path: root/kernel
diff options
authorVladimir Davydov <vdavydov@parallels.com>2015-04-15 16:13:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-15 16:35:16 -0700
commitadbe427b92d18cf3f801e82e9cd664fbe31cea3c (patch)
treee1fe1512cd36f2b7a5a978f473be7dc9d05021fa /kernel
parentd7e4a2ea51c1b0ac0b2d53f5ab4a2e878b1c4aec (diff)
memcg: zap mem_cgroup_lookup()
mem_cgroup_lookup() is a wrapper around mem_cgroup_from_id(), which checks that id != 0 before issuing the function call. Today, there is no point in this additional check apart from optimization, because there is no css with id <= 0, so that css_from_id, called by mem_cgroup_from_id, will return NULL for any id <= 0. Since mem_cgroup_from_id is only called from mem_cgroup_lookup, let us zap mem_cgroup_lookup, substituting calls to it with mem_cgroup_from_id and moving the check if id > 0 to css_from_id. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a220fdb66568..59aa339a245c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5451,7 +5451,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
- return idr_find(&ss->css_idr, id);
+ return id > 0 ? idr_find(&ss->css_idr, id) : NULL;

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