On 06/25/2018 02:07 AM, Sagi Grimberg wrote: > >> Hi Christoph >> >> Thanks for your kindly response. >> >> On 06/20/2018 10:39 PM, Christoph Hellwig wrote: >>>> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c >>>> index 73a97fc..2a161f6 100644 >>>> --- a/drivers/nvme/host/pci.c >>>> +++ b/drivers/nvme/host/pci.c >>>> @@ -1203,6 +1203,7 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved) >>>> nvme_warn_reset(dev, csts); >>>> nvme_dev_disable(dev, false); >>>> nvme_reset_ctrl(&dev->ctrl); >>>> + __blk_mq_complete_request(req); >>>> return BLK_EH_DONE; >>>> } >>>> @@ -1213,6 +1214,11 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved) >>>> dev_warn(dev->ctrl.device, >>>> "I/O %d QID %d timeout, completion polled\n", >>>> req->tag, nvmeq->qid); >>>> + /* >>>> + * nvme_end_request will invoke blk_mq_complete_request, >>>> + * it will do nothing for this timed out request. >>>> + */ >>>> + __blk_mq_complete_request(req); >>> >>> And this clearly is bogus. We want to iterate over the tagetset >>> and cancel all requests, not do that manually here. >>> >>> That was the whole point of the original change. >>> >> >> For nvme-pci, we indeed have an issue that when nvme_reset_work->nvme_dev_disable returns, timeout path maybe still >> running and the nvme_dev_disable invoked by timeout path will race with the nvme_reset_work. >> However, the hole is still there right now w/o my changes, but just narrower. > > Given the amount of fixes (and fixes of fixes) we had in the timeout handler, maybe it'd be a good idea to step back and take a another look? > > Won't it be better to avoid disabling the device and return > BLK_EH_RESET_TIMER if we are not aborting in the timeout handler? > Yes, that would be an ideal status for nvme-pci. But we have to depend on the timeout handler to handle the timed out request from nvme_reset_work. Thanks Jianchao
