;
|
|
struct super_block *sb = ss->root->sb;
|
|
struct dentry *prev = NULL;
|
|
struct inode *inode;
|
|
u64 update_before;
|
|
|
|
/* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
|
|
if (!cfts || ss->root == &cgroup_dummy_root ||
|
|
!atomic_inc_not_zero(&sb->s_active)) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* All cgroups which are created after we drop cgroup_mutex will
|
|
* have the updated set of files, so we only need to update the
|
|
* cgroups created before the current @cgroup_serial_nr_next.
|
|
*/
|
|
update_before = cgroup_serial_nr_next;
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/* @root always needs to be updated */
|
|
inode = root->dentry->d_inode;
|
|
mutex_lock(&inode->i_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
cgroup_addrm_files(root, ss, cfts, is_add);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
/* add/rm files for all cgroups created before */
|
|
rcu_read_lock();
|
|
cgroup_for_each_descendant_pre(cgrp, root) {
|
|
if (cgroup_is_dead(cgrp))
|
|
continue;
|
|
|
|
inode = cgrp->dentry->d_inode;
|
|
dget(cgrp->dentry);
|
|
rcu_read_unlock();
|
|
|
|
dput(prev);
|
|
prev = cgrp->dentry;
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp))
|
|
cgroup_addrm_files(cgrp, ss, cfts, is_add);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
rcu_read_lock();
|
|
}
|
|
rcu_read_unlock();
|
|
dput(prev);
|
|
deactivate_super(sb);
|
|
}
|
|
|
|
/**
|
|
* cgroup_add_cftypes - add an array of cftypes to a subsystem
|
|
* @ss: target cgroup subsystem
|
|
* @cfts: zero-length name terminated array of cftypes
|
|
*
|
|
* Register @cfts to @ss. Files described by @cfts are created for all
|
|
* existing cgroups to which @ss is attached and all future cgroups will
|
|
* have them too. This function can be called anytime whether @ss is
|
|
* attached or not.
|
|
*
|
|
* Returns 0 on successful registration, -errno on failure. Note that this
|
|
* function currently returns 0 as long as @cfts registration is successful
|
|
* even if some file creation attempts on existing cgroups fail.
|
|
*/
|
|
int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
|
{
|
|
struct cftype_set *set;
|
|
|
|
set = kzalloc(sizeof(*set), GFP_KERNEL);
|
|
if (!set)
|
|
return -ENOMEM;
|
|
|
|
cgroup_cfts_prepare();
|
|
set->cfts = cfts;
|
|
list_add_tail(&set->node, &ss->cftsets);
|
|
cgroup_cfts_commit(ss, cfts, true);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
|
|
|
|
/**
|
|
* cgroup_rm_cftypes - remove an array of cftypes from a subsystem
|
|
* @ss: target cgroup subsystem
|
|
* @cfts: zero-length name terminated array of cftypes
|
|
*
|
|
* Unregister @cfts from @ss. Files described by @cfts are removed from
|
|
* all existing cgroups to which @ss is attached and all future cgroups
|
|
* won't have them either. This function can be called anytime whether @ss
|
|
* is attached or not.
|
|
*
|
|
* Returns 0 on successful unregistration, -ENOENT if @cfts is not
|
|
* registered with @ss.
|
|
*/
|
|
int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
|
{
|
|
struct cftype_set *set;
|
|
|
|
cgroup_cfts_prepare();
|
|
|
|
list_for_each_entry(set, &ss->cftsets, node) {
|
|
if (set->cfts == cfts) {
|
|
list_del(&set->node);
|
|
kfree(set);
|
|
cgroup_cfts_commit(ss, cfts, false);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
cgroup_cfts_commit(ss, NULL, false);
|
|
return -ENOENT;
|
|
}
|
|
|
|
/**
|
|
* cgroup_task_count - count the number of tasks in a cgroup.
|
|
* @cgrp: the cgroup in question
|
|
*
|
|
* Return the number of tasks in the cgroup.
|
|
*/
|
|
int cgroup_task_count(const struct cgroup *cgrp)
|
|
{
|
|
int count = 0;
|
|
struct cgrp_cset_link *link;
|
|
|
|
read_lock(&css_set_lock);
|
|
list_for_each_entry(link, &cgrp->cset_links, cset_link)
|
|
count += atomic_read(&link->cset->refcount);
|
|
read_unlock(&css_set_lock);
|
|
return count;
|
|
}
|
|
|
|
/*
|
|
* Advance a list_head iterator. The iterator should be positioned at
|
|
* the start of a css_set
|
|
*/
|
|
static void cgroup_advance_iter(struct cgroup *cgrp, struct cgroup_iter *it)
|
|
{
|
|
struct list_head *l = it->cset_link;
|
|
struct cgrp_cset_link *link;
|
|
struct css_set *cset;
|
|
|
|
/* Advance to the next non-empty css_set */
|
|
do {
|
|
l = l->next;
|
|
if (l == &cgrp->cset_links) {
|
|
it->cset_link = NULL;
|
|
return;
|
|
}
|
|
link = list_entry(l, struct cgrp_cset_link, cset_link);
|
|
cset = link->cset;
|
|
} while (list_empty(&cset->tasks));
|
|
it->cset_link = l;
|
|
it->task = cset->tasks.next;
|
|
}
|
|
|
|
/*
|
|
* To reduce the fork() overhead for systems that are not actually
|
|
* using their cgroups capability, we don't maintain the lists running
|
|
* through each css_set to its tasks until we see the list actually
|
|
* used - in other words after the first call to cgroup_iter_start().
|
|
*/
|
|
static void cgroup_enable_task_cg_lists(void)
|
|
{
|
|
struct task_struct *p, *g;
|
|
write_lock(&css_set_lock);
|
|
use_task_css_set_links = 1;
|
|
/*
|
|
* We need tasklist_lock because RCU is not safe against
|
|
* while_each_thread(). Besides, a forking task that has passed
|
|
* cgroup_post_fork() without seeing use_task_css_set_links = 1
|
|
* is not guaranteed to have its child immediately visible in the
|
|
* tasklist if we walk through it with RCU.
|
|
*/
|
|
read_lock(&tasklist_lock);
|
|
do_each_thread(g, p) {
|
|
task_lock(p);
|
|
/*
|
|
* We should check if the process is exiting, otherwise
|
|
* it will race with cgroup_exit() in that the list
|
|
* entry won't be deleted though the process has exited.
|
|
*/
|
|
if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list))
|
|
list_add(&p->cg_list, &task_css_set(p)->tasks);
|
|
task_unlock(p);
|
|
} while_each_thread(g, p);
|
|
read_unlock(&tasklist_lock);
|
|
write_unlock(&css_set_lock);
|
|
}
|
|
|
|
/**
|
|
* cgroup_next_sibling - find the next sibling of a given cgroup
|
|
* @pos: the current cgroup
|
|
*
|
|
* This function returns the next sibling of @pos and should be called
|
|
* under RCU read lock. The only requirement is that @pos is accessible.
|
|
* The next sibling is guaranteed to be returned regardless of @pos's
|
|
* state.
|
|
*/
|
|
struct cgroup *cgroup_next_sibling(struct cgroup *pos)
|
|
{
|
|
struct cgroup *next;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
/*
|
|
* @pos could already have been removed. Once a cgroup is removed,
|
|
* its ->sibling.next is no longer updated when its next sibling
|
|
* changes. As CGRP_DEAD assertion is serialized and happens
|
|
* before the cgroup is taken off the ->sibling list, if we see it
|
|
* unasserted, it's guaranteed that the next sibling hasn't
|
|
* finished its grace period even if it's already removed, and thus
|
|
* safe to dereference from this RCU critical section. If
|
|
* ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed
|
|
* to be visible as %true here.
|
|
*/
|
|
if (likely(!cgroup_is_dead(pos))) {
|
|
next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling);
|
|
if (&next->sibling != &pos->parent->children)
|
|
return next;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Can't dereference the next pointer. Each cgroup is given a
|
|
* monotonically increasing unique serial number and always
|
|
* appended to the sibling list, so the next one can be found by
|
|
* walking the parent's children until we see a cgroup with higher
|
|
* serial number than @pos's.
|
|
*
|
|
* While this path can be slow, it's taken only when either the
|
|
* current cgroup is removed or iteration and removal race.
|
|
*/
|
|
list_for_each_entry_rcu(next, &pos->parent->children, sibling)
|
|
if (next->serial_nr > pos->serial_nr)
|
|
return next;
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_next_sibling);
|
|
|
|
/**
|
|
* cgroup_next_descendant_pre - find the next descendant for pre-order walk
|
|
* @pos: the current position (%NULL to initiate traversal)
|
|
* @cgroup: cgroup whose descendants to walk
|
|
*
|
|
* To be used by cgroup_for_each_descendant_pre(). Find the next
|
|
* descendant to visit for pre-order traversal of @cgroup's descendants.
|
|
*
|
|
* While this function requires RCU read locking, it doesn't require the
|
|
* whole traversal to be contained in a single RCU critical section. This
|
|
* function will return the correct next descendant as long as both @pos
|
|
* and @cgroup are accessible and @pos is a descendant of @cgroup.
|
|
*/
|
|
struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
|
|
struct cgroup *cgroup)
|
|
{
|
|
struct cgroup *next;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
/* if first iteration, pretend we just visited @cgroup */
|
|
if (!pos)
|
|
pos = cgroup;
|
|
|
|
/* visit the first child if exists */
|
|
next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling);
|
|
if (next)
|
|
return next;
|
|
|
|
/* no child, visit my or the closest ancestor's next sibling */
|
|
while (pos != cgroup) {
|
|
next = cgroup_next_sibling(pos);
|
|
if (next)
|
|
return next;
|
|
pos = pos->parent;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre);
|
|
|
|
/**
|
|
* cgroup_rightmost_descendant - return the rightmost descendant of a cgroup
|
|
* @pos: cgroup of interest
|
|
*
|
|
* Return the rightmost descendant of @pos. If there's no descendant,
|
|
* @pos is returned. This can be used during pre-order traversal to skip
|
|
* subtree of @pos.
|
|
*
|
|
* While this function requires RCU read locking, it doesn't require the
|
|
* whole traversal to be contained in a single RCU critical section. This
|
|
* function will return the correct rightmost descendant as long as @pos is
|
|
* accessible.
|
|
*/
|
|
struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos)
|
|
{
|
|
struct cgroup *last, *tmp;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
do {
|
|
last = pos;
|
|
/* ->prev isn't RCU safe, walk ->next till the end */
|
|
pos = NULL;
|
|
list_for_each_entry_rcu(tmp, &last->children, sibling)
|
|
pos = tmp;
|
|
} while (pos);
|
|
|
|
return last;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant);
|
|
|
|
static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos)
|
|
{
|
|
struct cgroup *last;
|
|
|
|
do {
|
|
last = pos;
|
|
pos = list_first_or_null_rcu(&pos->children, struct cgroup,
|
|
sibling);
|
|
} while (pos);
|
|
|
|
return last;
|
|
}
|
|
|
|
/**
|
|
* cgroup_next_descendant_post - find the next descendant for post-order walk
|
|
* @pos: the current position (%NULL to initiate traversal)
|
|
* @cgroup: cgroup whose descendants to walk
|
|
*
|
|
* To be used by cgroup_for_each_descendant_post(). Find the next
|
|
* descendant to visit for post-order traversal of @cgroup's descendants.
|
|
*
|
|
* While this function requires RCU read locking, it doesn't require the
|
|
* whole traversal to be contained in a single RCU critical section. This
|
|
* function will return the correct next descendant as long as both @pos
|
|
* and @cgroup are accessible and @pos is a descendant of @cgroup.
