1 files changed, 19 insertions, 6 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 3c923a7aeb56..93eb3e4f88ce 100644
--- a/block/blk-core.c
+++ b/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);
+        }
 }
 
 /**
@@ -467,7 +480,6 @@ void blk_cleanup_queue(struct request_queue *q)
         /* mark @q DEAD, no new request or merges will be allowed afterwards */
         mutex_lock(&q->sysfs_lock);
         queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
-
         spin_lock_irq(lock);
 
         /*
@@ -485,10 +497,6 @@ void blk_cleanup_queue(struct request_queue *q)
         queue_flag_set(QUEUE_FLAG_NOMERGES, q);
         queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
         queue_flag_set(QUEUE_FLAG_DEAD, q);
-
-        if (q->queue_lock != &q->__queue_lock)
-                q->queue_lock = &q->__queue_lock;
-
         spin_unlock_irq(lock);
         mutex_unlock(&q->sysfs_lock);
 
@@ -499,6 +507,11 @@ void blk_cleanup_queue(struct request_queue *q)
         del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
         blk_sync_queue(q);
 
+        spin_lock_irq(lock);
+        if (q->queue_lock != &q->__queue_lock)
+                q->queue_lock = &q->__queue_lock;
+        spin_unlock_irq(lock);
+
         /* @q is and will stay empty, shutdown and put */
         blk_put_queue(q);
 }