linux-kernel - Re: [PATCH v4 2/6] nbd: convert to use blk_mq_find_and_get

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Message-ID: <e295605c-bc8e-cbb9-ca51-1355fdfc0264@huawei.com>
Date:   Wed, 8 Sep 2021 15:37:06 +0800
From:   "yukuai (C)" <yukuai3@...wei.com>
To:     Ming Lei <ming.lei@...hat.com>
CC:     <axboe@...nel.dk>, <josef@...icpanda.com>,
        <linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <nbd@...er.debian.org>, <yi.zhang@...wei.com>
Subject: Re: [PATCH v4 2/6] nbd: convert to use blk_mq_find_and_get_req()

On 2021/09/08 15:30, Ming Lei wrote:

>> +put_req:
>> +	if (req)
>> +		blk_mq_put_rq_ref(req);
>>   	return ret ? ERR_PTR(ret) : cmd;
> 
> After the request's refcnt is dropped, it can be freed immediately, then
> one stale command is returned to caller.

Hi, Ming

It's right this patch leave this problem. Please take a look at patch 3
and patch 4, the problem should be fixed with these patches.

Thanks,
Kuai
> 
> Thanks,
> Ming
> 
> .
>