|
|
*/
|
|
struct cgroup *cgroup_next_descendant_post(struct cgroup *pos,
|
|
struct cgroup *cgroup)
|
|
{
|
|
struct cgroup *next;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
/* if first iteration, visit the leftmost descendant */
|
|
if (!pos) {
|
|
next = cgroup_leftmost_descendant(cgroup);
|
|
return next != cgroup ? next : NULL;
|
|
}
|
|
|
|
/* if there's an unvisited sibling, visit its leftmost descendant */
|
|
next = cgroup_next_sibling(pos);
|
|
if (next)
|
|
return cgroup_leftmost_descendant(next);
|
|
|
|
/* no sibling left, visit parent */
|
|
next = pos->parent;
|
|
return next != cgroup ? next : NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_next_descendant_post);
|
|
|
|
void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it)
|
|
__acquires(css_set_lock)
|
|
{
|
|
/*
|
|
* The first time anyone tries to iterate across a cgroup,
|
|
* we need to enable the list linking each css_set to its
|
|
* tasks, and fix up all existing tasks.
|
|
*/
|
|
if (!use_task_css_set_links)
|
|
cgroup_enable_task_cg_lists();
|
|
|
|
read_lock(&css_set_lock);
|
|
it->cset_link = &cgrp->cset_links;
|
|
cgroup_advance_iter(cgrp, it);
|
|
}
|
|
|
|
struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
|
|
struct cgroup_iter *it)
|
|
{
|
|
struct task_struct *res;
|
|
struct list_head *l = it->task;
|
|
struct cgrp_cset_link *link;
|
|
|
|
/* If the iterator cg is NULL, we have no tasks */
|
|
if (!it->cset_link)
|
|
return NULL;
|
|
res = list_entry(l, struct task_struct, cg_list);
|
|
/* Advance iterator to find next entry */
|
|
l = l->next;
|
|
link = list_entry(it->cset_link, struct cgrp_cset_link, cset_link);
|
|
if (l == &link->cset->tasks) {
|
|
/* We reached the end of this task list - move on to
|
|
* the next cg_cgroup_link */
|
|
cgroup_advance_iter(cgrp, it);
|
|
} else {
|
|
it->task = l;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it)
|
|
__releases(css_set_lock)
|
|
{
|
|
read_unlock(&css_set_lock);
|
|
}
|
|
|
|
static inline int started_after_time(struct task_struct *t1,
|
|
struct timespec *time,
|
|
struct task_struct *t2)
|
|
{
|
|
int start_diff = timespec_compare(&t1->start_time, time);
|
|
if (start_diff > 0) {
|
|
return 1;
|
|
} else if (start_diff < 0) {
|
|
return 0;
|
|
} else {
|
|
/*
|
|
* Arbitrarily, if two processes started at the same
|
|
* time, we'll say that the lower pointer value
|
|
* started first. Note that t2 may have exited by now
|
|
* so this may not be a valid pointer any longer, but
|
|
* that's fine - it still serves to distinguish
|
|
* between two tasks started (effectively) simultaneously.
|
|
*/
|
|
return t1 > t2;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This function is a callback from heap_insert() and is used to order
|
|
* the heap.
|
|
* In this case we order the heap in descending task start time.
|
|
*/
|
|
static inline int started_after(void *p1, void *p2)
|
|
{
|
|
struct task_struct *t1 = p1;
|
|
struct task_struct *t2 = p2;
|
|
return started_after_time(t1, &t2->start_time, t2);
|
|
}
|
|
|
|
/**
|
|
* cgroup_scan_tasks - iterate though all the tasks in a cgroup
|
|
* @scan: struct cgroup_scanner containing arguments for the scan
|
|
*
|
|
* Arguments include pointers to callback functions test_task() and
|
|
* process_task().
|
|
* Iterate through all the tasks in a cgroup, calling test_task() for each,
|
|
* and if it returns true, call process_task() for it also.
|
|
* The test_task pointer may be NULL, meaning always true (select all tasks).
|
|
* Effectively duplicates cgroup_iter_{start,next,end}()
|
|
* but does not lock css_set_lock for the call to process_task().
|
|
* The struct cgroup_scanner may be embedded in any structure of the caller's
|
|
* creation.
|
|
* It is guaranteed that process_task() will act on every task that
|
|
* is a member of the cgroup for the duration of this call. This
|
|
* function may or may not call process_task() for tasks that exit
|
|
* or move to a different cgroup during the call, or are forked or
|
|
* move into the cgroup during the call.
|
|
*
|
|
* Note that test_task() may be called with locks held, and may in some
|
|
* situations be called multiple times for the same task, so it should
|
|
* be cheap.
|
|
* If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
|
|
* pre-allocated and will be used for heap operations (and its "gt" member will
|
|
* be overwritten), else a temporary heap will be used (allocation of which
|
|
* may cause this function to fail).
|
|
*/
|
|
int cgroup_scan_tasks(struct cgroup_scanner *scan)
|
|
{
|
|
int retval, i;
|
|
struct cgroup_iter it;
|
|
struct task_struct *p, *dropped;
|
|
/* Never dereference latest_task, since it's not refcounted */
|
|
struct task_struct *latest_task = NULL;
|
|
struct ptr_heap tmp_heap;
|
|
struct ptr_heap *heap;
|
|
struct timespec latest_time = { 0, 0 };
|
|
|
|
if (scan->heap) {
|
|
/* The caller supplied our heap and pre-allocated its memory */
|
|
heap = scan->heap;
|
|
heap->gt = &started_after;
|
|
} else {
|
|
/* We need to allocate our own heap memory */
|
|
heap = &tmp_heap;
|
|
retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after);
|
|
if (retval)
|
|
/* cannot allocate the heap */
|
|
return retval;
|
|
}
|
|
|
|
again:
|
|
/*
|
|
* Scan tasks in the cgroup, using the scanner's "test_task" callback
|
|
* to determine which are of interest, and using the scanner's
|
|
* "process_task" callback to process any of them that need an update.
|
|
* Since we don't want to hold any locks during the task updates,
|
|
* gather tasks to be processed in a heap structure.
|
|
* The heap is sorted by descending task start time.
|
|
* If the statically-sized heap fills up, we overflow tasks that
|
|
* started later, and in future iterations only consider tasks that
|
|
* started after the latest task in the previous pass. This
|
|
* guarantees forward progress and that we don't miss any tasks.
|
|
*/
|
|
heap->size = 0;
|
|
cgroup_iter_start(scan->cg, &it);
|
|
while ((p = cgroup_iter_next(scan->cg, &it))) {
|
|
/*
|
|
* Only affect tasks that qualify per the caller's callback,
|
|
* if he provided one
|
|
*/
|
|
if (scan->test_task && !scan->test_task(p, scan))
|
|
continue;
|
|
/*
|
|
* Only process tasks that started after the last task
|
|
* we processed
|
|
*/
|
|
if (!started_after_time(p, &latest_time, latest_task))
|
|
continue;
|
|
dropped = heap_insert(heap, p);
|
|
if (dropped == NULL) {
|
|
/*
|
|
* The new task was inserted; the heap wasn't
|
|
* previously full
|
|
*/
|
|
get_task_struct(p);
|
|
} else if (dropped != p) {
|
|
/*
|
|
* The new task was inserted, and pushed out a
|
|
* different task
|
|
*/
|
|
get_task_struct(p);
|
|
put_task_struct(dropped);
|
|
}
|
|
/*
|
|
* Else the new task was newer than anything already in
|
|
* the heap and wasn't inserted
|
|
*/
|
|
}
|
|
cgroup_iter_end(scan->cg, &it);
|
|
|
|
if (heap->size) {
|
|
for (i = 0; i < heap->size; i++) {
|
|
struct task_struct *q = heap->ptrs[i];
|
|
if (i == 0) {
|
|
latest_time = q->start_time;
|
|
latest_task = q;
|
|
}
|
|
/* Process the task per the caller's callback */
|
|
scan->process_task(q, scan);
|
|
put_task_struct(q);
|
|
}
|
|
/*
|
|
* If we had to process any tasks at all, scan again
|
|
* in case some of them were in the middle of forking
|
|
* children that didn't get processed.
|
|
* Not the most efficient way to do it, but it avoids
|
|
* having to take callback_mutex in the fork path
|
|
*/
|
|
goto again;
|
|
}
|
|
if (heap == &tmp_heap)
|
|
heap_free(&tmp_heap);
|
|
return 0;
|
|
}
|
|
|
|
static void cgroup_transfer_one_task(struct task_struct *task,
|
|
struct cgroup_scanner *scan)
|
|
{
|
|
struct cgroup *new_cgroup = scan->data;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
cgroup_attach_task(new_cgroup, task, false);
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
/**
|
|
* cgroup_trasnsfer_tasks - move tasks from one cgroup to another
|
|
* @to: cgroup to which the tasks will be moved
|
|
* @from: cgroup in which the tasks currently reside
|
|
*/
|
|
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
|
|
{
|
|
struct cgroup_scanner scan;
|
|
|
|
scan.cg = from;
|
|
scan.test_task = NULL; /* select all tasks in cgroup */
|
|
scan.process_task = cgroup_transfer_one_task;
|
|
scan.heap = NULL;
|
|
scan.data = to;
|
|
|
|
return cgroup_scan_tasks(&scan);
|
|
}
|
|
|
|
/*
|
|
* Stuff for reading the 'tasks'/'procs' files.
|
|
*
|
|
* Reading this file can return large amounts of data if a cgroup has
|
|
* *lots* of attached tasks. So it may need several calls to read(),
|
|
* but we cannot guarantee that the information we produce is correct
|
|
* unless we produce it entirely atomically.
|
|
*
|
|
*/
|
|
|
|
/* which pidlist file are we talking about? */
|
|
enum cgroup_filetype {
|
|
CGROUP_FILE_PROCS,
|
|
CGROUP_FILE_TASKS,
|
|
};
|
|
|
|
/*
|
|
* A pidlist is a list of pids that virtually represents the contents of one
|
|
* of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
|
|
* a pair (one each for procs, tasks) for each pid namespace that's relevant
|
|
* to the cgroup.
|
|
*/
|
|
struct cgroup_pidlist {
|
|
/*
|
|
* used to find which pidlist is wanted. doesn't change as long as
|
|
* this particular list stays in the list.
|
|
*/
|
|
struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
|
|
/* array of xids */
|
|
pid_t *list;
|
|
/* how many elements the above list has */
|
|
int length;
|
|
/* how many files are using the current array */
|
|
int use_count;
|
|
/* each of these stored in a list by its cgroup */
|
|
struct list_head links;
|
|
/* pointer to the cgroup we belong to, for list removal purposes */
|
|
struct cgroup *owner;
|
|
/* protects the other fields */
|
|
struct rw_semaphore mutex;
|
|
};
|
|
|
|
/*
|
|
* The following two functions "fix" the issue where there are more pids
|
|
* than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
|
|
* TODO: replace with a kernel-wide solution to this problem
|
|
*/
|
|
#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
|
|
static void *pidlist_allocate(int count)
|
|
{
|
|
if (PIDLIST_TOO_LARGE(count))
|
|
return vmalloc(count * sizeof(pid_t));
|
|
else
|
|
return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
|
|
}
|
|
static void pidlist_free(void *p)
|
|
{
|
|
if (is_vmalloc_addr(p))
|
|
vfree(p);
|
|
else
|
|
kfree(p);
|
|
}
|
|
|
|
/*
|
|
* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
|
|
* Returns the number of unique elements.
|
|
*/
|
|
static int pidlist_uniq(pid_t *list, int length)
|
|
{
|
|
int src, dest = 1;
|
|
|
|
/*
|
|
* we presume the 0th element is unique, so i starts at 1. trivial
|
|
* edge cases first; no work needs to be done for either
|
|
*/
|
|
if (length == 0 || length == 1)
|
|
return length;
|
|
/* src and dest walk down the list; dest counts unique elements */
|
|
for (src = 1; src < length; src++) {
|
|
/* find next unique element */
|
|
while (list[src] == list[src-1]) {
|
|
src++;
|
|
if (src == length)
|
|
goto after;
|
|
}
|
|
/* dest always points to where the next unique element goes */
|
|
list[dest] = list[src];
|
|
dest++;
|
|
}
|
|
after:
|
|
return dest;
|
|
}
|
|
|
|
static int cmppid(const void *a, const void *b)
|
|
{
|
|
return *(pid_t *)a - *(pid_t *)b;
|
|
}
|
|
|
|
/*
|
|
* find the appropriate pidlist for our purpose (given procs vs tasks)
|
|
* returns with the lock on that pidlist already held, and takes care
|
|
* of the use count, or returns NULL with no locks held if we're out of
|
|
* memory.
