On Tue, Feb 18, 2020 at 8:35 PM Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > > On Tue, 18 Feb 2020 10:21:18 +0800 > Ming Lei <tom.leiming@xxxxxxxxx> wrote: > > > 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. > > > > I think this is a pretty close to that. The queue is stopped only on > ENOSPC, which means virtqueue is full. > > > Checking -ENOMEM may not be enough, given -EIO can be returned from > > virtqueue_add() > > too in case of dma map failure. > > I'm not checking on -ENOMEM. So the queue would not be stopped on EIO. > Maybe I'm misunderstanding something In any case, please have another > look at the diff, and if your concerns persist please help me understand. Looks I misread the patch, and this patch is fine: Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Thanks, Ming Lei
