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authorLai Jiangshan <laijs@cn.fujitsu.com>2008-10-18 20:28:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-20 08:52:38 -0700
commit146aa1bd0511f88ddb4e92fafa2b8aad4f2f65f3 (patch)
treed7deb46b9a38f82f109b2126317899efbbce41c2 /include
parent248736c2a57206388c86f8cdd3392ee986e84f9f (diff)
cgroups: fix probable race with put_css_set[_taskexit] and find_css_set
put_css_set_taskexit may be called when find_css_set is called on other cpu. And the race will occur: put_css_set_taskexit side find_css_set side | atomic_dec_and_test(&kref->refcount) | /* kref->refcount = 0 */ | .................................................................... | read_lock(&css_set_lock) | find_existing_css_set | get_css_set | read_unlock(&css_set_lock); .................................................................... __release_css_set | .................................................................... | /* use a released css_set */ | [put_css_set is the same. But in the current code, all put_css_set are put into cgroup mutex critical region as the same as find_css_set.] [akpm@linux-foundation.org: repair comments] [menage@google.com: eliminate race in css_set refcounting] Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Paul Menage <menage@google.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.h3
1 files changed, 1 insertions, 2 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 30934e4bfaa..7166023e07d 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -9,7 +9,6 @@
*/
#include <linux/sched.h>
-#include <linux/kref.h>
#include <linux/cpumask.h>
#include <linux/nodemask.h>
#include <linux/rcupdate.h>
@@ -149,7 +148,7 @@ struct cgroup {
struct css_set {
/* Reference count */
- struct kref ref;
+ atomic_t refcount;
/*
* List running through all cgroup groups in the same hash