From 18d37fbeb3896e766ce398ce2fc2415734b8b3e4 Mon Sep 17 00:00:00 2001
From: Asias He <asias@redhat.com>
Date: Fri, 15 Jun 2012 08:45:25 +0200
Subject: [PATCH] --- yaml --- r: 311598 b: refs/heads/master c:
 458f27a9823a0841acb4ca59e0e7f33e181f85e2 h: refs/heads/master v: v3

---
 [refs]                 |  2 +-
 trunk/block/blk-core.c | 15 ++++++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index a9e4571b97a8..8cfb7263d69a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6d407cfaf5a56b3030b9e55d0f542601e173c5d2
+refs/heads/master: 458f27a9823a0841acb4ca59e0e7f33e181f85e2
diff --git a/trunk/block/blk-core.c b/trunk/block/blk-core.c
index 3c923a7aeb56..ce7fbf8d85a6 100644
--- a/trunk/block/blk-core.c
+++ b/trunk/block/blk-core.c
@@ -361,9 +361,10 @@ EXPORT_SYMBOL(blk_put_queue);
  */
 void blk_drain_queue(struct request_queue *q, bool drain_all)
 {
+	int i;
+
 	while (true) {
 		bool drain = false;
-		int i;
 
 		spin_lock_irq(q->queue_lock);
 
@@ -408,6 +409,18 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
 			break;
 		msleep(10);
 	}
+
+	/*
+	 * With queue marked dead, any woken up waiter will fail the
+	 * allocation path, so the wakeup chaining is lost and we're
+	 * left with hung waiters. We need to wake up those waiters.
+	 */
+	if (q->request_fn) {
+		spin_lock_irq(q->queue_lock);
+		for (i = 0; i < ARRAY_SIZE(q->rq.wait); i++)
+			wake_up_all(&q->rq.wait[i]);
+		spin_unlock_irq(q->queue_lock);
+	}
 }
 
 /**