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| author | Tejun Heo <tj@kernel.org> | 2013-04-07 09:29:51 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-04-07 09:29:51 -0700 |
| commit | 2219449a65ace0290cd9c2260ff337e326b8be8a (patch) | |
| tree | ca93a1567a9e07adec09a3384d23536dca44603f | |
| parent | 47cfcd0922454e49f4923b1e2d31a5bf199237c3 (diff) | |
| download | linux-3.10-2219449a65ace0290cd9c2260ff337e326b8be8a.tar.gz linux-3.10-2219449a65ace0290cd9c2260ff337e326b8be8a.tar.bz2 linux-3.10-2219449a65ace0290cd9c2260ff337e326b8be8a.zip | |
cgroup: remove cgroup_lock_is_held()
We don't want controllers to assume that the information is officially
available and do funky things with it.
The only user is task_subsys_state_check() which uses it to verify RCU
access context. We can move cgroup_lock_is_held() inside
CONFIG_PROVE_RCU but that doesn't add meaningful protection compared
to conditionally exposing cgroup_mutex.
Remove cgroup_lock_is_held(), export cgroup_mutex iff CONFIG_PROVE_RCU
and use lockdep_is_held() directly on the mutex in
task_subsys_state_check().
While at it, add parentheses around macro arguments in
task_subsys_state_check().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
| -rw-r--r-- | include/linux/cgroup.h | 13 | ||||
| -rw-r--r-- | kernel/cgroup.c | 20 |
2 files changed, 15 insertions, 18 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 63deb70f314..515927eebb3 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -30,7 +30,6 @@ struct css_id; extern int cgroup_init_early(void); extern int cgroup_init(void); -extern int cgroup_lock_is_held(void); extern void cgroup_fork(struct task_struct *p); extern void cgroup_post_fork(struct task_struct *p); extern void cgroup_exit(struct task_struct *p, int run_callbacks); @@ -552,10 +551,16 @@ static inline struct cgroup_subsys_state *cgroup_subsys_state( * rcu_dereference_check() conditions, such as locks used during the * cgroup_subsys::attach() methods. */ +#ifdef CONFIG_PROVE_RCU +extern struct mutex cgroup_mutex; #define task_subsys_state_check(task, subsys_id, __c) \ - rcu_dereference_check(task->cgroups->subsys[subsys_id], \ - lockdep_is_held(&task->alloc_lock) || \ - cgroup_lock_is_held() || (__c)) + rcu_dereference_check((task)->cgroups->subsys[(subsys_id)], \ + lockdep_is_held(&(task)->alloc_lock) || \ + lockdep_is_held(&cgroup_mutex) || (__c)) +#else +#define task_subsys_state_check(task, subsys_id, __c) \ + rcu_dereference((task)->cgroups->subsys[(subsys_id)]) +#endif static inline struct cgroup_subsys_state * task_subsys_state(struct task_struct *task, int subsys_id) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 1a65958c1a0..ba3e24a76da 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -83,7 +83,13 @@ * B happens only through cgroup_show_options() and using cgroup_root_mutex * breaks it. */ +#ifdef CONFIG_PROVE_RCU +DEFINE_MUTEX(cgroup_mutex); +EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for task_subsys_state_check() */ +#else static DEFINE_MUTEX(cgroup_mutex); +#endif + static DEFINE_MUTEX(cgroup_root_mutex); /* @@ -251,20 +257,6 @@ static int cgroup_destroy_locked(struct cgroup *cgrp); static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, struct cftype cfts[], bool is_add); -#ifdef CONFIG_PROVE_LOCKING -int cgroup_lock_is_held(void) -{ - return lockdep_is_held(&cgroup_mutex); -} -#else /* #ifdef CONFIG_PROVE_LOCKING */ -int cgroup_lock_is_held(void) -{ - return mutex_is_locked(&cgroup_mutex); -} -#endif /* #else #ifdef CONFIG_PROVE_LOCKING */ - -EXPORT_SYMBOL_GPL(cgroup_lock_is_held); - static int css_unbias_refcnt(int refcnt) { return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS; |