From: Tejun Heo <tj@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>, 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 RESEND 2/3 v2.6.39-rc7] block: make disk_block_events() properly wait for work cancellation
Date: Wed, 18 May 2011 13:07:32 +0200 [thread overview]
Message-ID: <20110518110732.GW20624@htj.dyndns.org> (raw)
In-Reply-To: <20110518100451.GV20624@htj.dyndns.org>
On Wed, May 18, 2011 at 12:04:51PM +0200, Tejun Heo wrote:
> Yeap, the problem was unblock/check being allowed to be called without
> sleeping context, which isn't used anymore and was broken due to
> cancellation race. We can just enclose the whole thing inside per-ev
> mutex and everything should be simple and fine. I'll post patches
> soon.
Oops, spoke too soon. Converting to mutex creates a circular
dependency. disk_block_events() acquires ev->lock and waits for
ev->dwork to finish, but ev->dwork also needs to acquire ev->lock to
update event states. So, no matter how we twist this, we need two
locks or a lock and a completion. The mutex approach seems simple
enough, so I suggest leaving it like that.
Thanks.
--
tejun
next prev parent reply other threads:[~2011-05-18 11:07 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 [this message]
2011-05-18 10:26 ` Jens Axboe
2011-05-17 15:47 ` [PATCH UPDATED " Tejun Heo
2011-05-17 19:34 ` Jens Axboe
2011-05-17 20:22 ` Borislav Petkov
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