Re: [PATCH 1/4] blk-mq-tag: check for NULL rq when iterating tags

Jens Axboe
2017-08-03T20:40:23Z

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