linux-kernel - Re: [PATCH] nbd: add a missed nbd_config_put() in nbd_xmit

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Date:   Wed, 14 Aug 2019 22:13:20 -0500
From:   Mike Christie <mchristi@...hat.com>
To:     "sunke (E)" <sunke32@...wei.com>, josef@...icpanda.com,
        axboe@...nel.dk, linux-block@...r.kernel.org, nbd@...er.debian.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nbd: add a missed nbd_config_put() in nbd_xmit_timeout()

Josef had ackd my patch for the same thing here:

https://www.spinics.net/lists/linux-block/msg43800.html

so maybe Jens will pick that up with the rest of the set Josef had acked:

https://www.spinics.net/lists/linux-block/msg43809.html

to make it easier.

On 08/14/2019 08:27 PM, sunke (E) wrote:
> ping
> 
> 在 2019/8/12 20:31, Sun Ke 写道:
>> 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@...wei.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),
>>
>