tree e1fe1512cd36f2b7a5a978f473be7dc9d05021fa
parent d7e4a2ea51c1b0ac0b2d53f5ab4a2e878b1c4aec
author Vladimir Davydov <vdavydov@parallels.com> 1429139580 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1429140916 -0700

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>