[PATCH AUTOSEL 6.1 27/28] virtio-blk: Ensure no requests in virtqueues before deleting vqs.

Sasha Levin
2024-02-13T00:23:22Z

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 3124837aa406..505026f0025c 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -1206,14 +1206,15 @@ 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 */
virtio_reset_device(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);

@@ -1231,7 +1232,7 @@ 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