From: Halil Pasic <[email protected]> [ Upstream commit f5f6b95c72f7f8bb46eace8c5306c752d0133daa ]
Since nobody else is going to restart our hw_queue for us, the blk_mq_start_stopped_hw_queues() is in virtblk_done() is not sufficient necessarily sufficient to ensure that the queue will get started again. In case of global resource outage (-ENOMEM because mapping failure, because of swiotlb full) our virtqueue may be empty and we can get stuck with a stopped hw_queue. Let us not stop the queue on arbitrary errors, but only on -EONSPC which indicates a full virtqueue, where the hw_queue is guaranteed to get started by virtblk_done() before when it makes sense to carry on submitting requests. Let us also remove a stale comment. Signed-off-by: Halil Pasic <[email protected]> Cc: Jens Axboe <[email protected]> Fixes: f7728002c1c7 ("virtio_ring: fix return code on DMA mapping fails") Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Michael S. Tsirkin <[email protected]> Reviewed-by: Stefan Hajnoczi <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- drivers/block/virtio_blk.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 7ffd719d89def..c2ed3e9128e3a 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -339,10 +339,12 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num); if (err) { virtqueue_kick(vblk->vqs[qid].vq); - blk_mq_stop_hw_queue(hctx); + /* Don't stop the queue if -ENOMEM: we may have failed to + * bounce the buffer due to global resource outage. + */ + if (err == -ENOSPC) + blk_mq_stop_hw_queue(hctx); spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags); - /* Out of mem doesn't actually happen, since we fall back - * to direct descriptors */ if (err == -ENOMEM || err == -ENOSPC) return BLK_STS_DEV_RESOURCE; return BLK_STS_IOERR; -- 2.20.1 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
