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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 /kernel/cgroup_debug.c
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 'kernel/cgroup_debug.c')
-rw-r--r--kernel/cgroup_debug.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/cgroup_debug.c b/kernel/cgroup_debug.c
index c3dc3aba4c02..daca6209202d 100644
--- a/kernel/cgroup_debug.c
+++ b/kernel/cgroup_debug.c
@@ -57,7 +57,7 @@ static u64 current_css_set_refcount_read(struct cgroup *cont,
u64 count;
rcu_read_lock();
- count = atomic_read(&current->cgroups->ref.refcount);
+ count = atomic_read(&current->cgroups->refcount);
rcu_read_unlock();
return count;
}
@@ -90,7 +90,7 @@ static struct cftype files[] = {
{
.name = "releasable",
.read_u64 = releasable_read,
- }
+ },
};
static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)