From: Chao Leng <lengchao@huawei.com> To: Sagi Grimberg <sagi@grimberg.me>, Ming Lei <ming.lei@redhat.com> Cc: Yi Zhang <yi.zhang@redhat.com>, Jens Axboe <axboe@kernel.dk>, <linux-block@vger.kernel.org>, Keith Busch <kbusch@kernel.org>, <linux-nvme@lists.infradead.org>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH] block: re-introduce blk_mq_complete_request_sync Date: Wed, 14 Oct 2020 09:25:43 +0800 [thread overview] Message-ID: <dba6f24d-7d4f-a89e-047d-9d63837084dd@huawei.com> (raw) In-Reply-To: <0b5bfc44-d925-960d-b2a2-d0ba88b51111@grimberg.me> On 2020/10/14 6:31, Sagi Grimberg wrote: > >>>>>>> -- >>>>>>> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c >>>>>>> index 629b025685d1..46428ff0b0fc 100644 >>>>>>> --- a/drivers/nvme/host/tcp.c >>>>>>> +++ b/drivers/nvme/host/tcp.c >>>>>>> @@ -2175,7 +2175,7 @@ static void nvme_tcp_complete_timed_out(struct request *rq) >>>>>>> /* fence other contexts that may complete the command */ >>>>>>> mutex_lock(&to_tcp_ctrl(ctrl)->teardown_lock); >>>>>>> nvme_tcp_stop_queue(ctrl, nvme_tcp_queue_id(req->queue)); >>>>>>> - if (!blk_mq_request_completed(rq)) { >>>>>>> + if (blk_mq_request_started(rq) && !blk_mq_request_completed(rq)) { >>>>>>> nvme_req(rq)->status = NVME_SC_HOST_ABORTED_CMD; >>>>>>> blk_mq_complete_request_sync(rq); >>>>>>> } >>> This may just reduce the probability. The concurrency of timeout and teardown will cause the same request >>> be treated repeatly, this is not we expected. >> >> That is right, not like SCSI, NVME doesn't apply atomic request completion, so >> request may be completed/freed from both timeout & nvme_cancel_request(). >> >> .teardown_lock still may cover the race with Sagi's patch because teardown >> actually cancels requests in sync style. >> >>> In the teardown process, after quiesced queues delete the timer and cancel the timeout work maybe a better option. >> >> Seems better solution, given it is aligned with NVME PCI's reset >> handling. nvme_sync_queues() may be called in nvme_tcp_teardown_io_queues() to >> avoid this race. > > We can't call nvme_sync_queues, that flushes the timeout work that is > serializing with the teardown, it will deadlock. yes, the teardown_lock is not needed if we sync_queue. We is testing the patch with nvme over roce. > .
WARNING: multiple messages have this Message-ID (diff)
From: Chao Leng <lengchao@huawei.com> To: Sagi Grimberg <sagi@grimberg.me>, Ming Lei <ming.lei@redhat.com> Cc: Jens Axboe <axboe@kernel.dk>, Yi Zhang <yi.zhang@redhat.com>, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH] block: re-introduce blk_mq_complete_request_sync Date: Wed, 14 Oct 2020 09:25:43 +0800 [thread overview] Message-ID: <dba6f24d-7d4f-a89e-047d-9d63837084dd@huawei.com> (raw) In-Reply-To: <0b5bfc44-d925-960d-b2a2-d0ba88b51111@grimberg.me> On 2020/10/14 6:31, Sagi Grimberg wrote: > >>>>>>> -- >>>>>>> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c >>>>>>> index 629b025685d1..46428ff0b0fc 100644 >>>>>>> --- a/drivers/nvme/host/tcp.c >>>>>>> +++ b/drivers/nvme/host/tcp.c >>>>>>> @@ -2175,7 +2175,7 @@ static void nvme_tcp_complete_timed_out(struct request *rq) >>>>>>> /* fence other contexts that may complete the command */ >>>>>>> mutex_lock(&to_tcp_ctrl(ctrl)->teardown_lock); >>>>>>> nvme_tcp_stop_queue(ctrl, nvme_tcp_queue_id(req->queue)); >>>>>>> - if (!blk_mq_request_completed(rq)) { >>>>>>> + if (blk_mq_request_started(rq) && !blk_mq_request_completed(rq)) { >>>>>>> nvme_req(rq)->status = NVME_SC_HOST_ABORTED_CMD; >>>>>>> blk_mq_complete_request_sync(rq); >>>>>>> } >>> This may just reduce the probability. The concurrency of timeout and teardown will cause the same request >>> be treated repeatly, this is not we expected. >> >> That is right, not like SCSI, NVME doesn't apply atomic request completion, so >> request may be completed/freed from both timeout & nvme_cancel_request(). >> >> .teardown_lock still may cover the race with Sagi's patch because teardown >> actually cancels requests in sync style. >> >>> In the teardown process, after quiesced queues delete the timer and cancel the timeout work maybe a better option. >> >> Seems better solution, given it is aligned with NVME PCI's reset >> handling. nvme_sync_queues() may be called in nvme_tcp_teardown_io_queues() to >> avoid this race. > > We can't call nvme_sync_queues, that flushes the timeout work that is > serializing with the teardown, it will deadlock. yes, the teardown_lock is not needed if we sync_queue. We is testing the patch with nvme over roce. > . _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme
next prev parent reply other threads:[~2020-10-14 1:25 UTC|newest] Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-08 21:37 [PATCH] block: re-introduce blk_mq_complete_request_sync Sagi Grimberg 2020-10-08 21:37 ` Sagi Grimberg 2020-10-09 4:39 ` Ming Lei 2020-10-09 4:39 ` Ming Lei 2020-10-09 5:03 ` Yi Zhang 2020-10-09 5:03 ` Yi Zhang 2020-10-09 8:09 ` Sagi Grimberg 2020-10-09 8:09 ` Sagi Grimberg 2020-10-09 13:55 ` Yi Zhang 2020-10-09 13:55 ` Yi Zhang 2020-10-09 18:29 ` Sagi Grimberg 2020-10-09 18:29 ` Sagi Grimberg 2020-10-10 6:08 ` Yi Zhang 2020-10-10 6:08 ` Yi Zhang 2020-10-12 3:59 ` Chao Leng 2020-10-12 3:59 ` Chao Leng 2020-10-12 8:13 ` Ming Lei 2020-10-12 8:13 ` Ming Lei 2020-10-12 9:06 ` Chao Leng 2020-10-12 9:06 ` Chao Leng 2020-10-13 22:36 ` Sagi Grimberg 2020-10-13 22:36 ` Sagi Grimberg 2020-10-14 1:08 ` Ming Lei 2020-10-14 1:08 ` Ming Lei 2020-10-14 1:37 ` Chao Leng 2020-10-14 1:37 ` Chao Leng 2020-10-14 2:02 ` Ming Lei 2020-10-14 2:02 ` Ming Lei 2020-10-14 2:32 ` Chao Leng 2020-10-14 2:32 ` Chao Leng 2020-10-14 2:41 ` Chao Leng 2020-10-14 2:41 ` Chao Leng 2020-10-14 3:34 ` Ming Lei 2020-10-14 3:34 ` Ming Lei 2020-10-14 9:39 ` Chao Leng 2020-10-14 9:39 ` Chao Leng 2020-10-14 9:56 ` Ming Lei 2020-10-14 9:56 ` Ming Lei 2020-10-15 6:05 ` Chao Leng 2020-10-15 6:05 ` Chao Leng 2020-10-15 7:50 ` Ming Lei 2020-10-15 7:50 ` Ming Lei 2020-10-15 10:05 ` Chao Leng 2020-10-15 10:05 ` Chao Leng 2020-10-14 1:32 ` Chao Leng 2020-10-14 1:32 ` Chao Leng 2020-10-13 22:31 ` Sagi Grimberg 2020-10-13 22:31 ` Sagi Grimberg 2020-10-14 1:25 ` Chao Leng [this message] 2020-10-14 1:25 ` Chao Leng 2020-10-09 8:11 ` Sagi Grimberg 2020-10-09 8:11 ` Sagi Grimberg
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=dba6f24d-7d4f-a89e-047d-9d63837084dd@huawei.com \ --to=lengchao@huawei.com \ --cc=axboe@kernel.dk \ --cc=hch@lst.de \ --cc=kbusch@kernel.org \ --cc=linux-block@vger.kernel.org \ --cc=linux-nvme@lists.infradead.org \ --cc=ming.lei@redhat.com \ --cc=sagi@grimberg.me \ --cc=yi.zhang@redhat.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.