a57eb940d1
Implement a small-memory-footprint uniprocessor-only implementation of preemptible RCU. This implementation uses but a single blocked-tasks list rather than the combinatorial number used per leaf rcu_node by TREE_PREEMPT_RCU, which reduces memory consumption and greatly simplifies processing. This version also takes advantage of uniprocessor execution to accelerate grace periods in the case where there are no readers. The general design is otherwise broadly similar to that of TREE_PREEMPT_RCU. This implementation is a step towards having RCU implementation driven off of the SMP and PREEMPT kernel configuration variables, which can happen once this implementation has accumulated sufficient experience. Removed ACCESS_ONCE() from __rcu_read_unlock() and added barrier() as suggested by Steve Rostedt in order to avoid the compiler-reordering issue noted by Mathieu Desnoyers (http://lkml.org/lkml/2010/8/16/183). As can be seen below, CONFIG_TINY_PREEMPT_RCU represents almost 5Kbyte savings compared to CONFIG_TREE_PREEMPT_RCU. Of course, for non-real-time workloads, CONFIG_TINY_RCU is even better. CONFIG_TREE_PREEMPT_RCU text data bss dec filename 13 0 0 13 kernel/rcupdate.o 6170 825 28 7023 kernel/rcutree.o ---- 7026 Total CONFIG_TINY_PREEMPT_RCU text data bss dec filename 13 0 0 13 kernel/rcupdate.o 2081 81 8 2170 kernel/rcutiny.o ---- 2183 Total CONFIG_TINY_RCU (non-preemptible) text data bss dec filename 13 0 0 13 kernel/rcupdate.o 719 25 0 744 kernel/rcutiny.o --- 757 Total Requested-by: Loïc Minier <loic.minier@canonical.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
195 lines
5.4 KiB
C
195 lines
5.4 KiB
C
#ifndef _LINUX__INIT_TASK_H
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#define _LINUX__INIT_TASK_H
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#include <linux/rcupdate.h>
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#include <linux/irqflags.h>
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#include <linux/utsname.h>
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#include <linux/lockdep.h>
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#include <linux/ftrace.h>
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#include <linux/ipc.h>
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#include <linux/pid_namespace.h>
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#include <linux/user_namespace.h>
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#include <linux/securebits.h>
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#include <net/net_namespace.h>
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extern struct files_struct init_files;
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extern struct fs_struct init_fs;
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#define INIT_SIGNALS(sig) { \
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.nr_threads = 1, \
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.wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\
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.shared_pending = { \
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.list = LIST_HEAD_INIT(sig.shared_pending.list), \
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.signal = {{0}}}, \
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.posix_timers = LIST_HEAD_INIT(sig.posix_timers), \
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.cpu_timers = INIT_CPU_TIMERS(sig.cpu_timers), \
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.rlim = INIT_RLIMITS, \
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.cputimer = { \
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.cputime = INIT_CPUTIME, \
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.running = 0, \
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.lock = __SPIN_LOCK_UNLOCKED(sig.cputimer.lock), \
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}, \
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}
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extern struct nsproxy init_nsproxy;
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#define INIT_SIGHAND(sighand) { \
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.count = ATOMIC_INIT(1), \
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.action = { { { .sa_handler = SIG_DFL, } }, }, \
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.siglock = __SPIN_LOCK_UNLOCKED(sighand.siglock), \
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.signalfd_wqh = __WAIT_QUEUE_HEAD_INITIALIZER(sighand.signalfd_wqh), \
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}
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extern struct group_info init_groups;
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#define INIT_STRUCT_PID { \
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.count = ATOMIC_INIT(1), \
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.tasks = { \
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{ .first = NULL }, \
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{ .first = NULL }, \
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{ .first = NULL }, \
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}, \
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.level = 0, \
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.numbers = { { \
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.nr = 0, \
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.ns = &init_pid_ns, \
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.pid_chain = { .next = NULL, .pprev = NULL }, \
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}, } \
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}
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#define INIT_PID_LINK(type) \
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{ \
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.node = { \
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.next = NULL, \
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.pprev = NULL, \
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}, \
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.pid = &init_struct_pid, \
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}
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#ifdef CONFIG_AUDITSYSCALL
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#define INIT_IDS \
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.loginuid = -1, \
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.sessionid = -1,
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#else
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#define INIT_IDS
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#endif
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/*
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* Because of the reduced scope of CAP_SETPCAP when filesystem
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* capabilities are in effect, it is safe to allow CAP_SETPCAP to
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* be available in the default configuration.