|
|
*/
|
|
static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
|
|
enum cgroup_filetype type)
|
|
{
|
|
struct cgroup_pidlist *l;
|
|
/* don't need task_nsproxy() if we're looking at ourself */
|
|
struct pid_namespace *ns = task_active_pid_ns(current);
|
|
|
|
/*
|
|
* We can't drop the pidlist_mutex before taking the l->mutex in case
|
|
* the last ref-holder is trying to remove l from the list at the same
|
|
* time. Holding the pidlist_mutex precludes somebody taking whichever
|
|
* list we find out from under us - compare release_pid_array().
|
|
*/
|
|
mutex_lock(&cgrp->pidlist_mutex);
|
|
list_for_each_entry(l, &cgrp->pidlists, links) {
|
|
if (l->key.type == type && l->key.ns == ns) {
|
|
/* make sure l doesn't vanish out from under us */
|
|
down_write(&l->mutex);
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
return l;
|
|
}
|
|
}
|
|
/* entry not found; create a new one */
|
|
l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
|
|
if (!l) {
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
return l;
|
|
}
|
|
init_rwsem(&l->mutex);
|
|
down_write(&l->mutex);
|
|
l->key.type = type;
|
|
l->key.ns = get_pid_ns(ns);
|
|
l->owner = cgrp;
|
|
list_add(&l->links, &cgrp->pidlists);
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
return l;
|
|
}
|
|
|
|
/*
|
|
* Load a cgroup's pidarray with either procs' tgids or tasks' pids
|
|
*/
|
|
static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
|
|
struct cgroup_pidlist **lp)
|
|
{
|
|
pid_t *array;
|
|
int length;
|
|
int pid, n = 0; /* used for populating the array */
|
|
struct cgroup_iter it;
|
|
struct task_struct *tsk;
|
|
struct cgroup_pidlist *l;
|
|
|
|
/*
|
|
* If cgroup gets more users after we read count, we won't have
|
|
* enough space - tough. This race is indistinguishable to the
|
|
* caller from the case that the additional cgroup users didn't
|
|
* show up until sometime later on.
|
|
*/
|
|
length = cgroup_task_count(cgrp);
|
|
array = pidlist_allocate(length);
|
|
if (!array)
|
|
return -ENOMEM;
|
|
/* now, populate the array */
|
|
cgroup_iter_start(cgrp, &it);
|
|
while ((tsk = cgroup_iter_next(cgrp, &it))) {
|
|
if (unlikely(n == length))
|
|
break;
|
|
/* get tgid or pid for procs or tasks file respectively */
|
|
if (type == CGROUP_FILE_PROCS)
|
|
pid = task_tgid_vnr(tsk);
|
|
else
|
|
pid = task_pid_vnr(tsk);
|
|
if (pid > 0) /* make sure to only use valid results */
|
|
array[n++] = pid;
|
|
}
|
|
cgroup_iter_end(cgrp, &it);
|
|
length = n;
|
|
/* now sort & (if procs) strip out duplicates */
|
|
sort(array, length, sizeof(pid_t), cmppid, NULL);
|
|
if (type == CGROUP_FILE_PROCS)
|
|
length = pidlist_uniq(array, length);
|
|
l = cgroup_pidlist_find(cgrp, type);
|
|
if (!l) {
|
|
pidlist_free(array);
|
|
return -ENOMEM;
|
|
}
|
|
/* store array, freeing old if necessary - lock already held */
|
|
pidlist_free(l->list);
|
|
l->list = array;
|
|
l->length = length;
|
|
l->use_count++;
|
|
up_write(&l->mutex);
|
|
*lp = l;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroupstats_build - build and fill cgroupstats
|
|
* @stats: cgroupstats to fill information into
|
|
* @dentry: A dentry entry belonging to the cgroup for which stats have
|
|
* been requested.
|
|
*
|
|
* Build and fill cgroupstats so that taskstats can export it to user
|
|
* space.
|
|
*/
|
|
int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
|
|
{
|
|
int ret = -EINVAL;
|
|
struct cgroup *cgrp;
|
|
struct cgroup_iter it;
|
|
struct task_struct *tsk;
|
|
|
|
/*
|
|
* Validate dentry by checking the superblock operations,
|
|
* and make sure it's a directory.
|
|
*/
|
|
if (dentry->d_sb->s_op != &cgroup_ops ||
|
|
!S_ISDIR(dentry->d_inode->i_mode))
|
|
goto err;
|
|
|
|
ret = 0;
|
|
cgrp = dentry->d_fsdata;
|
|
|
|
cgroup_iter_start(cgrp, &it);
|
|
while ((tsk = cgroup_iter_next(cgrp, &it))) {
|
|
switch (tsk->state) {
|
|
case TASK_RUNNING:
|
|
stats->nr_running++;
|
|
break;
|
|
case TASK_INTERRUPTIBLE:
|
|
stats->nr_sleeping++;
|
|
break;
|
|
case TASK_UNINTERRUPTIBLE:
|
|
stats->nr_uninterruptible++;
|
|
break;
|
|
case TASK_STOPPED:
|
|
stats->nr_stopped++;
|
|
break;
|
|
default:
|
|
if (delayacct_is_task_waiting_on_io(tsk))
|
|
stats->nr_io_wait++;
|
|
break;
|
|
}
|
|
}
|
|
cgroup_iter_end(cgrp, &it);
|
|
|
|
err:
|
|
return ret;
|
|
}
|
|
|
|
|
|
/*
|
|
* seq_file methods for the tasks/procs files. The seq_file position is the
|
|
* next pid to display; the seq_file iterator is a pointer to the pid
|
|
* in the cgroup->l->list array.
|
|
*/
|
|
|
|
static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
|
|
{
|
|
/*
|
|
* Initially we receive a position value that corresponds to
|
|
* one more than the last pid shown (or 0 on the first call or
|
|
* after a seek to the start). Use a binary-search to find the
|
|
* next pid to display, if any
|
|
*/
|
|
struct cgroup_pidlist *l = s->private;
|
|
int index = 0, pid = *pos;
|
|
int *iter;
|
|
|
|
down_read(&l->mutex);
|
|
if (pid) {
|
|
int end = l->length;
|
|
|
|
while (index < end) {
|
|
int mid = (index + end) / 2;
|
|
if (l->list[mid] == pid) {
|
|
index = mid;
|
|
break;
|
|
} else if (l->list[mid] <= pid)
|
|
index = mid + 1;
|
|
else
|
|
end = mid;
|
|
}
|
|
}
|
|
/* If we're off the end of the array, we're done */
|
|
if (index >= l->length)
|
|
return NULL;
|
|
/* Update the abstract position to be the actual pid that we found */
|
|
iter = l->list + index;
|
|
*pos = *iter;
|
|
return iter;
|
|
}
|
|
|
|
static void cgroup_pidlist_stop(struct seq_file *s, void *v)
|
|
{
|
|
struct cgroup_pidlist *l = s->private;
|
|
up_read(&l->mutex);
|
|
}
|
|
|
|
static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
|
|
{
|
|
struct cgroup_pidlist *l = s->private;
|
|
pid_t *p = v;
|
|
pid_t *end = l->list + l->length;
|
|
/*
|
|
* Advance to the next pid in the array. If this goes off the
|
|
* end, we're done
|
|
*/
|
|
p++;
|
|
if (p >= end) {
|
|
return NULL;
|
|
} else {
|
|
*pos = *p;
|
|
return p;
|
|
}
|
|
}
|
|
|
|
static int cgroup_pidlist_show(struct seq_file *s, void *v)
|
|
{
|
|
return seq_printf(s, "%d\n", *(int *)v);
|
|
}
|
|
|
|
/*
|
|
* seq_operations functions for iterating on pidlists through seq_file -
|
|
* independent of whether it's tasks or procs
|
|
*/
|
|
static const struct seq_operations cgroup_pidlist_seq_operations = {
|
|
.start = cgroup_pidlist_start,
|
|
.stop = cgroup_pidlist_stop,
|
|
.next = cgroup_pidlist_next,
|
|
.show = cgroup_pidlist_show,
|
|
};
|
|
|
|
static void cgroup_release_pid_array(struct cgroup_pidlist *l)
|
|
{
|
|
/*
|
|
* the case where we're the last user of this particular pidlist will
|
|
* have us remove it from the cgroup's list, which entails taking the
|
|
* mutex. since in pidlist_find the pidlist->lock depends on cgroup->
|
|
* pidlist_mutex, we have to take pidlist_mutex first.
|
|
*/
|
|
mutex_lock(&l->owner->pidlist_mutex);
|
|
down_write(&l->mutex);
|
|
BUG_ON(!l->use_count);
|
|
if (!--l->use_count) {
|
|
/* we're the last user if refcount is 0; remove and free */
|
|
list_del(&l->links);
|
|
mutex_unlock(&l->owner->pidlist_mutex);
|
|
pidlist_free(l->list);
|
|
put_pid_ns(l->key.ns);
|
|
up_write(&l->mutex);
|
|
kfree(l);
|
|
return;
|
|
}
|
|
mutex_unlock(&l->owner->pidlist_mutex);
|
|
up_write(&l->mutex);
|
|
}
|
|
|
|
static int cgroup_pidlist_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct cgroup_pidlist *l;
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return 0;
|
|
/*
|
|
* the seq_file will only be initialized if the file was opened for
|
|
* reading; hence we check if it's not null only in that case.
|
|
*/
|
|
l = ((struct seq_file *)file->private_data)->private;
|
|
cgroup_release_pid_array(l);
|
|
return seq_release(inode, file);
|
|
}
|
|
|
|
static const struct file_operations cgroup_pidlist_operations = {
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.write = cgroup_file_write,
|
|
.release = cgroup_pidlist_release,
|
|
};
|
|
|
|
/*
|
|
* The following functions handle opens on a file that displays a pidlist
|
|
* (tasks or procs). Prepare an array of the process/thread IDs of whoever's
|
|
* in the cgroup.
|
|
*/
|
|
/* helper function for the two below it */
|
|
static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type)
|
|
{
|
|
struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);
|
|
struct cgroup_pidlist *l;
|
|
int retval;
|
|
|
|
/* Nothing to do for write-only files */
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return 0;
|
|
|
|
/* have the array populated */
|
|
retval = pidlist_array_load(cgrp, type, &l);
|
|
if (retval)
|
|
return retval;
|
|
/* configure file information */
|
|
file->f_op = &cgroup_pidlist_operations;
|
|
|
|
retval = seq_open(file, &cgroup_pidlist_seq_operations);
|
|
if (retval) {
|
|
cgroup_release_pid_array(l);
|
|
return retval;
|
|
}
|
|
((struct seq_file *)file->private_data)->private = l;
|
|
return 0;
|
|
}
|
|
static int cgroup_tasks_open(struct inode *unused, struct file *file)
|
|
{
|
|
return cgroup_pidlist_open(file, CGROUP_FILE_TASKS);
|
|
}
|
|
static int cgroup_procs_open(struct inode *unused, struct file *file)
|
|
{
|
|
return cgroup_pidlist_open(file, CGROUP_FILE_PROCS);
|
|
}
|
|
|
|
static u64 cgroup_read_notify_on_release(struct cgroup *cgrp,
|
|
struct cftype *cft)
|
|
{
|
|
return notify_on_release(cgrp);
|
|
}
|
|
|
|
static int cgroup_write_notify_on_release(struct cgroup *cgrp,
|
|
struct cftype *cft,
|
|
u64 val)
|
|
{
|
|
clear_bit(CGRP_RELEASABLE, &cgrp->flags);
|
|
if (val)
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
else
|
|
clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* When dput() is called asynchronously, if umount has been done and
|
|
* then deactivate_super() in cgroup_free_fn() kills the superblock,
|
|
* there's a small window that vfs will see the root dentry with non-zero
|
|
* refcnt and trigger BUG().
|
|
*
|
|
* That's why we hold a reference before dput() and drop it right after.
|
|
*/
|
|
static void cgroup_dput(struct cgroup *cgrp)
|
|
{
|
|
struct super_block *sb = cgrp->root->sb;
|
|
|
|
atomic_inc(&sb->s_active);
|
|
dput(cgrp->dentry);
|
|
deactivate_super(sb);
|
|
}
|
|
|
|
/*
|
|
* Unregister event and free resources.
