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authorTejun Heo <tj@kernel.org>2013-04-07 09:29:51 -0700
committerTejun Heo <tj@kernel.org>2013-04-07 09:29:51 -0700
commit2219449a65ace0290cd9c2260ff337e326b8be8a (patch)
treeca93a1567a9e07adec09a3384d23536dca44603f /kernel/cgroup.c
parent47cfcd0922454e49f4923b1e2d31a5bf199237c3 (diff)
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>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c20
1 files changed, 6 insertions, 14 deletions
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);
-
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{
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