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devcgroup: avoid using cgroup_lock

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There is nothing special that has to be protected by cgroup_lock,
so introduce devcgroup_mtuex for it's own use.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Li Zefan 2009-04-02 16:57:32 -07:00 committed by Linus Torvalds
parent d969fbe69e
commit b4046f00ee
1 changed files with 13 additions and 8 deletions
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21
security/device_cgroup.c
View file

@ -11,6 +11,7 @@
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#define ACC_MKNOD 1
#define ACC_READ 2
@ -21,9 +22,11 @@
#define DEV_CHAR 2
#define DEV_ALL 4 /* this represents all devices */
static DEFINE_MUTEX(devcgroup_mutex);
/*
* whitelist locking rules:
* hold cgroup_lock() for update/read.
* hold devcgroup_mutex for update/read.
* hold rcu_read_lock() for read.
*/
@ -67,7 +70,7 @@ static int devcgroup_can_attach(struct cgroup_subsys *ss,
}
/*
* called under cgroup_lock()
* called under devcgroup_mutex
*/
static int dev_whitelist_copy(struct list_head *dest, struct list_head *orig)
{
@ -92,7 +95,7 @@ static int dev_whitelist_copy(struct list_head *dest, struct list_head *orig)
/* Stupid prototype - don't bother combining existing entries */
/*
* called under cgroup_lock()
* called under devcgroup_mutex
*/
static int dev_whitelist_add(struct dev_cgroup *dev_cgroup,
struct dev_whitelist_item *wh)
@ -130,7 +133,7 @@ static void whitelist_item_free(struct rcu_head *rcu)
}
/*
* called under cgroup_lock()
* called under devcgroup_mutex
*/
static void dev_whitelist_rm(struct dev_cgroup *dev_cgroup,
struct dev_whitelist_item *wh)
@ -185,8 +188,10 @@ static struct cgroup_subsys_state *devcgroup_create(struct cgroup_subsys *ss,
list_add(&wh->list, &dev_cgroup->whitelist);
} else {
parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup);
mutex_lock(&devcgroup_mutex);
ret = dev_whitelist_copy(&dev_cgroup->whitelist,
&parent_dev_cgroup->whitelist);
mutex_unlock(&devcgroup_mutex);
if (ret) {
kfree(dev_cgroup);
return ERR_PTR(ret);
@ -273,7 +278,7 @@ static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft,
* does the access granted to dev_cgroup c contain the access
* requested in whitelist item refwh.
* return 1 if yes, 0 if no.
* call with c->lock held
* call with devcgroup_mutex held
*/
static int may_access_whitelist(struct dev_cgroup *c,
struct dev_whitelist_item *refwh)
@ -426,11 +431,11 @@ static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft,
const char *buffer)
{
int retval;
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
mutex_lock(&devcgroup_mutex);
retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp),
cft->private, buffer);
cgroup_unlock();
mutex_unlock(&devcgroup_mutex);
return retval;
}