|
|
*
|
|
* Gets called from workqueue.
|
|
*/
|
|
static void cgroup_event_remove(struct work_struct *work)
|
|
{
|
|
struct cgroup_event *event = container_of(work, struct cgroup_event,
|
|
remove);
|
|
struct cgroup *cgrp = event->cgrp;
|
|
|
|
remove_wait_queue(event->wqh, &event->wait);
|
|
|
|
event->cft->unregister_event(cgrp, event->cft, event->eventfd);
|
|
|
|
/* Notify userspace the event is going away. */
|
|
eventfd_signal(event->eventfd, 1);
|
|
|
|
eventfd_ctx_put(event->eventfd);
|
|
kfree(event);
|
|
cgroup_dput(cgrp);
|
|
}
|
|
|
|
/*
|
|
* Gets called on POLLHUP on eventfd when user closes it.
|
|
*
|
|
* Called with wqh->lock held and interrupts disabled.
|
|
*/
|
|
static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
|
|
int sync, void *key)
|
|
{
|
|
struct cgroup_event *event = container_of(wait,
|
|
struct cgroup_event, wait);
|
|
struct cgroup *cgrp = event->cgrp;
|
|
unsigned long flags = (unsigned long)key;
|
|
|
|
if (flags & POLLHUP) {
|
|
/*
|
|
* If the event has been detached at cgroup removal, we
|
|
* can simply return knowing the other side will cleanup
|
|
* for us.
|
|
*
|
|
* We can't race against event freeing since the other
|
|
* side will require wqh->lock via remove_wait_queue(),
|
|
* which we hold.
|
|
*/
|
|
spin_lock(&cgrp->event_list_lock);
|
|
if (!list_empty(&event->list)) {
|
|
list_del_init(&event->list);
|
|
/*
|
|
* We are in atomic context, but cgroup_event_remove()
|
|
* may sleep, so we have to call it in workqueue.
|
|
*/
|
|
schedule_work(&event->remove);
|
|
}
|
|
spin_unlock(&cgrp->event_list_lock);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void cgroup_event_ptable_queue_proc(struct file *file,
|
|
wait_queue_head_t *wqh, poll_table *pt)
|
|
{
|
|
struct cgroup_event *event = container_of(pt,
|
|
struct cgroup_event, pt);
|
|
|
|
event->wqh = wqh;
|
|
add_wait_queue(wqh, &event->wait);
|
|
}
|
|
|
|
/*
|
|
* Parse input and register new cgroup event handler.
|
|
*
|
|
* Input must be in format '<event_fd> <control_fd> <args>'.
|
|
* Interpretation of args is defined by control file implementation.
|
|
*/
|
|
static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
|
|
const char *buffer)
|
|
{
|
|
struct cgroup_event *event = NULL;
|
|
struct cgroup *cgrp_cfile;
|
|
unsigned int efd, cfd;
|
|
struct file *efile = NULL;
|
|
struct file *cfile = NULL;
|
|
char *endp;
|
|
int ret;
|
|
|
|
efd = simple_strtoul(buffer, &endp, 10);
|
|
if (*endp != ' ')
|
|
return -EINVAL;
|
|
buffer = endp + 1;
|
|
|
|
cfd = simple_strtoul(buffer, &endp, 10);
|
|
if ((*endp != ' ') && (*endp != '\0'))
|
|
return -EINVAL;
|
|
buffer = endp + 1;
|
|
|
|
event = kzalloc(sizeof(*event), GFP_KERNEL);
|
|
if (!event)
|
|
return -ENOMEM;
|
|
event->cgrp = cgrp;
|
|
INIT_LIST_HEAD(&event->list);
|
|
init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc);
|
|
init_waitqueue_func_entry(&event->wait, cgroup_event_wake);
|
|
INIT_WORK(&event->remove, cgroup_event_remove);
|
|
|
|
efile = eventfd_fget(efd);
|
|
if (IS_ERR(efile)) {
|
|
ret = PTR_ERR(efile);
|
|
goto fail;
|
|
}
|
|
|
|
event->eventfd = eventfd_ctx_fileget(efile);
|
|
if (IS_ERR(event->eventfd)) {
|
|
ret = PTR_ERR(event->eventfd);
|
|
goto fail;
|
|
}
|
|
|
|
cfile = fget(cfd);
|
|
if (!cfile) {
|
|
ret = -EBADF;
|
|
goto fail;
|
|
}
|
|
|
|
/* the process need read permission on control file */
|
|
/* AV: shouldn't we check that it's been opened for read instead? */
|
|
ret = inode_permission(file_inode(cfile), MAY_READ);
|
|
if (ret < 0)
|
|
goto fail;
|
|
|
|
event->cft = __file_cft(cfile);
|
|
if (IS_ERR(event->cft)) {
|
|
ret = PTR_ERR(event->cft);
|
|
goto fail;
|
|
}
|
|
|
|
/*
|
|
* The file to be monitored must be in the same cgroup as
|
|
* cgroup.event_control is.
|
|
*/
|
|
cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);
|
|
if (cgrp_cfile != cgrp) {
|
|
ret = -EINVAL;
|
|
goto fail;
|
|
}
|
|
|
|
if (!event->cft->register_event || !event->cft->unregister_event) {
|
|
ret = -EINVAL;
|
|
goto fail;
|
|
}
|
|
|
|
ret = event->cft->register_event(cgrp, event->cft,
|
|
event->eventfd, buffer);
|
|
if (ret)
|
|
goto fail;
|
|
|
|
efile->f_op->poll(efile, &event->pt);
|
|
|
|
/*
|
|
* Events should be removed after rmdir of cgroup directory, but before
|
|
* destroying subsystem state objects. Let's take reference to cgroup
|
|
* directory dentry to do that.
|
|
*/
|
|
dget(cgrp->dentry);
|
|
|
|
spin_lock(&cgrp->event_list_lock);
|
|
list_add(&event->list, &cgrp->event_list);
|
|
spin_unlock(&cgrp->event_list_lock);
|
|
|
|
fput(cfile);
|
|
fput(efile);
|
|
|
|
return 0;
|
|
|
|
fail:
|
|
if (cfile)
|
|
fput(cfile);
|
|
|
|
if (event && event->eventfd && !IS_ERR(event->eventfd))
|
|
eventfd_ctx_put(event->eventfd);
|
|
|
|
if (!IS_ERR_OR_NULL(efile))
|
|
fput(efile);
|
|
|
|
kfree(event);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static u64 cgroup_clone_children_read(struct cgroup *cgrp,
|
|
struct cftype *cft)
|
|
{
|
|
return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
|
|
}
|
|
|
|
static int cgroup_clone_children_write(struct cgroup *cgrp,
|
|
struct cftype *cft,
|
|
u64 val)
|
|
{
|
|
if (val)
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
|
|
else
|
|
clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
|
|
return 0;
|
|
}
|
|
|
|
static struct cftype cgroup_base_files[] = {
|
|
{
|
|
.name = "cgroup.procs",
|
|
.open = cgroup_procs_open,
|
|
.write_u64 = cgroup_procs_write,
|
|
.release = cgroup_pidlist_release,
|
|
.mode = S_IRUGO | S_IWUSR,
|
|
},
|
|
{
|
|
.name = "cgroup.event_control",
|
|
.write_string = cgroup_write_event_control,
|
|
.mode = S_IWUGO,
|
|
},
|
|
{
|
|
.name = "cgroup.clone_children",
|
|
.flags = CFTYPE_INSANE,
|
|
.read_u64 = cgroup_clone_children_read,
|
|
.write_u64 = cgroup_clone_children_write,
|
|
},
|
|
{
|
|
.name = "cgroup.sane_behavior",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.read_seq_string = cgroup_sane_behavior_show,
|
|
},
|
|
|
|
/*
|
|
* Historical crazy stuff. These don't have "cgroup." prefix and
|
|
* don't exist if sane_behavior. If you're depending on these, be
|
|
* prepared to be burned.
|
|
*/
|
|
{
|
|
.name = "tasks",
|
|
.flags = CFTYPE_INSANE, /* use "procs" instead */
|
|
.open = cgroup_tasks_open,
|
|
.write_u64 = cgroup_tasks_write,
|
|
.release = cgroup_pidlist_release,
|
|
.mode = S_IRUGO | S_IWUSR,
|
|
},
|
|
{
|
|
.name = "notify_on_release",
|
|
.flags = CFTYPE_INSANE,
|
|
.read_u64 = cgroup_read_notify_on_release,
|
|
.write_u64 = cgroup_write_notify_on_release,
|
|
},
|
|
{
|
|
.name = "release_agent",
|
|
.flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
|
|
.read_seq_string = cgroup_release_agent_show,
|
|
.write_string = cgroup_release_agent_write,
|
|
.max_write_len = PATH_MAX,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/**
|
|
* cgroup_populate_dir - selectively creation of files in a directory
|
|
* @cgrp: target cgroup
|
|
* @base_files: true if the base files should be added
|
|
* @subsys_mask: mask of the subsystem ids whose files should be added
|
|
*/
|
|
static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files,
|
|
unsigned long subsys_mask)
|
|
{
|
|
int err;
|
|
struct cgroup_subsys *ss;
|
|
|
|
if (base_files) {
|
|
err = cgroup_addrm_files(cgrp, NULL, cgroup_base_files, true);
|
|
if (err < 0)
|
|
return err;
|
|
}
|
|
|
|
/* process cftsets of each subsystem */
|
|
for_each_root_subsys(cgrp->root, ss) {
|
|
struct cftype_set *set;
|
|
if (!test_bit(ss->subsys_id, &subsys_mask))
|
|
continue;
|
|
|
|
list_for_each_entry(set, &ss->cftsets, node)
|
|
cgroup_addrm_files(cgrp, ss, set->cfts, true);
|
|
}
|
|
|
|
/* This cgroup is ready now */
|
|
for_each_root_subsys(cgrp->root, ss) {
|
|
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
|
|
struct css_id *id = rcu_dereference_protected(css->id, true);
|
|
|
|
/*
|
|
* Update id->css pointer and make this css visible from
|
|
* CSS ID functions. This pointer will be dereferened
|
|
* from RCU-read-side without locks.
|
|
*/
|
|
if (id)
|
|
rcu_assign_pointer(id->css, css);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void css_dput_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(work, struct cgroup_subsys_state, dput_work);
|
|
|
|
cgroup_dput(css->cgroup);
|
|
}
|
|
|
|
static void css_release(struct percpu_ref *ref)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(ref, struct cgroup_subsys_state, refcnt);
|
|
|
|
schedule_work(&css->dput_work);
|
|
}
|
|
|
|
static void init_cgroup_css(struct cgroup_subsys_state *css,
|
|
struct cgroup_subsys *ss,
|
|
struct cgroup *cgrp)
|
|
{
|
|
css->cgroup = cgrp;
|
|
css->flags = 0;
|
|
css->id = NULL;
|
|
if (cgrp == cgroup_dummy_top)
|
|
css->flags |= CSS_ROOT;
|
|
BUG_ON(cgrp->subsys[ss->subsys_id]);
|
|
cgrp->subsys[ss->subsys_id] = css;
|
|
|
|
/*
|
|
* css holds an extra ref to @cgrp->dentry which is put on the last
|
|
* css_put(). dput() requires process context, which css_put() may
|
|
* be called without. @css->dput_work will be used to invoke
|
|
* dput() asynchronously from css_put().