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*/
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# define CAP_INIT_BSET CAP_FULL_SET
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#ifdef CONFIG_TREE_PREEMPT_RCU
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#define INIT_TASK_RCU_TREE_PREEMPT() \
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.rcu_blocked_node = NULL,
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#else
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#define INIT_TASK_RCU_TREE_PREEMPT(tsk)
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#endif
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#ifdef CONFIG_PREEMPT_RCU
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#define INIT_TASK_RCU_PREEMPT(tsk) \
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.rcu_read_lock_nesting = 0, \
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.rcu_read_unlock_special = 0, \
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.rcu_node_entry = LIST_HEAD_INIT(tsk.rcu_node_entry), \
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INIT_TASK_RCU_TREE_PREEMPT()
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#else
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#define INIT_TASK_RCU_PREEMPT(tsk)
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#endif
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extern struct cred init_cred;
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#ifdef CONFIG_PERF_EVENTS
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# define INIT_PERF_EVENTS(tsk) \
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.perf_event_mutex = \
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__MUTEX_INITIALIZER(tsk.perf_event_mutex), \
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.perf_event_list = LIST_HEAD_INIT(tsk.perf_event_list),
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#else
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# define INIT_PERF_EVENTS(tsk)
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#endif
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/*
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* INIT_TASK is used to set up the first task table, touch at
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* your own risk!. Base=0, limit=0x1fffff (=2MB)
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*/
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#define INIT_TASK(tsk) \
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{ \
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.state = 0, \
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.stack = &init_thread_info, \
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.usage = ATOMIC_INIT(2), \
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.flags = PF_KTHREAD, \
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.lock_depth = -1, \
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.prio = MAX_PRIO-20, \
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.static_prio = MAX_PRIO-20, \
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.normal_prio = MAX_PRIO-20, \
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.policy = SCHED_NORMAL, \
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.cpus_allowed = CPU_MASK_ALL, \
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.mm = NULL, \
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.active_mm = &init_mm, \
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.se = { \
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.group_node = LIST_HEAD_INIT(tsk.se.group_node), \
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}, \
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.rt = { \
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.run_list = LIST_HEAD_INIT(tsk.rt.run_list), \
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.time_slice = HZ, \
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.nr_cpus_allowed = NR_CPUS, \
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}, \
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.tasks = LIST_HEAD_INIT(tsk.tasks), \
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.pushable_tasks = PLIST_NODE_INIT(tsk.pushable_tasks, MAX_PRIO), \
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.ptraced = LIST_HEAD_INIT(tsk.ptraced), \
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.ptrace_entry = LIST_HEAD_INIT(tsk.ptrace_entry), \
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.real_parent = &tsk, \
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.parent = &tsk, \
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.children = LIST_HEAD_INIT(tsk.children), \
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.sibling = LIST_HEAD_INIT(tsk.sibling), \
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.group_leader = &tsk, \
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RCU_INIT_POINTER(.real_cred, &init_cred), \
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RCU_INIT_POINTER(.cred, &init_cred), \
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.cred_guard_mutex = \
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__MUTEX_INITIALIZER(tsk.cred_guard_mutex), \
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.comm = "swapper", \
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.thread = INIT_THREAD, \
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.fs = &init_fs, \
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.files = &init_files, \
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.signal = &init_signals, \
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.sighand = &init_sighand, \
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.nsproxy = &init_nsproxy, \
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.pending = { \
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.list = LIST_HEAD_INIT(tsk.pending.list), \
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.signal = {{0}}}, \
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.blocked = {{0}}, \
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.alloc_lock = __SPIN_LOCK_UNLOCKED(tsk.alloc_lock), \
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.journal_info = NULL, \
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.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
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.fs_excl = ATOMIC_INIT(0), \
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.pi_lock = __RAW_SPIN_LOCK_UNLOCKED(tsk.pi_lock), \
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.timer_slack_ns = 50000, /* 50 usec default slack */ \
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.pids = { \
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[PIDTYPE_PID] = INIT_PID_LINK(PIDTYPE_PID), \
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[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID), \
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[PIDTYPE_SID] = INIT_PID_LINK(PIDTYPE_SID), \
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}, \
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.thread_group = LIST_HEAD_INIT(tsk.thread_group), \
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.dirties = INIT_PROP_LOCAL_SINGLE(dirties), \
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INIT_IDS \
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INIT_PERF_EVENTS(tsk) \
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INIT_TRACE_IRQFLAGS \
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INIT_LOCKDEP \
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INIT_FTRACE_GRAPH \
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INIT_TRACE_RECURSION \
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INIT_TASK_RCU_PREEMPT(tsk) \
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}
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#define INIT_CPU_TIMERS(cpu_timers) \
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{ \
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LIST_HEAD_INIT(cpu_timers[0]), \
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LIST_HEAD_INIT(cpu_timers[1]), \
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LIST_HEAD_INIT(cpu_timers[2]), \
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}
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/* Attach to the init_task data structure for proper alignment */
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#define __init_task_data __attribute__((__section__(".data..init_task")))
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#endif
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