Merge branch 'for-linus' of git://git.kernel.dk/linux-block

Pull block bits from Jens Axboe:
 "As vacation is coming up, thought I'd better get rid of my pending
  changes in my for-linus branch for this iteration.  It contains:

   - Two patches for mtip32xx.  Killing a non-compliant sysfs interface
     and moving it to debugfs, where it belongs.

   - A few patches from Asias.  Two legit bug fixes, and one killing an
     interface that is no longer in use.

   - A patch from Jan, making the annoying partition ioctl warning a bit
     less annoying, by restricting it to !CAP_SYS_RAWIO only.

   - Three bug fixes for drbd from Lars Ellenberg.

   - A fix for an old regression for umem, it hasn't really worked since
     the plugging scheme was changed in 3.0.

   - A few fixes from Tejun.

   - A splice fix from Eric Dumazet, fixing an issue with pipe
     resizing."

* 'for-linus' of git://git.kernel.dk/linux-block:
  scsi: Silence unnecessary warnings about ioctl to partition
  block: Drop dead function blk_abort_queue()
  block: Mitigate lock unbalance caused by lock switching
  block: Avoid missed wakeup in request waitqueue
  umem: fix up unplugging
  splice: fix racy pipe->buffers uses
  drbd: fix null pointer dereference with on-congestion policy when diskless
  drbd: fix list corruption by failing but already aborted reads
  drbd: fix access of unallocated pages and kernel panic
  xen/blkfront: Add WARN to deal with misbehaving backends.
  blkcg: drop local variable @q from blkg_destroy()
  mtip32xx: Create debugfs entries for troubleshooting
  mtip32xx: Remove 'registers' and 'flags' from sysfs
  blkcg: fix blkg_alloc() failure path
  block: blkcg_policy_cfq shouldn't be used if !CONFIG_CFQ_GROUP_IOSCHED
  block: fix return value on cfq_init() failure
  mtip32xx: Remove version.h header file inclusion
  xen/blkback: Copy id field when doing BLKIF_DISCARD.

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);
 }