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| author | Vladimir Davydov <vdavydov@parallels.com> | 2015-04-15 16:13:00 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-15 16:35:16 -0700 |
| commit | adbe427b92d18cf3f801e82e9cd664fbe31cea3c (patch) | |
| tree | e1fe1512cd36f2b7a5a978f473be7dc9d05021fa /kernel/cgroup.c | |
| parent | d7e4a2ea51c1b0ac0b2d53f5ab4a2e878b1c4aec (diff) | |
| download | lwn-adbe427b92d18cf3f801e82e9cd664fbe31cea3c.tar.gz lwn-adbe427b92d18cf3f801e82e9cd664fbe31cea3c.zip | |
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/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 2 |
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) { WARN_ON_ONCE(!rcu_read_lock_held()); - return idr_find(&ss->css_idr, id); + return id > 0 ? idr_find(&ss->css_idr, id) : NULL; } #ifdef CONFIG_CGROUP_DEBUG |