From: Jens Axboe <axboe@kernel.dk>
To: Bart Van Assche <Bart.VanAssche@wdc.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Cc: "brking@linux.vnet.ibm.com" <brking@linux.vnet.ibm.com>
Subject: Re: [PATCH 1/4] blk-mq-tag: check for NULL rq when iterating tags
Date: Thu, 3 Aug 2017 14:40:23 -0600 [thread overview]
Message-ID: <b1c18f36-87ea-fee8-e88b-03ecdfdf22af@kernel.dk> (raw)
In-Reply-To: <549d568a-b32a-5d6c-7788-3f26a2ce58a2@kernel.dk>
On 08/03/2017 02:35 PM, Jens Axboe wrote:
>> I agree with what you wrote in the description of this patch.
>> However, since I have not yet found the code that clears tags->rqs[],
>> would it be possible to show me that code?
>
> Since it's been a month since I wrote this code, I went and looked
> too. My memory was that we set/clear it dynamically since we added
> scheduling, but looks like we don't clear it. The race is still valid
> for when someone runs a tag check in parallel with someone allocating
> a tag, since there's a window of time where the tag bit is set, but
> ->rqs[tag] isn't set yet. That's probably the race I hit, not the
> completion race mentioned in the change log.
Rewrote the commit message:
http://git.kernel.dk/cgit/linux-block/commit/?h=mq-inflight&id=1908e43118e688e41ac8656edcf3e7a150f3f5081
--
Jens Axboe
next prev parent reply other threads:[~2017-08-03 20:40 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-03 20:01 [PATCH 0/4] block: more scalable inflight tracking Jens Axboe
2017-08-03 20:01 ` [PATCH 1/4] blk-mq-tag: check for NULL rq when iterating tags Jens Axboe
2017-08-03 20:29 ` Bart Van Assche
2017-08-03 20:35 ` Jens Axboe
2017-08-03 20:40 ` Jens Axboe [this message]
2017-08-03 20:50 ` Bart Van Assche
2017-08-03 20:56 ` Jens Axboe
2017-08-03 20:01 ` [PATCH 2/4] block: pass in queue to inflight accounting Jens Axboe
2017-08-03 20:35 ` Bart Van Assche
2017-08-03 20:37 ` Jens Axboe
2017-08-03 20:01 ` [PATCH 3/4] blk-mq: provide internal in-flight variant Jens Axboe
2017-08-03 20:41 ` Bart Van Assche
2017-08-03 20:45 ` Jens Axboe
2017-08-03 20:54 ` Bart Van Assche
2017-08-03 21:25 ` Bart Van Assche
2017-08-03 22:36 ` Jens Axboe
2017-08-04 11:17 ` Ming Lei
2017-08-04 13:55 ` Jens Axboe
2017-08-04 22:19 ` Ming Lei
2017-08-07 19:54 ` Brian King
2017-08-03 20:01 ` [PATCH 4/4] blk-mq: enable checking two part inflight counts at the same time Jens Axboe
2017-08-03 21:29 ` Bart Van Assche
2017-08-03 22:38 ` Jens Axboe
2017-08-03 22:30 ` Bart Van Assche
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