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authorPaul Menage <menage@google.com>2009-01-07 18:07:44 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-08 08:31:03 -0800
commita47295e6bc42ad35f9c15ac66f598aa24debd4e2 (patch)
treecb765e996ef35ae88e29d60796655d0d35e8cf5e /include
parente7b80bb695a5b64c92e314838e083b2f3bdf29b2 (diff)
cgroups: make cgroup_path() RCU-safe
Fix races between /proc/sched_debug by freeing cgroup objects via an RCU callback. Thus any cgroup reference obtained from an RCU-safe source will remain valid during the RCU section. Since dentries are also RCU-safe, this allows us to traverse up the tree safely. Additionally, make cgroup_path() check for a NULL cgrp->dentry to avoid trying to report a path for a partially-created cgroup. [lizf@cn.fujitsu.com: call deactive_super() in cgroup_diput()] Signed-off-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Tested-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/cgroup.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f68dfd8dd53..73d1c730c3c 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -116,7 +116,7 @@ struct cgroup {
struct list_head children; /* my children */
struct cgroup *parent; /* my parent */
- struct dentry *dentry; /* cgroup fs entry */
+ struct dentry *dentry; /* cgroup fs entry, RCU protected */
/* Private pointers for each registered subsystem */
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
@@ -145,6 +145,9 @@ struct cgroup {
int pids_use_count;
/* Length of the current tasks_pids array */
int pids_length;
+
+ /* For RCU-protected deletion */
+ struct rcu_head rcu_head;
};
/* A css_set is a structure holding pointers to a set of