|
|
*/
|
|
INIT_WORK(&css->dput_work, css_dput_fn);
|
|
}
|
|
|
|
/* invoke ->post_create() on a new CSS and mark it online if successful */
|
|
static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
|
|
{
|
|
int ret = 0;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (ss->css_online)
|
|
ret = ss->css_online(cgrp);
|
|
if (!ret)
|
|
cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE;
|
|
return ret;
|
|
}
|
|
|
|
/* if the CSS is online, invoke ->pre_destory() on it and mark it offline */
|
|
static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
|
|
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
|
|
{
|
|
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (!(css->flags & CSS_ONLINE))
|
|
return;
|
|
|
|
if (ss->css_offline)
|
|
ss->css_offline(cgrp);
|
|
|
|
cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE;
|
|
}
|
|
|
|
/*
|
|
* cgroup_create - create a cgroup
|
|
* @parent: cgroup that will be parent of the new cgroup
|
|
* @dentry: dentry of the new cgroup
|
|
* @mode: mode to set on new inode
|
|
*
|
|
* Must be called with the mutex on the parent inode held
|
|
*/
|
|
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
|
|
umode_t mode)
|
|
{
|
|
struct cgroup *cgrp;
|
|
struct cgroup_name *name;
|
|
struct cgroupfs_root *root = parent->root;
|
|
int err = 0;
|
|
struct cgroup_subsys *ss;
|
|
struct super_block *sb = root->sb;
|
|
|
|
/* allocate the cgroup and its ID, 0 is reserved for the root */
|
|
cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
|
|
if (!cgrp)
|
|
return -ENOMEM;
|
|
|
|
name = cgroup_alloc_name(dentry);
|
|
if (!name)
|
|
goto err_free_cgrp;
|
|
rcu_assign_pointer(cgrp->name, name);
|
|
|
|
cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL);
|
|
if (cgrp->id < 0)
|
|
goto err_free_name;
|
|
|
|
/*
|
|
* Only live parents can have children. Note that the liveliness
|
|
* check isn't strictly necessary because cgroup_mkdir() and
|
|
* cgroup_rmdir() are fully synchronized by i_mutex; however, do it
|
|
* anyway so that locking is contained inside cgroup proper and we
|
|
* don't get nasty surprises if we ever grow another caller.
|
|
*/
|
|
if (!cgroup_lock_live_group(parent)) {
|
|
err = -ENODEV;
|
|
goto err_free_id;
|
|
}
|
|
|
|
/* Grab a reference on the superblock so the hierarchy doesn't
|
|
* get deleted on unmount if there are child cgroups. This
|
|
* can be done outside cgroup_mutex, since the sb can't
|
|
* disappear while someone has an open control file on the
|
|
* fs */
|
|
atomic_inc(&sb->s_active);
|
|
|
|
init_cgroup_housekeeping(cgrp);
|
|
|
|
dentry->d_fsdata = cgrp;
|
|
cgrp->dentry = dentry;
|
|
|
|
cgrp->parent = parent;
|
|
cgrp->root = parent->root;
|
|
|
|
if (notify_on_release(parent))
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
|
|
|
|
for_each_root_subsys(root, ss) {
|
|
struct cgroup_subsys_state *css;
|
|
|
|
css = ss->css_alloc(cgrp);
|
|
if (IS_ERR(css)) {
|
|
err = PTR_ERR(css);
|
|
goto err_free_all;
|
|
}
|
|
|
|
err = percpu_ref_init(&css->refcnt, css_release);
|
|
if (err)
|
|
goto err_free_all;
|
|
|
|
init_cgroup_css(css, ss, cgrp);
|
|
|
|
if (ss->use_id) {
|
|
err = alloc_css_id(ss, parent, cgrp);
|
|
if (err)
|
|
goto err_free_all;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Create directory. cgroup_create_file() returns with the new
|
|
* directory locked on success so that it can be populated without
|
|
* dropping cgroup_mutex.
|
|
*/
|
|
err = cgroup_create_file(dentry, S_IFDIR | mode, sb);
|
|
if (err < 0)
|
|
goto err_free_all;
|
|
lockdep_assert_held(&dentry->d_inode->i_mutex);
|
|
|
|
cgrp->serial_nr = cgroup_serial_nr_next++;
|
|
|
|
/* allocation complete, commit to creation */
|
|
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
|
|
root->number_of_cgroups++;
|
|
|
|
/* each css holds a ref to the cgroup's dentry */
|
|
for_each_root_subsys(root, ss)
|
|
dget(dentry);
|
|
|
|
/* hold a ref to the parent's dentry */
|
|
dget(parent->dentry);
|
|
|
|
/* creation succeeded, notify subsystems */
|
|
for_each_root_subsys(root, ss) {
|
|
err = online_css(ss, cgrp);
|
|
if (err)
|
|
goto err_destroy;
|
|
|
|
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
|
|
parent->parent) {
|
|
pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
|
|
current->comm, current->pid, ss->name);
|
|
if (!strcmp(ss->name, "memory"))
|
|
pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
|
|
ss->warned_broken_hierarchy = true;
|
|
}
|
|
}
|
|
|
|
err = cgroup_populate_dir(cgrp, true, root->subsys_mask);
|
|
if (err)
|
|
goto err_destroy;
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
|
|
|
|
return 0;
|
|
|
|
err_free_all:
|
|
for_each_root_subsys(root, ss) {
|
|
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
|
|
|
|
if (css) {
|
|
percpu_ref_cancel_init(&css->refcnt);
|
|
ss->css_free(cgrp);
|
|
}
|
|
}
|
|
mutex_unlock(&cgroup_mutex);
|
|
/* Release the reference count that we took on the superblock */
|
|
deactivate_super(sb);
|
|
err_free_id:
|
|
ida_simple_remove(&root->cgroup_ida, cgrp->id);
|
|
err_free_name:
|
|
kfree(rcu_dereference_raw(cgrp->name));
|
|
err_free_cgrp:
|
|
kfree(cgrp);
|
|
return err;
|
|
|
|
err_destroy:
|
|
cgroup_destroy_locked(cgrp);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&dentry->d_inode->i_mutex);
|
|
return err;
|
|
}
|
|
|
|
static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
|
|
{
|
|
struct cgroup *c_parent = dentry->d_parent->d_fsdata;
|
|
|
|
/* the vfs holds inode->i_mutex already */
|
|
return cgroup_create(c_parent, dentry, mode | S_IFDIR);
|
|
}
|
|
|
|
static void cgroup_css_killed(struct cgroup *cgrp)
|
|
{
|
|
if (!atomic_dec_and_test(&cgrp->css_kill_cnt))
|
|
return;
|
|
|
|
/* percpu ref's of all css's are killed, kick off the next step */
|
|
INIT_WORK(&cgrp->destroy_work, cgroup_offline_fn);
|
|
schedule_work(&cgrp->destroy_work);
|
|
}
|
|
|
|
static void css_ref_killed_fn(struct percpu_ref *ref)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(ref, struct cgroup_subsys_state, refcnt);
|
|
|
|
cgroup_css_killed(css->cgroup);
|
|
}
|
|
|
|
/**
|
|
* cgroup_destroy_locked - the first stage of cgroup destruction
|
|
* @cgrp: cgroup to be destroyed
|
|
*
|
|
* css's make use of percpu refcnts whose killing latency shouldn't be
|
|
* exposed to userland and are RCU protected. Also, cgroup core needs to
|
|
* guarantee that css_tryget() won't succeed by the time ->css_offline() is
|
|
* invoked. To satisfy all the requirements, destruction is implemented in
|
|
* the following two steps.
|
|
*
|
|
* s1. Verify @cgrp can be destroyed and mark it dying. Remove all
|
|
* userland visible parts and start killing the percpu refcnts of
|
|
* css's. Set up so that the next stage will be kicked off once all
|
|
* the percpu refcnts are confirmed to be killed.
|
|
*
|
|
* s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
|
|
* rest of destruction. Once all cgroup references are gone, the
|
|
* cgroup is RCU-freed.
|
|
*
|
|
* This function implements s1. After this step, @cgrp is gone as far as
|
|
* the userland is concerned and a new cgroup with the same name may be
|
|
* created. As cgroup doesn't care about the names internally, this
|
|
* doesn't cause any problem.
|
|
*/
|
|
static int cgroup_destroy_locked(struct cgroup *cgrp)
|
|
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
|
|
{
|
|
struct dentry *d = cgrp->dentry;
|
|
struct cgroup_event *event, *tmp;
|
|
struct cgroup_subsys *ss;
|
|
bool empty;
|
|
|
|
lockdep_assert_held(&d->d_inode->i_mutex);
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/*
|
|
* css_set_lock synchronizes access to ->cset_links and prevents
|
|
* @cgrp from being removed while __put_css_set() is in progress.
|
|
*/
|
|
read_lock(&css_set_lock);
|
|
empty = list_empty(&cgrp->cset_links) && list_empty(&cgrp->children);
|
|
read_unlock(&css_set_lock);
|
|
if (!empty)
|
|
return -EBUSY;
|
|
|
|
/*
|
|
* Block new css_tryget() by killing css refcnts. cgroup core
|
|
* guarantees that, by the time ->css_offline() is invoked, no new
|
|
* css reference will be given out via css_tryget(). We can't
|
|
* simply call percpu_ref_kill() and proceed to offlining css's
|
|
* because percpu_ref_kill() doesn't guarantee that the ref is seen
|
|
* as killed on all CPUs on return.
|
|
*
|
|
* Use percpu_ref_kill_and_confirm() to get notifications as each
|
|
* css is confirmed to be seen as killed on all CPUs. The
|
|
* notification callback keeps track of the number of css's to be
|
|
* killed and schedules cgroup_offline_fn() to perform the rest of
|
|
* destruction once the percpu refs of all css's are confirmed to
|
|
* be killed.
|
|
*/
|
|
atomic_set(&cgrp->css_kill_cnt, 1);
|
|
for_each_root_subsys(cgrp->root, ss) {
|
|
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
|
|
|
|
/*
|
|
* Killing would put the base ref, but we need to keep it
|
|
* alive until after ->css_offline.
|
|
*/
|
|
percpu_ref_get(&css->refcnt);
|
|
|
|
atomic_inc(&cgrp->css_kill_cnt);
|
|
percpu_ref_kill_and_confirm(&css->refcnt, css_ref_killed_fn);
|
|
}
|
|
cgroup_css_killed(cgrp);
|
|
|
|
/*
|
|
* Mark @cgrp dead. This prevents further task migration and child
|
|
* creation by disabling cgroup_lock_live_group(). Note that
|
|
* CGRP_DEAD assertion is depended upon by cgroup_next_sibling() to
|
|
* resume iteration after dropping RCU read lock. See
|
|
* cgroup_next_sibling() for details.
|
|
*/
|
|
set_bit(CGRP_DEAD, &cgrp->flags);
|
|
|
|
/* CGRP_DEAD is set, remove from ->release_list for the last time */
|
|
raw_spin_lock(&release_list_lock);
|
|
if (!list_empty(&cgrp->release_list))
|
|
list_del_init(&cgrp->release_list);
|
|
raw_spin_unlock(&release_list_lock);
|
|
|
|
/*
|
|
* Remove @cgrp directory. The removal puts the base ref but we
|
|
* aren't quite done with @cgrp yet, so hold onto it.
|
|
*/
|
|
dget(d);
|
|
cgroup_d_remove_dir(d);
|
|
|
|
/*
|
|
* Unregister events and notify userspace.
|
|
* Notify userspace about cgroup removing only after rmdir of cgroup
|
|
* directory to avoid race between userspace and kernelspace.
|
|
*/
|
|
spin_lock(&cgrp->event_list_lock);
|
|
list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) {
|
|
list_del_init(&event->list);
|
|
schedule_work(&event->remove);
|
|
}
|
|
spin_unlock(&cgrp->event_list_lock);
|
|
|
|
return 0;
|
|
};
|
|
|
|
/**
|
|
* cgroup_offline_fn - the second step of cgroup destruction
|
|
* @work: cgroup->destroy_free_work
|
|
*
|
|
* This function is invoked from a work item for a cgroup which is being
|
|
* destroyed after the percpu refcnts of all css's are guaranteed to be
|
|
* seen as killed on all CPUs, and performs the rest of destruction. This
|
|
* is the second step of destruction described in the comment above
|
|
* cgroup_destroy_locked().
|
|
*/
|
|
static void cgroup_offline_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
|
|
struct cgroup *parent = cgrp->parent;
|
|
struct dentry *d = cgrp->dentry;
|
|
struct cgroup_subsys *ss;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/*
|
|
* css_tryget() is guaranteed to fail now. Tell subsystems to
|
|
* initate destruction.
