Re: [PATCH V2 5/5] nvme: pci: simplify timeout handling

jianchao.wang
2018-05-02T02:23:20Z

Hi Ming

On 04/29/2018 11:41 PM, Ming Lei wrote:
> +
> static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
> {
> struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
> @@ -1197,8 +1297,7 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
> */
> if (nvme_should_reset(dev, csts)) {
> nvme_warn_reset(dev, csts);
> - nvme_dev_disable(dev, false);
> - nvme_reset_ctrl(&dev->ctrl);
> + nvme_eh_schedule(dev);
> return BLK_EH_HANDLED;
> }
>
> @@ -1224,8 +1323,8 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
> dev_warn(dev->ctrl.device,
> "I/O %d QID %d timeout, disable controller\n",
> req->tag, nvmeq->qid);
> - nvme_dev_disable(dev, false);
> nvme_req(req)->flags |= NVME_REQ_CANCELLED;
> + nvme_eh_schedule(dev);
> return BLK_EH_HANDLED;
> default:
> break;
> @@ -1240,14 +1339,12 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
> dev_warn(dev->ctrl.device,
> "I/O %d QID %d timeout, reset controller\n",
> req->tag, nvmeq->qid);
> - nvme_dev_disable(dev, false);
> - nvme_reset_ctrl(&dev->ctrl);
> -
> /*
> * Mark the request as handled, since the inline shutdown
> * forces all outstanding requests to complete.
> */
> nvme_req(req)->flags |= NVME_REQ_CANCELLED;
> + nvme_eh_schedule(dev);
> return BLK_EH_HANDLED;
> }
>
> @@ -2246,8 +2343,8 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)
> if (pci_is_enabled(pdev)) {
> u32 csts = readl(dev->bar + NVME_REG_CSTS);
>
> - if (dev->ctrl.state == NVME_CTRL_LIVE ||
> - dev->ctrl.state == NVME_CTRL_RESETTING) {
> + if (shutdown && (dev->ctrl.state == NVME_CTRL_LIVE ||
> + dev->ctrl.state == NVME_CTRL_RESETTING)) {
> nvme_start_freeze(&dev->ctrl);
> frozen = true;
> }
> @@ -2281,11 +2378,23 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)
> for (i = dev->ctrl.queue_count - 1; i >= 0; i--)
> nvme_suspend_queue(&dev->queues[i]);
>
> + /* safe to sync timeout after queues are quiesced */
> + nvme_quiesce_timeout(&dev->ctrl);
> + blk_quiesce_timeout(dev->ctrl.admin_q);
> +
> nvme_pci_disable(dev);
>
> + /*
> + * Both timeout and interrupt handler have been drained, and all
> + * in-flight requests will be canceled now.
> + */
> blk_mq_tagset_busy_iter(&dev->tagset, nvme_cancel_request, &dev->ctrl);
> blk_mq_tagset_busy_iter(&dev->admin_tagset, nvme_cancel_request, &dev->ctrl);

We need to return BLK_EH_RESET_TIMER in nvme_timeout then:
1. defer the completion. we can't unmap the io request before close the controller totally, so not BLK_EH_HANDLED.
2. nvme_cancel_request could complete it. blk_mq_complete_request is invoked by nvme_cancel_request, so not BLK_EH_NOT_HANDLED.

Thanks
Jianchao