linux-kernel - Re: [PATCH v5 1/6] nbd: don't handle response without a corresponding request message

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Date:   Tue, 14 Sep 2021 08:54:27 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Yu Kuai <yukuai3@...wei.com>
Cc:     axboe@...nel.dk, josef@...icpanda.com, hch@...radead.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        nbd@...er.debian.org, yi.zhang@...wei.com
Subject: Re: [PATCH v5 1/6] nbd: don't handle response without a
 corresponding request message

On Thu, Sep 09, 2021 at 10:12:51PM +0800, Yu Kuai wrote:
> While handling a response message from server, nbd_read_stat() will
> try to get request by tag, and then complete the request. However,
> this is problematic if nbd haven't sent a corresponding request
> message:
> 
> t1                      t2
>                         submit_bio
>                          nbd_queue_rq
>                           blk_mq_start_request
> recv_work
>  nbd_read_stat
>   blk_mq_tag_to_rq
>  blk_mq_complete_request
>                           nbd_send_cmd
> 
> Thus add a new cmd flag 'NBD_CMD_INFLIGHT', it will be set in
> nbd_send_cmd() and checked in nbd_read_stat().
> 
> Noted that this patch can't fix that blk_mq_tag_to_rq() might
> return a freed request, and this will be fixed in following
> patches.
> 
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>

Looks fine:

Reviewed-by: Ming Lei <ming.lei@...hat.com>

-- 
Ming