From: "jianchao.wang" <jianchao.w.wang@oracle.com>
To: Bart Van Assche <Bart.VanAssche@wdc.com>,
"axboe@kernel.dk" <axboe@kernel.dk>
Cc: "hch@lst.de" <hch@lst.de>, "tj@kernel.org" <tj@kernel.org>,
"israelr@mellanox.com" <israelr@mellanox.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"maxg@mellanox.com" <maxg@mellanox.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
"sagi@grimberg.me" <sagi@grimberg.me>
Subject: Re: [PATCH v4] blk-mq: Fix race conditions in request timeout handling
Date: Tue, 10 Apr 2018 22:32:20 +0800 [thread overview]
Message-ID: <a073fa7a-d23e-dafa-0d7d-e5caababe7b0@oracle.com> (raw)
In-Reply-To: <1131f89179501c54c04d61d81bc46a83ba87df27.camel@wdc.com>
Hi Bart
Thanks for your kindly response.
On 04/10/2018 09:01 PM, Bart Van Assche wrote:
> On Tue, 2018-04-10 at 15:59 +0800, jianchao.wang wrote:
>> If yes, how does the timeout handler get the freed request when the tag has been freed ?
>
> Hello Jianchao,
>
> Have you noticed that the timeout handler does not check whether or not the request
> tag is freed? Additionally, I don't think it would be possible to add such a check
> to the timeout code without introducing a new race condition.
Doesn't blk_mq_queue_tag_busy_iter only iterate the tags that has been allocated/set ?
When the request is freed, the tag will be cleared through blk_mq_put_tag->sbitmap_queue_clear
Do I miss something else ?
Thanks
Jianchao
>
>
next prev parent reply other threads:[~2018-04-10 14:32 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-10 1:34 [PATCH v4] blk-mq: Fix race conditions in request timeout handling Bart Van Assche
2018-04-10 7:59 ` jianchao.wang
2018-04-10 10:04 ` Ming Lei
2018-04-10 12:04 ` Shan Hai
2018-04-10 13:01 ` Bart Van Assche
2018-04-10 14:32 ` jianchao.wang [this message]
2018-04-10 8:41 ` Ming Lei
2018-04-10 12:58 ` Bart Van Assche
2018-04-10 13:55 ` Ming Lei
2018-04-10 14:09 ` Bart Van Assche
2018-04-10 14:30 ` Ming Lei
2018-04-10 15:02 ` Bart Van Assche
2018-04-10 15:25 ` Ming Lei
2018-04-10 15:30 ` tj
2018-04-10 15:38 ` Ming Lei
2018-04-10 15:40 ` tj
2018-04-10 21:33 ` tj
2018-04-10 21:46 ` Bart Van Assche
2018-04-10 21:54 ` tj
2018-04-11 12:50 ` Bart Van Assche
2018-04-11 14:16 ` tj
2018-04-11 18:38 ` Martin Steigerwald
2018-04-11 14:24 ` Sagi Grimberg
2018-04-11 14:43 ` tj
2018-04-11 16:16 ` Israel Rukshin
2018-04-11 17:07 ` tj
2018-04-11 21:31 ` tj
2018-04-12 8:59 ` Israel Rukshin
2018-04-12 13:35 ` tj
2018-04-15 12:28 ` Israel Rukshin
2018-04-18 16:34 ` Bart Van Assche
2018-04-10 9:55 ` Christoph Hellwig
2018-04-10 13:26 ` Bart Van Assche
2018-04-10 14:50 ` hch
2018-04-10 14:41 ` Jens Axboe
2018-04-10 14:20 ` Tejun Heo
2018-04-10 14:30 ` Bart Van Assche
2018-04-10 14:33 ` tj
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