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Subject: Re: [PATCH] nbd: add a missed nbd_config_put() in nbd_xmit_timeout()
To:     Sun Ke <sunke32@huawei.com>, josef@toxicpanda.com, axboe@kernel.dk,
        linux-block@vger.kernel.org, nbd@other.debian.org,
        linux-kernel@vger.kernel.org
References: <1565613086-13776-1-git-send-email-sunke32@huawei.com>
From:   Mike Christie <mchristi@redhat.com>
Message-ID: <5D518714.5000408@redhat.com>
Date:   Mon, 12 Aug 2019 10:34:44 -0500
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On 08/12/2019 07:31 AM, Sun Ke wrote:
> When try to get the lock failed, before return, execute the
> nbd_config_put() to decrease the nbd->config_refs.
> 
> If the nbd->config_refs is added but not decreased. Then will not
> execute nbd_clear_sock() in nbd_config_put(). bd->task_setup will
> not be cleared away. Finally, print"Device being setup by another
> task" in nbd_add_sock() and nbd device can not be reused.
> 
> Fixes: 8f3ea35929a0 ("nbd: handle unexpected replies better")
> Signed-off-by: Sun Ke <sunke32@huawei.com>
> ---
>  drivers/block/nbd.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index e21d2de..a69a90a 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -357,8 +357,10 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
>  	}
>  	config = nbd->config;
>  
> -	if (!mutex_trylock(&cmd->lock))
> +	if (!mutex_trylock(&cmd->lock)) {
> +		nbd_config_put(nbd);
>  		return BLK_EH_RESET_TIMER;
> +	}
>  
>  	if (config->num_connections > 1) {
>  		dev_err_ratelimited(nbd_to_dev(nbd),
> 

I just sent the same patch

https://www.spinics.net/lists/linux-block/msg43718.html

here

https://www.spinics.net/lists/linux-block/msg43715.html

so it looks good to me.

Reviewed-by: Mike Christie <mchristi@redhat.com>