Re: [PATCH v2] nvme-tcp: Check if request has started before processing it

[Christoph Hellwig]

On Wed, Mar 31, 2021 at 03:24:49PM -0700, Sagi Grimberg wrote:
>
>>> What we can do, though, is checking the 'state' field in the tcp
>>> request, and only allow completions for commands which are in a state
>>> allowing for completions.
>>>
>>> Let's see if I can whip up a patch.
>>
>> That would be great.  BTW in the crash dump I am looking at now, it
>> looks like pdu->command_id was zero in nvme_tcp_recv_data(), and
>> blk_mq_tag_to_rq() returned a request struct that had not been used.
>> So I think we do need to check that the tag was actually allocated.
>
> request tag can't be zero? I forget...

Of course it can.  But the reserved tags are before the normal tags,
so 0 would be a reserved tag for nvme.