[PATCH 4.19 24/52] virtio-blk: Ensure no requests in virtqueues before deleting vqs.

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yi Sun <yi.sun@unisoc.com>

[ Upstream commit 4ce6e2db00de8103a0687fb0f65fd17124a51aaa ]

Ensure no remaining requests in virtqueues before resetting vdev and
deleting virtqueues. Otherwise these requests will never be completed.
It may cause the system to become unresponsive.

Function blk_mq_quiesce_queue() can ensure that requests have become
in_flight status, but it cannot guarantee that requests have been
processed by the device. Virtqueues should never be deleted before
all requests become complete status.

Function blk_mq_freeze_queue() ensure that all requests in virtqueues
become complete status. And no requests can enter in virtqueues.

Signed-off-by: Yi Sun <yi.sun@unisoc.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://lore.kernel.org/r/20240129085250.1550594-1-yi.sun@unisoc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/virtio_blk.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 8b3bf11329ba0..8e4c431efc6cc 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -943,14 +943,15 @@ static int virtblk_freeze(struct virtio_device *vdev)
 {
 	struct virtio_blk *vblk = vdev->priv;
 
+	/* Ensure no requests in virtqueues before deleting vqs. */
+	blk_mq_freeze_queue(vblk->disk->queue);
+
 	/* Ensure we don't receive any more interrupts */
 	vdev->config->reset(vdev);
 
 	/* Make sure no work handler is accessing the device. */
 	flush_work(&vblk->config_work);
 
-	blk_mq_quiesce_queue(vblk->disk->queue);
-
 	vdev->config->del_vqs(vdev);
 	kfree(vblk->vqs);
 
@@ -968,7 +969,7 @@ static int virtblk_restore(struct virtio_device *vdev)
 
 	virtio_device_ready(vdev);
 
-	blk_mq_unquiesce_queue(vblk->disk->queue);
+	blk_mq_unfreeze_queue(vblk->disk->queue);
 	return 0;
 }
 #endif
-- 
2.43.0