Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [RFC PATCH v3 3/3] blk-mq: Lockout tagset iterator when exiting
 elevator
To:     John Garry <john.garry@huawei.com>, hare@suse.de,
        ming.lei@redhat.com, axboe@kernel.dk, hch@lst.de
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        pragalla@codeaurora.org, kashyap.desai@broadcom.com,
        yuyufen@huawei.com
References: <1614957294-188540-1-git-send-email-john.garry@huawei.com>
 <1614957294-188540-4-git-send-email-john.garry@huawei.com>
 <48a3cf78-3f6d-c13c-bca2-1f8277817b45@acm.org>
 <9c9360bf-7ca9-5c8f-c61d-441044f9c78f@huawei.com>
 <784a3686-cb54-561d-740c-30e0b3f46df8@acm.org>
 <f60dc68f-9206-2bfb-950e-cb312f1c4c8b@huawei.com>
From:   Bart Van Assche <bvanassche@acm.org>
Message-ID: <de3dec73-c8fc-d14f-5bbb-7023ccc6b57e@acm.org>
Date:   Tue, 9 Mar 2021 11:21:41 -0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.8.0
MIME-Version: 1.0
In-Reply-To: <f60dc68f-9206-2bfb-950e-cb312f1c4c8b@huawei.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 3/9/21 9:47 AM, John Garry wrote:
> This does fall over if some tags are allocated without associated
> request queue, which I do not know exists.

The only tag allocation mechanism I know of is blk_mq_get_tag(). The
only blk_mq_get_tag() callers I know of are __blk_mq_alloc_request() and
blk_mq_alloc_request_hctx(). So I think all allocated tags are
associated with a request queue.

Regarding this patch series, I have shared the feedback I wanted to
share so I would appreciate it if someone else could also take a look.

Thanks,

Bart.