debug cgroup: remove unneeded cgroup_lock

Since we are in cgroup write handler, so the cgrp is valid, so we don't
have to hold cgroup_mutex when calling cgroup_task_count().  One similar
example is in cgroup_tasks_open().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/cgroup_debug.c b/kernel/cgroup_debug.c
index daca6209202df4a84df7e0fc41025e33c7642131..0c92d797baa6d163853245481597f7fc03236da4 100644 (file)
--- a/kernel/cgroup_debug.c
+++ b/kernel/cgroup_debug.c
@@ -40,9 +40,7 @@ static u64 taskcount_read(struct cgroup *cont, struct cftype *cft)
 {
        u64 count;
 
-       cgroup_lock();
        count = cgroup_task_count(cont);
-       cgroup_unlock();
        return count;
 }