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From: Ming Lei <ming.lei@redhat.com>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: axboe@kernel.dk, josef@toxicpanda.com,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	nbd@other.debian.org, yi.zhang@huawei.com
Subject: Re: [PATCH v4 2/6] nbd: convert to use blk_mq_find_and_get_req()
Date: Wed, 8 Sep 2021 16:00:43 +0800	[thread overview]
Message-ID: <YThtq154oyROxBj9@T590> (raw)
In-Reply-To: <e295605c-bc8e-cbb9-ca51-1355fdfc0264@huawei.com>

On Wed, Sep 08, 2021 at 03:37:06PM +0800, yukuai (C) wrote:
> 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.

Not see it is addressed in patch 3 & 4, and it is one obvious fault in
patch 2, please fix it from beginning by moving the refcnt drop
into recv_work().

BTW, the approach in patch 3 looks fine, which is very similar with
SCSI's handling.

Thanks,
Ming


  reply	other threads:[~2021-09-08  8:00 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-07 14:01 [PATCH v4 0/6] handle unexpected message from server Yu Kuai
2021-09-07 14:01 ` [PATCH v4 1/6] blk-mq: export two symbols to get request by tag Yu Kuai
2021-09-07 14:01 ` [PATCH v4 2/6] nbd: convert to use blk_mq_find_and_get_req() Yu Kuai
2021-09-08  7:30   ` Ming Lei
2021-09-08  7:37     ` yukuai (C)
2021-09-08  8:00       ` Ming Lei [this message]
2021-09-08  8:29         ` yukuai (C)
2021-09-08  9:27           ` Ming Lei
2021-09-08 11:03             ` yukuai (C)
2021-09-07 14:01 ` [PATCH v4 3/6] nbd: don't handle response without a corresponding request message Yu Kuai
2021-09-07 14:01 ` [PATCH v4 4/6] nbd: make sure request completion won't concurrent Yu Kuai
2021-09-07 14:01 ` [PATCH v4 5/6] nbd: check sock index in nbd_read_stat() Yu Kuai
2021-09-07 14:01 ` [PATCH v4 6/6] nbd: don't start request if nbd_queue_rq() failed Yu Kuai
2021-09-09  6:41   ` Christoph Hellwig

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