|
|
*/
|
|
for_each_root_subsys(cgrp->root, ss)
|
|
offline_css(ss, cgrp);
|
|
|
|
/*
|
|
* Put the css refs from cgroup_destroy_locked(). Each css holds
|
|
* an extra reference to the cgroup's dentry and cgroup removal
|
|
* proceeds regardless of css refs. On the last put of each css,
|
|
* whenever that may be, the extra dentry ref is put so that dentry
|
|
* destruction happens only after all css's are released.
|
|
*/
|
|
for_each_root_subsys(cgrp->root, ss)
|
|
css_put(cgrp->subsys[ss->subsys_id]);
|
|
|
|
/* delete this cgroup from parent->children */
|
|
list_del_rcu(&cgrp->sibling);
|
|
|
|
dput(d);
|
|
|
|
set_bit(CGRP_RELEASABLE, &parent->flags);
|
|
check_for_release(parent);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
|
|
{
|
|
int ret;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
ret = cgroup_destroy_locked(dentry->d_fsdata);
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss)
|
|
{
|
|
INIT_LIST_HEAD(&ss->cftsets);
|
|
|
|
/*
|
|
* base_cftset is embedded in subsys itself, no need to worry about
|
|
* deregistration.
|
|
*/
|
|
if (ss->base_cftypes) {
|
|
ss->base_cftset.cfts = ss->base_cftypes;
|
|
list_add_tail(&ss->base_cftset.node, &ss->cftsets);
|
|
}
|
|
}
|
|
|
|
static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
|
|
printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* init base cftset */
|
|
cgroup_init_cftsets(ss);
|
|
|
|
/* Create the top cgroup state for this subsystem */
|
|
list_add(&ss->sibling, &cgroup_dummy_root.subsys_list);
|
|
ss->root = &cgroup_dummy_root;
|
|
css = ss->css_alloc(cgroup_dummy_top);
|
|
/* We don't handle early failures gracefully */
|
|
BUG_ON(IS_ERR(css));
|
|
init_cgroup_css(css, ss, cgroup_dummy_top);
|
|
|
|
/* Update the init_css_set to contain a subsys
|
|
* pointer to this state - since the subsystem is
|
|
* newly registered, all tasks and hence the
|
|
* init_css_set is in the subsystem's top cgroup. */
|
|
init_css_set.subsys[ss->subsys_id] = css;
|
|
|
|
need_forkexit_callback |= ss->fork || ss->exit;
|
|
|
|
/* At system boot, before all subsystems have been
|
|
* registered, no tasks have been forked, so we don't
|
|
* need to invoke fork callbacks here. */
|
|
BUG_ON(!list_empty(&init_task.tasks));
|
|
|
|
BUG_ON(online_css(ss, cgroup_dummy_top));
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/* this function shouldn't be used with modular subsystems, since they
|
|
* need to register a subsys_id, among other things */
|
|
BUG_ON(ss->module);
|
|
}
|
|
|
|
/**
|
|
* cgroup_load_subsys: load and register a modular subsystem at runtime
|
|
* @ss: the subsystem to load
|
|
*
|
|
* This function should be called in a modular subsystem's initcall. If the
|
|
* subsystem is built as a module, it will be assigned a new subsys_id and set
|
|
* up for use. If the subsystem is built-in anyway, work is delegated to the
|
|
* simpler cgroup_init_subsys.
|
|
*/
|
|
int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
int i, ret;
|
|
struct hlist_node *tmp;
|
|
struct css_set *cset;
|
|
unsigned long key;
|
|
|
|
/* check name and function validity */
|
|
if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
|
|
ss->css_alloc == NULL || ss->css_free == NULL)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* we don't support callbacks in modular subsystems. this check is
|
|
* before the ss->module check for consistency; a subsystem that could
|
|
* be a module should still have no callbacks even if the user isn't
|
|
* compiling it as one.
|
|
*/
|
|
if (ss->fork || ss->exit)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* an optionally modular subsystem is built-in: we want to do nothing,
|
|
* since cgroup_init_subsys will have already taken care of it.
|
|
*/
|
|
if (ss->module == NULL) {
|
|
/* a sanity check */
|
|
BUG_ON(cgroup_subsys[ss->subsys_id] != ss);
|
|
return 0;
|
|
}
|
|
|
|
/* init base cftset */
|
|
cgroup_init_cftsets(ss);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
cgroup_subsys[ss->subsys_id] = ss;
|
|
|
|
/*
|
|
* no ss->css_alloc seems to need anything important in the ss
|
|
* struct, so this can happen first (i.e. before the dummy root
|
|
* attachment).
|
|
*/
|
|
css = ss->css_alloc(cgroup_dummy_top);
|
|
if (IS_ERR(css)) {
|
|
/* failure case - need to deassign the cgroup_subsys[] slot. */
|
|
cgroup_subsys[ss->subsys_id] = NULL;
|
|
mutex_unlock(&cgroup_mutex);
|
|
return PTR_ERR(css);
|
|
}
|
|
|
|
list_add(&ss->sibling, &cgroup_dummy_root.subsys_list);
|
|
ss->root = &cgroup_dummy_root;
|
|
|
|
/* our new subsystem will be attached to the dummy hierarchy. */
|
|
init_cgroup_css(css, ss, cgroup_dummy_top);
|
|
/* init_idr must be after init_cgroup_css because it sets css->id. */
|
|
if (ss->use_id) {
|
|
ret = cgroup_init_idr(ss, css);
|
|
if (ret)
|
|
goto err_unload;
|
|
}
|
|
|
|
/*
|
|
* Now we need to entangle the css into the existing css_sets. unlike
|
|
* in cgroup_init_subsys, there are now multiple css_sets, so each one
|
|
* will need a new pointer to it; done by iterating the css_set_table.
|
|
* furthermore, modifying the existing css_sets will corrupt the hash
|
|
* table state, so each changed css_set will need its hash recomputed.
|
|
* this is all done under the css_set_lock.
|
|
*/
|
|
write_lock(&css_set_lock);
|
|
hash_for_each_safe(css_set_table, i, tmp, cset, hlist) {
|
|
/* skip entries that we already rehashed */
|
|
if (cset->subsys[ss->subsys_id])
|
|
continue;
|
|
/* remove existing entry */
|
|
hash_del(&cset->hlist);
|
|
/* set new value */
|
|
cset->subsys[ss->subsys_id] = css;
|
|
/* recompute hash and restore entry */
|
|
key = css_set_hash(cset->subsys);
|
|
hash_add(css_set_table, &cset->hlist, key);
|
|
}
|
|
write_unlock(&css_set_lock);
|
|
|
|
ret = online_css(ss, cgroup_dummy_top);
|
|
if (ret)
|
|
goto err_unload;
|
|
|
|
/* success! */
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
|
|
err_unload:
|
|
mutex_unlock(&cgroup_mutex);
|
|
/* @ss can't be mounted here as try_module_get() would fail */
|
|
cgroup_unload_subsys(ss);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_load_subsys);
|
|
|
|
/**
|
|
* cgroup_unload_subsys: unload a modular subsystem
|
|
* @ss: the subsystem to unload
|
|
*
|
|
* This function should be called in a modular subsystem's exitcall. When this
|
|
* function is invoked, the refcount on the subsystem's module will be 0, so
|
|
* the subsystem will not be attached to any hierarchy.
|
|
*/
|
|
void cgroup_unload_subsys(struct cgroup_subsys *ss)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
|
|
BUG_ON(ss->module == NULL);
|
|
|
|
/*
|
|
* we shouldn't be called if the subsystem is in use, and the use of
|
|
* try_module_get in parse_cgroupfs_options should ensure that it
|
|
* doesn't start being used while we're killing it off.
|
|
*/
|
|
BUG_ON(ss->root != &cgroup_dummy_root);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
offline_css(ss, cgroup_dummy_top);
|
|
|
|
if (ss->use_id)
|
|
idr_destroy(&ss->idr);
|
|
|
|
/* deassign the subsys_id */
|
|
cgroup_subsys[ss->subsys_id] = NULL;
|
|
|
|
/* remove subsystem from the dummy root's list of subsystems */
|
|
list_del_init(&ss->sibling);
|
|
|
|
/*
|
|
* disentangle the css from all css_sets attached to the dummy
|
|
* top. as in loading, we need to pay our respects to the hashtable
|
|
* gods.
|
|
*/
|
|
write_lock(&css_set_lock);
|
|
list_for_each_entry(link, &cgroup_dummy_top->cset_links, cset_link) {
|
|
struct css_set *cset = link->cset;
|
|
unsigned long key;
|
|
|
|
hash_del(&cset->hlist);
|
|
cset->subsys[ss->subsys_id] = NULL;
|
|
key = css_set_hash(cset->subsys);
|
|
hash_add(css_set_table, &cset->hlist, key);
|
|
}
|
|
write_unlock(&css_set_lock);
|
|
|
|
/*
|
|
* remove subsystem's css from the cgroup_dummy_top and free it -
|
|
* need to free before marking as null because ss->css_free needs
|
|
* the cgrp->subsys pointer to find their state. note that this
|
|
* also takes care of freeing the css_id.
|
|
*/
|
|
ss->css_free(cgroup_dummy_top);
|
|
cgroup_dummy_top->subsys[ss->subsys_id] = NULL;
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_unload_subsys);
|
|
|
|
/**
|
|
* cgroup_init_early - cgroup initialization at system boot
|
|
*
|
|
* Initialize cgroups at system boot, and initialize any
|
|
* subsystems that request early init.
|
|
*/
|
|
int __init cgroup_init_early(void)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
atomic_set(&init_css_set.refcount, 1);
|
|
INIT_LIST_HEAD(&init_css_set.cgrp_links);
|
|
INIT_LIST_HEAD(&init_css_set.tasks);
|
|
INIT_HLIST_NODE(&init_css_set.hlist);
|
|
css_set_count = 1;
|
|
init_cgroup_root(&cgroup_dummy_root);
|
|
cgroup_root_count = 1;
|
|
RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
|
|
|
|
init_cgrp_cset_link.cset = &init_css_set;
|
|
init_cgrp_cset_link.cgrp = cgroup_dummy_top;
|
|
list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links);
|
|
list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links);
|
|
|
|
/* at bootup time, we don't worry about modular subsystems */
|
|
for_each_builtin_subsys(ss, i) {
|
|
BUG_ON(!ss->name);
|
|
BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
|
|
BUG_ON(!ss->css_alloc);
|
|
BUG_ON(!ss->css_free);
|
|
if (ss->subsys_id != i) {
|
|
printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
|
|
ss->name, ss->subsys_id);
|
|
BUG();
|
|
}
|
|
|
|
if (ss->early_init)
|
|
cgroup_init_subsys(ss);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_init - cgroup initialization
|
|
*
|
|
* Register cgroup filesystem and /proc file, and initialize
|
|
* any subsystems that didn't request early init.
|
|
*/
|
|
int __init cgroup_init(void)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
unsigned long key;
|
|
int i, err;
|
|
|
|
err = bdi_init(&cgroup_backing_dev_info);
|
|
if (err)
|
|
return err;
|
|
|
|
for_each_builtin_subsys(ss, i) {
|
|
if (!ss->early_init)
|
|
cgroup_init_subsys(ss);
|
|
if (ss->use_id)
|
|
cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]);
|
|
}
|
|
|
|
/* allocate id for the dummy hierarchy */
|
|
mutex_lock(&cgroup_mutex);
|
|
mutex_lock(&cgroup_root_mutex);
|
|
|
|
/* Add init_css_set to the hash table */
|
|
key = css_set_hash(init_css_set.subsys);
|
|
hash_add(css_set_table, &init_css_set.hlist, key);
|
|
|
|
BUG_ON(cgroup_init_root_id(&cgroup_dummy_root, 0, 1));
|
|
|
|
mutex_unlock(&cgroup_root_mutex);
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
|
|
if (!cgroup_kobj) {
|
|
err = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
err = register_filesystem(&cgroup_fs_type);
|
|
if (err < 0) {
|
|
kobject_put(cgroup_kobj);
|
|
goto out;
|
|
}
|
|
|
|
proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
|
|
|
|
out:
|
|
if (err)
|
|
bdi_destroy(&cgroup_backing_dev_info);
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* proc_cgroup_show()
|
|
* - Print task's cgroup paths into seq_file, one line for each hierarchy
|
|
* - Used for /proc/<pid>/cgroup.
