From: Keith Busch <keith.busch@intel.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org,
Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 2/3] scsi: Do not rely on blk-mq for double completions
Date: Wed, 14 Nov 2018 11:00:18 -0700 [thread overview]
Message-ID: <20181114180018.GC11416@localhost.localdomain> (raw)
In-Reply-To: <1542217896.100259.2.camel@acm.org>
On Wed, Nov 14, 2018 at 09:51:36AM -0800, Bart Van Assche wrote:
> Regarding this patch: I think this patch introduces a subtle but severe bug
> in the SCSI core, namely that if an abort is processed concurrently with
> request completion with "fake timeout" enabled that the abort is ignored.
That requires the following occur concurrently:
1. A real completion
2. A real timeout
3. A fake timeout
That can't happen on a production kernel, and highly improbable
on the fake one. We can still fix it by having scsi timeout return
BLK_EH_RESET_TIMER in this case. I didn't like adding code just to work
around error injection, but there isn't a good alternative at the moment.
next prev parent reply other threads:[~2018-11-14 18:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-14 16:25 [PATCH 1/3] blk-mq: Return true if request was completed Keith Busch
2018-11-14 16:26 ` [PATCH 2/3] scsi: Do not rely on blk-mq for double completions Keith Busch
2018-11-14 17:51 ` Bart Van Assche
2018-11-14 18:00 ` Keith Busch [this message]
2018-11-14 18:10 ` Keith Busch
2018-11-14 16:26 ` [PATCH 3/3] blk-mq: Simplify request completion state Keith Busch
-- strict thread matches above, loose matches on Subject: below --
2018-11-15 17:56 [PATCH 1/3] blk-mq: Return true if request was completed Keith Busch
2018-11-15 17:56 ` [PATCH 2/3] scsi: Do not rely on blk-mq for double completions Keith Busch
2018-11-15 17:57 ` Keith Busch
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