Patch "block: Fix race triggered by blk_set_queue_dying()" has been added to the 4.4-stable tree

Patch "block: Fix race triggered by blk_set_queue_dying()" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    block: Fix race triggered by blk_set_queue_dying()

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     block-fix-race-triggered-by-blk_set_queue_dying.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 1b856086813be9371929b6cc62045f9fd470f5a0 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bart.vanassche@sandisk.com>
Date: Tue, 16 Aug 2016 16:48:36 -0700
Subject: block: Fix race triggered by blk_set_queue_dying()

From: Bart Van Assche <bart.vanassche@sandisk.com>

commit 1b856086813be9371929b6cc62045f9fd470f5a0 upstream.

blk_set_queue_dying() can be called while another thread is
submitting I/O or changing queue flags, e.g. through dm_stop_queue().
Hence protect the QUEUE_FLAG_DYING flag change with locking.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 block/blk-core.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -515,7 +515,9 @@ EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
 
 void blk_set_queue_dying(struct request_queue *q)
 {
-	queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
+	spin_lock_irq(q->queue_lock);
+	queue_flag_set(QUEUE_FLAG_DYING, q);
+	spin_unlock_irq(q->queue_lock);
 
 	if (q->mq_ops)
 		blk_mq_wake_waiters(q);


Patches currently in stable-queue which might be from bart.vanassche@sandisk.com are

queue-4.4/block-fix-race-triggered-by-blk_set_queue_dying.patch