|
|
* - No need to task_lock(tsk) on this tsk->cgroup reference, as it
|
|
* doesn't really matter if tsk->cgroup changes after we read it,
|
|
* and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
|
|
* anyway. No need to check that tsk->cgroup != NULL, thanks to
|
|
* the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
|
|
* cgroup to top_cgroup.
|
|
*/
|
|
|
|
/* TODO: Use a proper seq_file iterator */
|
|
int proc_cgroup_show(struct seq_file *m, void *v)
|
|
{
|
|
struct pid *pid;
|
|
struct task_struct *tsk;
|
|
char *buf;
|
|
int retval;
|
|
struct cgroupfs_root *root;
|
|
|
|
retval = -ENOMEM;
|
|
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!buf)
|
|
goto out;
|
|
|
|
retval = -ESRCH;
|
|
pid = m->private;
|
|
tsk = get_pid_task(pid, PIDTYPE_PID);
|
|
if (!tsk)
|
|
goto out_free;
|
|
|
|
retval = 0;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
for_each_active_root(root) {
|
|
struct cgroup_subsys *ss;
|
|
struct cgroup *cgrp;
|
|
int count = 0;
|
|
|
|
seq_printf(m, "%d:", root->hierarchy_id);
|
|
for_each_root_subsys(root, ss)
|
|
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
|
|
if (strlen(root->name))
|
|
seq_printf(m, "%sname=%s", count ? "," : "",
|
|
root->name);
|
|
seq_putc(m, ':');
|
|
cgrp = task_cgroup_from_root(tsk, root);
|
|
retval = cgroup_path(cgrp, buf, PAGE_SIZE);
|
|
if (retval < 0)
|
|
goto out_unlock;
|
|
seq_puts(m, buf);
|
|
seq_putc(m, '\n');
|
|
}
|
|
|
|
out_unlock:
|
|
mutex_unlock(&cgroup_mutex);
|
|
put_task_struct(tsk);
|
|
out_free:
|
|
kfree(buf);
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
/* Display information about each subsystem and each hierarchy */
|
|
static int proc_cgroupstats_show(struct seq_file *m, void *v)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
|
|
/*
|
|
* ideally we don't want subsystems moving around while we do this.
|
|
* cgroup_mutex is also necessary to guarantee an atomic snapshot of
|
|
* subsys/hierarchy state.
|
|
*/
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
for_each_subsys(ss, i)
|
|
seq_printf(m, "%s\t%d\t%d\t%d\n",
|
|
ss->name, ss->root->hierarchy_id,
|
|
ss->root->number_of_cgroups, !ss->disabled);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroupstats_open(struct inode *inode, struct file *file)
|
|
{
|
|
return single_open(file, proc_cgroupstats_show, NULL);
|
|
}
|
|
|
|
static const struct file_operations proc_cgroupstats_operations = {
|
|
.open = cgroupstats_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
/**
|
|
* cgroup_fork - attach newly forked task to its parents cgroup.
|
|
* @child: pointer to task_struct of forking parent process.
|
|
*
|
|
* Description: A task inherits its parent's cgroup at fork().
|
|
*
|
|
* A pointer to the shared css_set was automatically copied in
|
|
* fork.c by dup_task_struct(). However, we ignore that copy, since
|
|
* it was not made under the protection of RCU or cgroup_mutex, so
|
|
* might no longer be a valid cgroup pointer. cgroup_attach_task() might
|
|
* have already changed current->cgroups, allowing the previously
|
|
* referenced cgroup group to be removed and freed.
|
|
*
|
|
* At the point that cgroup_fork() is called, 'current' is the parent
|
|
* task, and the passed argument 'child' points to the child task.
|
|
*/
|
|
void cgroup_fork(struct task_struct *child)
|
|
{
|
|
task_lock(current);
|
|
get_css_set(task_css_set(current));
|
|
child->cgroups = current->cgroups;
|
|
task_unlock(current);
|
|
INIT_LIST_HEAD(&child->cg_list);
|
|
}
|
|
|
|
/**
|
|
* cgroup_post_fork - called on a new task after adding it to the task list
|
|
* @child: the task in question
|
|
*
|
|
* Adds the task to the list running through its css_set if necessary and
|
|
* call the subsystem fork() callbacks. Has to be after the task is
|
|
* visible on the task list in case we race with the first call to
|
|
* cgroup_iter_start() - to guarantee that the new task ends up on its
|
|
* list.
|
|
*/
|
|
void cgroup_post_fork(struct task_struct *child)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
/*
|
|
* use_task_css_set_links is set to 1 before we walk the tasklist
|
|
* under the tasklist_lock and we read it here after we added the child
|
|
* to the tasklist under the tasklist_lock as well. If the child wasn't
|
|
* yet in the tasklist when we walked through it from
|
|
* cgroup_enable_task_cg_lists(), then use_task_css_set_links value
|
|
* should be visible now due to the paired locking and barriers implied
|
|
* by LOCK/UNLOCK: it is written before the tasklist_lock unlock
|
|
* in cgroup_enable_task_cg_lists() and read here after the tasklist_lock
|
|
* lock on fork.
|
|
*/
|
|
if (use_task_css_set_links) {
|
|
write_lock(&css_set_lock);
|
|
task_lock(child);
|
|
if (list_empty(&child->cg_list))
|
|
list_add(&child->cg_list, &task_css_set(child)->tasks);
|
|
task_unlock(child);
|
|
write_unlock(&css_set_lock);
|
|
}
|
|
|
|
/*
|
|
* Call ss->fork(). This must happen after @child is linked on
|
|
* css_set; otherwise, @child might change state between ->fork()
|
|
* and addition to css_set.
|
|
*/
|
|
if (need_forkexit_callback) {
|
|
/*
|
|
* fork/exit callbacks are supported only for builtin
|
|
* subsystems, and the builtin section of the subsys
|
|
* array is immutable, so we don't need to lock the
|
|
* subsys array here. On the other hand, modular section
|
|
* of the array can be freed at module unload, so we
|
|
* can't touch that.
|
|
*/
|
|
for_each_builtin_subsys(ss, i)
|
|
if (ss->fork)
|
|
ss->fork(child);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* cgroup_exit - detach cgroup from exiting task
|
|
* @tsk: pointer to task_struct of exiting process
|
|
* @run_callback: run exit callbacks?
|
|
*
|
|
* Description: Detach cgroup from @tsk and release it.
|
|
*
|
|
* Note that cgroups marked notify_on_release force every task in
|
|
* them to take the global cgroup_mutex mutex when exiting.
|
|
* This could impact scaling on very large systems. Be reluctant to
|
|
* use notify_on_release cgroups where very high task exit scaling
|
|
* is required on large systems.
|
|
*
|
|
* the_top_cgroup_hack:
|
|
*
|
|
* Set the exiting tasks cgroup to the root cgroup (top_cgroup).
|
|
*
|
|
* We call cgroup_exit() while the task is still competent to
|
|
* handle notify_on_release(), then leave the task attached to the
|
|
* root cgroup in each hierarchy for the remainder of its exit.
|
|
*
|
|
* To do this properly, we would increment the reference count on
|
|
* top_cgroup, and near the very end of the kernel/exit.c do_exit()
|
|
* code we would add a second cgroup function call, to drop that
|
|
* reference. This would just create an unnecessary hot spot on
|
|
* the top_cgroup reference count, to no avail.
|
|
*
|
|
* Normally, holding a reference to a cgroup without bumping its
|
|
* count is unsafe. The cgroup could go away, or someone could
|
|
* attach us to a different cgroup, decrementing the count on
|
|
* the first cgroup that we never incremented. But in this case,
|
|
* top_cgroup isn't going away, and either task has PF_EXITING set,
|
|
* which wards off any cgroup_attach_task() attempts, or task is a failed
|
|
* fork, never visible to cgroup_attach_task.
|
|
*/
|
|
void cgroup_exit(struct task_struct *tsk, int run_callbacks)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
struct css_set *cset;
|
|
int i;
|
|
|
|
/*
|
|
* Unlink from the css_set task list if necessary.
|
|
* Optimistically check cg_list before taking
|
|
* css_set_lock
|
|
*/
|
|
if (!list_empty(&tsk->cg_list)) {
|
|
write_lock(&css_set_lock);
|
|
if (!list_empty(&tsk->cg_list))
|
|
list_del_init(&tsk->cg_list);
|
|
write_unlock(&css_set_lock);
|
|
}
|
|
|
|
/* Reassign the task to the init_css_set. */
|
|
task_lock(tsk);
|
|
cset = task_css_set(tsk);
|
|
RCU_INIT_POINTER(tsk->cgroups, &init_css_set);
|
|
|
|
if (run_callbacks && need_forkexit_callback) {
|
|
/*
|
|
* fork/exit callbacks are supported only for builtin
|
|
* subsystems, see cgroup_post_fork() for details.
|
|
*/
|
|
for_each_builtin_subsys(ss, i) {
|
|
if (ss->exit) {
|
|
struct cgroup *old_cgrp = cset->subsys[i]->cgroup;
|
|
struct cgroup *cgrp = task_cgroup(tsk, i);
|
|
|
|
ss->exit(cgrp, old_cgrp, tsk);
|
|
}
|
|
}
|
|
}
|
|
task_unlock(tsk);
|
|
|
|
put_css_set_taskexit(cset);
|
|
}
|
|
|
|
static void check_for_release(struct cgroup *cgrp)
|
|
{
|
|
if (cgroup_is_releasable(cgrp) &&
|
|
list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) {
|
|
/*
|
|
* Control Group is currently removeable. If it's not
|
|
* already queued for a userspace notification, queue
|
|
* it now
|
|
*/
|
|
int need_schedule_work = 0;
|
|
|
|
raw_spin_lock(&release_list_lock);
|
|
if (!cgroup_is_dead(cgrp) &&
|
|
list_empty(&cgrp->release_list)) {
|
|
list_add(&cgrp->release_list, &release_list);
|
|
need_schedule_work = 1;
|
|
}
|
|
raw_spin_unlock(&release_list_lock);
|
|
if (need_schedule_work)
|
|
schedule_work(&release_agent_work);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Notify userspace when a cgroup is released, by running the
|
|
* configured release agent with the name of the cgroup (path
|
|
* relative to the root of cgroup file system) as the argument.
|
|
*
|
|
* Most likely, this user command will try to rmdir this cgroup.
|
|
*
|
|
* This races with the possibility that some other task will be
|
|
* attached to this cgroup before it is removed, or that some other
|
|
* user task will 'mkdir' a child cgroup of this cgroup. That's ok.
|
|
* The presumed 'rmdir' will fail quietly if this cgroup is no longer
|
|
* unused, and this cgroup will be reprieved from its death sentence,
|
|
* to continue to serve a useful existence. Next time it's released,
|
|
* we will get notified again, if it still has 'notify_on_release' set.
|
|
*
|
|
* The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
|
|
* means only wait until the task is successfully execve()'d. The
|
|
* separate release agent task is forked by call_usermodehelper(),
|
|
* then control in this thread returns here, without waiting for the
|
|
* release agent task. We don't bother to wait because the caller of
|
|
* this routine has no use for the exit status of the release agent
|
|
* task, so no sense holding our caller up for that.
