[PATCH 4/5] freezer cgroup: Fix an RCU warning in cgroup_freezing_or_frozen()
in [Kernel]
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From: Li Zefan on 22 Apr 2010 05:30 with CONFIG_PROVE_RCU, a warning can be triggered when we resume from suspend: .... include/linux/cgroup.h:533 invoked rcu_dereference_check() without protection! .... task_freezer() calls task_subsys_state(), which needs to be protected by rcu_read_lock or cgroup_mutex. Signed-off-by: Li Zefan <lizf(a)cn.fujitsu.com> --- kernel/cgroup_freezer.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index 5038f4c..ac76983 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -53,6 +53,7 @@ int cgroup_freezing_or_frozen(struct task_struct *task) struct freezer *freezer; enum freezer_state state; + rcu_read_lock(); task_lock(task); freezer = task_freezer(task); if (!freezer->css.cgroup->parent) @@ -60,6 +61,7 @@ int cgroup_freezing_or_frozen(struct task_struct *task) else state = freezer->state; task_unlock(task); + rcu_read_unlock(); return (state == CGROUP_FREEZING) || (state == CGROUP_FROZEN); } -- 1.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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