[PATCH v3 3/5] nvme-fabrics: avoid double request completion for nvmf_fail_nonready_command

[Christoph Hellwig]

On Thu, Jan 21, 2021 at 09:58:37AM +0100, Hannes Reinecke wrote:
> On 1/21/21 8:03 AM, Chao Leng wrote:
>> When reconnect, the request may be completed with NVME_SC_HOST_PATH_ERROR
>> in nvmf_fail_nonready_command. The state of request will be changed to
>> MQ_RQ_IN_FLIGHT before call nvme_complete_rq. If free the request
>> asynchronously such as in nvme_submit_user_cmd, in extreme scenario
>> the request may be completed again in tear down process.
>> nvmf_fail_nonready_command do not need calling blk_mq_start_request
>> before complete the request. nvmf_fail_nonready_command should set
>> the state of request to MQ_RQ_COMPLETE before complete the request.
>>
>
> So what you are saying is that there is a race condition between
> blk_mq_start_request()
> and
> nvme_complete_request()

Between those to a teardwon that cancels all requests can come in.