|
|
*/
|
|
static void cgroup_release_agent(struct work_struct *work)
|
|
{
|
|
BUG_ON(work != &release_agent_work);
|
|
mutex_lock(&cgroup_mutex);
|
|
raw_spin_lock(&release_list_lock);
|
|
while (!list_empty(&release_list)) {
|
|
char *argv[3], *envp[3];
|
|
int i;
|
|
char *pathbuf = NULL, *agentbuf = NULL;
|
|
struct cgroup *cgrp = list_entry(release_list.next,
|
|
struct cgroup,
|
|
release_list);
|
|
list_del_init(&cgrp->release_list);
|
|
raw_spin_unlock(&release_list_lock);
|
|
pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!pathbuf)
|
|
goto continue_free;
|
|
if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0)
|
|
goto continue_free;
|
|
agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
|
|
if (!agentbuf)
|
|
goto continue_free;
|
|
|
|
i = 0;
|
|
argv[i++] = agentbuf;
|
|
argv[i++] = pathbuf;
|
|
argv[i] = NULL;
|
|
|
|
i = 0;
|
|
/* minimal command environment */
|
|
envp[i++] = "HOME=/";
|
|
envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
|
|
envp[i] = NULL;
|
|
|
|
/* Drop the lock while we invoke the usermode helper,
|
|
* since the exec could involve hitting disk and hence
|
|
* be a slow process */
|
|
mutex_unlock(&cgroup_mutex);
|
|
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
|
|
mutex_lock(&cgroup_mutex);
|
|
continue_free:
|
|
kfree(pathbuf);
|
|
kfree(agentbuf);
|
|
raw_spin_lock(&release_list_lock);
|
|
}
|
|
raw_spin_unlock(&release_list_lock);
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
static int __init cgroup_disable(char *str)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
char *token;
|
|
int i;
|
|
|
|
while ((token = strsep(&str, ",")) != NULL) {
|
|
if (!*token)
|
|
continue;
|
|
|
|
/*
|
|
* cgroup_disable, being at boot time, can't know about
|
|
* module subsystems, so we don't worry about them.
|
|
*/
|
|
for_each_builtin_subsys(ss, i) {
|
|
if (!strcmp(token, ss->name)) {
|
|
ss->disabled = 1;
|
|
printk(KERN_INFO "Disabling %s control group"
|
|
" subsystem\n", ss->name);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
__setup("cgroup_disable=", cgroup_disable);
|
|
|
|
/*
|
|
* Functons for CSS ID.
|
|
*/
|
|
|
|
/* to get ID other than 0, this should be called when !cgroup_is_dead() */
|
|
unsigned short css_id(struct cgroup_subsys_state *css)
|
|
{
|
|
struct css_id *cssid;
|
|
|
|
/*
|
|
* This css_id() can return correct value when somone has refcnt
|
|
* on this or this is under rcu_read_lock(). Once css->id is allocated,
|
|
* it's unchanged until freed.
|
|
*/
|
|
cssid = rcu_dereference_raw(css->id);
|
|
|
|
if (cssid)
|
|
return cssid->id;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(css_id);
|
|
|
|
/**
|
|
* css_is_ancestor - test "root" css is an ancestor of "child"
|
|
* @child: the css to be tested.
|
|
* @root: the css supporsed to be an ancestor of the child.
|
|
*
|
|
* Returns true if "root" is an ancestor of "child" in its hierarchy. Because
|
|
* this function reads css->id, the caller must hold rcu_read_lock().
|
|
* But, considering usual usage, the csses should be valid objects after test.
|
|
* Assuming that the caller will do some action to the child if this returns
|
|
* returns true, the caller must take "child";s reference count.
|
|
* If "child" is valid object and this returns true, "root" is valid, too.
|
|
*/
|
|
|
|
bool css_is_ancestor(struct cgroup_subsys_state *child,
|
|
const struct cgroup_subsys_state *root)
|
|
{
|
|
struct css_id *child_id;
|
|
struct css_id *root_id;
|
|
|
|
child_id = rcu_dereference(child->id);
|
|
if (!child_id)
|
|
return false;
|
|
root_id = rcu_dereference(root->id);
|
|
if (!root_id)
|
|
return false;
|
|
if (child_id->depth < root_id->depth)
|
|
return false;
|
|
if (child_id->stack[root_id->depth] != root_id->id)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css)
|
|
{
|
|
struct css_id *id = rcu_dereference_protected(css->id, true);
|
|
|
|
/* When this is called before css_id initialization, id can be NULL */
|
|
if (!id)
|
|
return;
|
|
|
|
BUG_ON(!ss->use_id);
|
|
|
|
rcu_assign_pointer(id->css, NULL);
|
|
rcu_assign_pointer(css->id, NULL);
|
|
spin_lock(&ss->id_lock);
|
|
idr_remove(&ss->idr, id->id);
|
|
spin_unlock(&ss->id_lock);
|
|
kfree_rcu(id, rcu_head);
|
|
}
|
|
EXPORT_SYMBOL_GPL(free_css_id);
|
|
|
|
/*
|
|
* This is called by init or create(). Then, calls to this function are
|
|
* always serialized (By cgroup_mutex() at create()).
|
|
*/
|
|
|
|
static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
|
|
{
|
|
struct css_id *newid;
|
|
int ret, size;
|
|
|
|
BUG_ON(!ss->use_id);
|
|
|
|
size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1);
|
|
newid = kzalloc(size, GFP_KERNEL);
|
|
if (!newid)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
idr_preload(GFP_KERNEL);
|
|
spin_lock(&ss->id_lock);
|
|
/* Don't use 0. allocates an ID of 1-65535 */
|
|
ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT);
|
|
spin_unlock(&ss->id_lock);
|
|
idr_preload_end();
|
|
|
|
/* Returns error when there are no free spaces for new ID.*/
|
|
if (ret < 0)
|
|
goto err_out;
|
|
|
|
newid->id = ret;
|
|
newid->depth = depth;
|
|
return newid;
|
|
err_out:
|
|
kfree(newid);
|
|
return ERR_PTR(ret);
|
|
|
|
}
|
|
|
|
static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss,
|
|
struct cgroup_subsys_state *rootcss)
|
|
{
|
|
struct css_id *newid;
|
|
|
|
spin_lock_init(&ss->id_lock);
|
|
idr_init(&ss->idr);
|
|
|
|
newid = get_new_cssid(ss, 0);
|
|
if (IS_ERR(newid))
|
|
return PTR_ERR(newid);
|
|
|
|
newid->stack[0] = newid->id;
|
|
RCU_INIT_POINTER(newid->css, rootcss);
|
|
RCU_INIT_POINTER(rootcss->id, newid);
|
|
return 0;
|
|
}
|
|
|
|
static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
|
|
struct cgroup *child)
|
|
{
|
|
int subsys_id, i, depth = 0;
|
|
struct cgroup_subsys_state *parent_css, *child_css;
|
|
struct css_id *child_id, *parent_id;
|
|
|
|
subsys_id = ss->subsys_id;
|
|
parent_css = parent->subsys[subsys_id];
|
|
child_css = child->subsys[subsys_id];
|
|
parent_id = rcu_dereference_protected(parent_css->id, true);
|
|
depth = parent_id->depth + 1;
|
|
|
|
child_id = get_new_cssid(ss, depth);
|
|
if (IS_ERR(child_id))
|
|
return PTR_ERR(child_id);
|
|
|
|
for (i = 0; i < depth; i++)
|
|
child_id->stack[i] = parent_id->stack[i];
|
|
child_id->stack[depth] = child_id->id;
|
|
/*
|
|
* child_id->css pointer will be set after this cgroup is available
|
|
* see cgroup_populate_dir()
|
|
*/
|
|
rcu_assign_pointer(child_css->id, child_id);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* css_lookup - lookup css by id
|
|
* @ss: cgroup subsys to be looked into.
|
|
* @id: the id
|
|
*
|
|
* Returns pointer to cgroup_subsys_state if there is valid one with id.
|
|
* NULL if not. Should be called under rcu_read_lock()
|
|
*/
|
|
struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id)
|
|
{
|
|
struct css_id *cssid = NULL;
|
|
|
|
BUG_ON(!ss->use_id);
|
|
cssid = idr_find(&ss->idr, id);
|
|
|
|
if (unlikely(!cssid))
|
|
return NULL;
|
|
|
|
return rcu_dereference(cssid->css);
|
|
}
|
|
EXPORT_SYMBOL_GPL(css_lookup);
|
|
|
|
/*
|
|
* get corresponding css from file open on cgroupfs directory
|
|
*/
|
|
struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id)
|
|
{
|
|
struct cgroup *cgrp;
|
|
struct inode *inode;
|
|
struct cgroup_subsys_state *css;
|
|
|
|
inode = file_inode(f);
|
|
/* check in cgroup filesystem dir */
|
|
if (inode->i_op != &cgroup_dir_inode_operations)
|
|
return ERR_PTR(-EBADF);
|
|
|
|
if (id < 0 || id >= CGROUP_SUBSYS_COUNT)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/* get cgroup */
|
|
cgrp = __d_cgrp(f->f_dentry);
|
|
css = cgrp->subsys[id];
|
|
return css ? css : ERR_PTR(-ENOENT);
|
|
}
|
|
|
|
#ifdef CONFIG_CGROUP_DEBUG
|
|
static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
|
|
|
|
if (!css)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
return css;
|
|
}
|
|
|
|
static void debug_css_free(struct cgroup *cgrp)
|
|
{
|
|
kfree(cgrp->subsys[debug_subsys_id]);
|
|
}
|
|
|
|
static u64 debug_taskcount_read(struct cgroup *cgrp, struct cftype *cft)
|
|
{
|
|
return cgroup_task_count(cgrp);
|
|
}
|
|
|
|
static u64 current_css_set_read(struct cgroup *cgrp, struct cftype *cft)
|
|
{
|
|
return (u64)(unsigned long)current->cgroups;
|
|
}
|
|
|
|
static u64 current_css_set_refcount_read(struct cgroup *cgrp,
|
|
struct cftype *cft)
|
|
{
|
|
u64 count;
|
|
|
|
rcu_read_lock();
|
|
count = atomic_read(&task_css_set(current)->refcount);
|
|
rcu_read_unlock();
|
|
return count;
|
|
}
|
|
|
|
static int current_css_set_cg_links_read(struct cgroup *cgrp,
|
|
struct cftype *cft,
|
|
struct seq_file *seq)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
struct css_set *cset;
|
|
|
|
read_lock(&css_set_lock);
|
|
rcu_read_lock();
|
|
cset = rcu_dereference(current->cgroups);
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
const char *name;
|
|
|
|
if (c->dentry)
|
|
name = c->dentry->d_name.name;
|
|
else
|
|
name = "?";
|
|
seq_printf(seq, "Root %d group %s\n",
|
|
c->root->hierarchy_id, name);
|
|
}
|
|
rcu_read_unlock();
|
|
read_unlock(&css_set_lock);
|
|
return 0;
|
|
}
|
|
|
|
#define MAX_TASKS_SHOWN_PER_CSS 25
|
|
static int cgroup_css_links_read(struct cgroup *cgrp,
|
|
struct cftype *cft,
|
|
struct seq_file *seq)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
|
|
read_lock(&css_set_lock);
|
|
list_for_each_entry(link, &cgrp->cset_links, cset_link) {
|
|
struct css_set *cset = link->cset;
|
|
struct task_struct *task;
|
|
int count = 0;
|
|
seq_printf(seq, "css_set %p\n", cset);
|
|
list_for_each_entry(task, &cset->tasks, cg_list) {
|
|
if (count++ > MAX_TASKS_SHOWN_PER_CSS) {
|
|
seq_puts(seq, " ...\n");
|
|
break;
|
|
} else {
|
|
seq_printf(seq, " task %d\n",
|
|
task_pid_vnr(task));
|
|
}
|
|
}
|
|
}
|
|
read_unlock(&css_set_lock);
|
|
return 0;
|
|
}
|
|
|
|
static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
|
|
{
|
|
return test_bit(CGRP_RELEASABLE, &cgrp->flags);
|
|
}
|
|
|
|
static struct cftype debug_files[] = {
|
|
{
|
|
.name = "taskcount",
|
|
.read_u64 = debug_taskcount_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set",
|
|
.read_u64 = current_css_set_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set_refcount",
|
|
.read_u64 = current_css_set_refcount_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set_cg_links",
|
|
.read_seq_string = current_css_set_cg_links_read,
|
|
},
|
|
|
|
{
|
|
.name = "cgroup_css_links",
|
|
.read_seq_string = cgroup_css_links_read,
|
|
},
|
|
|
|
{
|
|
.name = "releasable",
|
|
.read_u64 = releasable_read,
|
|
},
|
|
|
|
{ } /* terminate */
|
|
};
|
|
|
|
struct cgroup_subsys debug_subsys = {
|
|
.name = "debug",
|
|
.css_alloc = debug_css_alloc,
|
|
.css_free = debug_css_free,
|
|
.subsys_id = debug_subsys_id,
|
|
.base_cftypes = debug_files,
|
|
};
|
|
#endif /* CONFIG_CGROUP_DEBUG */
|