1 files changed, 13 insertions, 39 deletions

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index c4159bcc05d9..67a395039268 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -551,28 +551,23 @@ out_unlock:
  */
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
-static struct nested_calls poll_safewake_ncalls;
-
-static int ep_poll_wakeup_proc(void *priv, void *cookie, int call_nests)
-{
-	unsigned long flags;
-	wait_queue_head_t *wqueue = (wait_queue_head_t *)cookie;
-
-	spin_lock_irqsave_nested(&wqueue->lock, flags, call_nests + 1);
-	wake_up_locked_poll(wqueue, EPOLLIN);
-	spin_unlock_irqrestore(&wqueue->lock, flags);
-
-	return 0;
-}
+static DEFINE_PER_CPU(int, wakeup_nest);
 
 static void ep_poll_safewake(wait_queue_head_t *wq)
 {
-	int this_cpu = get_cpu();
-
-	ep_call_nested(&poll_safewake_ncalls,
-		       ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu);
+	unsigned long flags;
+	int subclass;
 
-	put_cpu();
+	local_irq_save(flags);
+	preempt_disable();
+	subclass = __this_cpu_read(wakeup_nest);
+	spin_lock_nested(&wq->lock, subclass + 1);
+	__this_cpu_inc(wakeup_nest);
+	wake_up_locked_poll(wq, POLLIN);
+	__this_cpu_dec(wakeup_nest);
+	spin_unlock(&wq->lock);
+	local_irq_restore(flags);
+	preempt_enable();
 }
 
 #else
@@ -671,7 +666,6 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
 			      void *priv, int depth, bool ep_locked)
 {
 	__poll_t res;
-	int pwake = 0;
 	struct epitem *epi, *nepi;
 	LIST_HEAD(txlist);
 
@@ -738,26 +732,11 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
 	 */
 	list_splice(&txlist, &ep->rdllist);
 	__pm_relax(ep->ws);
-
-	if (!list_empty(&ep->rdllist)) {
-		/*
-		 * Wake up (if active) both the eventpoll wait list and
-		 * the ->poll() wait list (delayed after we release the lock).
-		 */
-		if (waitqueue_active(&ep->wq))
-			wake_up(&ep->wq);
-		if (waitqueue_active(&ep->poll_wait))
-			pwake++;
-	}
 	write_unlock_irq(&ep->lock);
 
 	if (!ep_locked)
 		mutex_unlock(&ep->mtx);
 
-	/* We have to call this outside the lock */
-	if (pwake)
-		ep_poll_safewake(&ep->poll_wait);
-
 	return res;
 }
 
@@ -2370,11 +2349,6 @@ static int __init eventpoll_init(void)
 	 */
 	ep_nested_calls_init(&poll_loop_ncalls);
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	/* Initialize the structure used to perform safe poll wait head wake ups */
-	ep_nested_calls_init(&poll_safewake_ncalls);
-#endif
-
 	/*
 	 * We can have many thousands of epitems, so prevent this from
 	 * using an extra cache line on 64-bit (and smaller) CPUs