From: Jens Axboe <axboe@kernel.dk>
To: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Sitsofe Wheeler <sitsofe@yahoo.com>,
Borislav Petkov <bp@alien8.de>, Meelis Roos <mroos@linux.ee>,
Andrew Morton <akpm@linux-foundation.org>,
Kay Sievers <kay.sievers@vrfy.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH UPDATED 2/3 v2.6.39-rc7] block: make disk_block_events() properly wait for work cancellation
Date: Tue, 17 May 2011 21:34:58 +0200 [thread overview]
Message-ID: <4DD2CDE2.60604@kernel.dk> (raw)
In-Reply-To: <20110517154748.GS20624@htj.dyndns.org>
On 2011-05-17 17:47, Tejun Heo wrote:
> disk_block_events() should guarantee that the event work is not in
> flight on return and once blocked it shouldn't issue further
> cancellations.
>
> Because there was no synchronization between the first blocker doing
> cancel_delayed_work_sync() and the following blockers, the following
> blockers could finish before cancellation was complete, which broke
> both guarantees - event work could be in flight and cancellation could
> happen after return.
>
> This bug triggered WARN_ON_ONCE() in disk_clear_events() reported in
> bug#34662.
>
> https://bugzilla.kernel.org/show_bug.cgi?id=34662
>
> Fix it by adding an outer mutex which protects both block count
> manipulation and work cancellation.
>
> -v2: Use outer mutex instead of bit waitqueue per Linus.
Thanks, much cleaner indeed. I've rebased for-linus. BTW, this is patch
3/3, not 2/3. Had me confused for a while, the numbering on the initial
series was off as well.
I'll let this simmer until tomorrow, then send out the pull request.
--
Jens Axboe
next prev parent reply other threads:[~2011-05-17 19:35 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-17 10:27 [PATCH RESEND 1/3 v2.6.39-rc7] block: don't use non-syncing event blocking in disk_check_events() Tejun Heo
2011-05-17 10:28 ` [PATCH RESEND 2/3 v2.6.39-rc7] block: remove non-syncing __disk_block_events() and fold it into disk_block_events() Tejun Heo
2011-05-17 10:28 ` [PATCH RESEND 2/3 v2.6.39-rc7] block: make disk_block_events() properly wait for work cancellation Tejun Heo
2011-05-17 14:46 ` Linus Torvalds
2011-05-17 15:11 ` Tejun Heo
2011-05-17 15:15 ` Linus Torvalds
2011-05-17 15:27 ` Tejun Heo
2011-05-17 22:40 ` Linus Torvalds
2011-05-18 5:07 ` Tejun Heo
2011-05-18 9:46 ` Linus Torvalds
2011-05-18 10:04 ` Tejun Heo
2011-05-18 11:07 ` Tejun Heo
2011-05-18 10:26 ` Jens Axboe
2011-05-17 15:47 ` [PATCH UPDATED " Tejun Heo
2011-05-17 19:34 ` Jens Axboe [this message]
2011-05-17 20:22 ` Borislav Petkov
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