flush_workqueue(): use preempt_disable to hold off cpu hotplug
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Gautham Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 918d552..5176d51 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -419,18 +419,22 @@
* Probably keventd trying to flush its own queue. So simply run
* it by hand rather than deadlocking.
*/
- mutex_unlock(&workqueue_mutex);
+ preempt_enable();
+ /*
+ * We can still touch *cwq here because we are keventd, and
+ * hot-unplug will be waiting us to exit.
+ */
run_workqueue(cwq);
- mutex_lock(&workqueue_mutex);
+ preempt_disable();
} else {
struct wq_barrier barr;
init_wq_barrier(&barr);
__queue_work(cwq, &barr.work);
- mutex_unlock(&workqueue_mutex);
+ preempt_enable(); /* Can no longer touch *cwq */
wait_for_completion(&barr.done);
- mutex_lock(&workqueue_mutex);
+ preempt_disable();
}
}
@@ -449,7 +453,7 @@
*/
void fastcall flush_workqueue(struct workqueue_struct *wq)
{
- mutex_lock(&workqueue_mutex);
+ preempt_disable(); /* CPU hotplug */
if (is_single_threaded(wq)) {
/* Always use first cpu's area. */
flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, singlethread_cpu));
@@ -459,7 +463,7 @@
for_each_online_cpu(cpu)
flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
}
- mutex_unlock(&workqueue_mutex);
+ preempt_enable();
}
EXPORT_SYMBOL_GPL(flush_workqueue);