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From: Sagi Grimberg <sagi@grimberg.me>
To: Chao Leng <lengchao@huawei.com>, linux-nvme@lists.infradead.org
Cc: kbusch@kernel.org, axboe@fb.com, hch@lst.de
Subject: Re: [PATCH 0/3] avoid race between time out and tear down
Date: Tue, 20 Oct 2020 21:59:01 -0700	[thread overview]
Message-ID: <b60f34ea-86f1-ef86-8e1f-b156b7681699@grimberg.me> (raw)
In-Reply-To: <3d5b96dd-4e0f-758a-4175-e69fef0b8c34@huawei.com>


>>> Avoid race between time out and tear down for rdma and tcp.
>>
>> This patchset overall looks good, but we still need the patch that
>> avoids double completion:
>>
>> -- 
>> 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)) {
> Yes, this patch is need. and samely for nvme_cancel_request.
> This will fix the race with asynchronous completion.
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index e85f6304efd7..1e838d952096 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -338,7 +338,7 @@ bool nvme_cancel_request(struct request *req, void 
> *data, bool reserved)
>                                  "Cancelling I/O %d", req->tag);
> 
>          /* don't abort one completed request */
> -       if (blk_mq_request_completed(req))
> +       if (blk_mq_request_completed(req) || !blk_mq_request_started(rq))
>                  return true;
> 
>          nvme_req(req)->status = NVME_SC_HOST_ABORTED_CMD;

This one is unneeded because blk_mq_tagset_busy_iter checks that the
request has started...

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  reply	other threads:[~2020-10-21  4:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-20  9:08 [PATCH 0/3] avoid race between time out and tear down Chao Leng
2020-10-20 18:43 ` Sagi Grimberg
2020-10-21  2:16   ` Chao Leng
2020-10-21  4:59     ` Sagi Grimberg [this message]
2020-10-21  6:51       ` Chao Leng
2020-10-21  8:53         ` Sagi Grimberg
2020-10-22  1:58           ` Chao Leng

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