On Thu, Feb 13, 2020 at 8:38 PM Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > > 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. The generic solution may be to stop queue only when there is any in-flight request not completed. Checking -ENOMEM may not be enough, given -EIO can be returned from virtqueue_add() too in case of dma map failure. Thanks,
