From 15a4c835e4ed3e60dd68727cd1907e3dd89563f4 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sun, 4 May 2014 15:09:14 -0400 Subject: cgroup, memcg: implement css->id and convert css_from_id() to use it Until now, cgroup->id has been used to identify all the associated csses and css_from_id() takes cgroup ID and returns the matching css by looking up the cgroup and then dereferencing the css associated with it; however, now that the lifetimes of cgroup and css are separate, this is incorrect and breaks on the unified hierarchy when a controller is disabled and enabled back again before the previous instance is released. This patch adds css->id which is a subsystem-unique ID and converts css_from_id() to look up by the new css->id instead. memcg is the only user of css_from_id() and also converted to use css->id instead. For traditional hierarchies, this shouldn't make any functional difference. Signed-off-by: Tejun Heo Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Jianyu Zhan Acked-by: Li Zefan --- mm/memcontrol.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1d0b29715b73..c3f82f69ef58 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -527,7 +527,7 @@ static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg) static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg) { - return memcg->css.cgroup->id; + return memcg->css.id; } static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id) @@ -6401,7 +6401,7 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css) struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css)); - if (css->cgroup->id > MEM_CGROUP_ID_MAX) + if (css->id > MEM_CGROUP_ID_MAX) return -ENOSPC; if (!parent) -- cgit v1.2.3-70-g09d2