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| author | Hugh Dickins <hughd@google.com> | 2012-03-21 16:34:21 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-21 17:55:01 -0700 |
| commit | ca464d69b19120a826aa2534de2511a6f542edf5 (patch) | |
| tree | 092582419a30825b8483640856483ea8ee56cf81 /kernel | |
| parent | 42aee6c495e07dba7410b863a360db6bb9ec6d66 (diff) | |
| download | lwn-ca464d69b19120a826aa2534de2511a6f542edf5.tar.gz lwn-ca464d69b19120a826aa2534de2511a6f542edf5.zip | |
memcg: let css_get_next() rely upon rcu_read_lock()
Remove lock and unlock around css_get_next()'s call to idr_get_next().
memcg iterators (only users of css_get_next) already did rcu_read_lock(),
and its comment demands that; but add a WARN_ON_ONCE to make sure of it.
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 8eb90f25bd7b..391d5e991e5f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -5033,6 +5033,8 @@ css_get_next(struct cgroup_subsys *ss, int id, return NULL; BUG_ON(!ss->use_id); + WARN_ON_ONCE(!rcu_read_lock_held()); + /* fill start point for scan */ tmpid = id; while (1) { @@ -5040,10 +5042,7 @@ css_get_next(struct cgroup_subsys *ss, int id, * scan next entry from bitmap(tree), tmpid is updated after * idr_get_next(). */ - spin_lock(&ss->id_lock); tmp = idr_get_next(&ss->idr, &tmpid); - spin_unlock(&ss->id_lock); - if (!tmp) break; if (tmp->depth >= depth && tmp->stack[depth] == rootid) { |