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 --- include/linux/cgroup.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux/cgroup.h') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 793f70a48820..2dfabb3b749a 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -62,6 +62,12 @@ struct cgroup_subsys_state { /* the parent css */ struct cgroup_subsys_state *parent; + /* + * Subsys-unique ID. 0 is unused and root is always 1. The + * matching css can be looked up using css_from_id(). + */ + int id; + unsigned int flags; /* percpu_ref killing and RCU release */ @@ -655,6 +661,9 @@ struct cgroup_subsys { /* link to parent, protected by cgroup_lock() */ struct cgroup_root *root; + /* idr for css->id */ + struct idr css_idr; + /* * List of cftypes. Each entry is the first entry of an array * terminated by zero length name. -- cgit v1.2.3-58-ga151