summaryrefslogtreecommitdiff
path: root/kernel/workqueue.c
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2013-04-01 11:23:31 -0700
committerTejun Heo <tj@kernel.org>2013-04-01 11:23:31 -0700
commitbc0caf099d9df4dd0fad24992b043b40541f4200 (patch)
treedddcccaf93af1eacd1606aadb06105e1a8f5ee11 /kernel/workqueue.c
parentb5927605478b740d73192f587e458de1632106e8 (diff)
workqueue: fix race condition in unbound workqueue free path
8864b4e59 ("workqueue: implement get/put_pwq()") implemented pwq (pool_workqueue) refcnting which frees workqueue when the last pwq goes away. It determined whether it was the last pwq by testing wq->pwqs is empty. Unfortunately, the test was done outside wq->mutex and multiple pwq release could race and try to free wq multiple times leading to oops. Test wq->pwqs emptiness while holding wq->mutex. Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r--kernel/workqueue.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 04a8b98d30ce..4d344326ae97 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3534,6 +3534,7 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
unbound_release_work);
struct workqueue_struct *wq = pwq->wq;
struct worker_pool *pool = pwq->pool;
+ bool is_last;
if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
return;
@@ -3545,6 +3546,7 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
*/
mutex_lock(&wq->mutex);
list_del_rcu(&pwq->pwqs_node);
+ is_last = list_empty(&wq->pwqs);
mutex_unlock(&wq->mutex);
put_unbound_pool(pool);
@@ -3554,7 +3556,7 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
* If we're the last pwq going away, @wq is already dead and no one
* is gonna access it anymore. Free it.
*/
- if (list_empty(&wq->pwqs))
+ if (is_last)
kfree(wq);
}