From: malahal@us.ibm.com
To: Jens Axboe <jens.axboe@oracle.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
linux-scsi@vger.kernel.org
Subject: Re: [PATCH] block: optimizations in blk_rq_timed_out_timer()
Date: Wed, 29 Oct 2008 11:21:04 -0700 [thread overview]
Message-ID: <20081029182104.GA543@us.ibm.com> (raw)
In-Reply-To: <20081029132614.GD31673@kernel.dk>
Jens Axboe [jens.axboe@oracle.com] wrote:
> > Yes, we should not access it although I don't think the request can be
> > freed while the existing code is accessing the deadline field. What
> > likely can happen is that we may call mod_timer with jiffies that is
> > older than current which would call the timer immediately...
>
> That would not call the timer immediately, that will not call it until
> jiffies reaches that value again. So you're looking at a minimum of 49
> days :-)
I remember the timer code treating "past" expiry times as special. If
not, then we have a real bug! It is also hard to guarantee in
blk_rq_timed_out_timer() that we always call mod_timer with future
expiry time!
--Malahal.
next prev parent reply other threads:[~2008-10-29 18:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-28 18:22 [PATCH] block: optimizations in blk_rq_timed_out_timer() malahal
2008-10-29 4:07 ` FUJITA Tomonori
2008-10-29 6:06 ` malahal
2008-10-29 13:26 ` Jens Axboe
2008-10-29 18:21 ` malahal [this message]
2008-10-30 2:33 ` FUJITA Tomonori
2008-10-30 7:49 ` Jens Axboe
2008-10-30 8:29 ` FUJITA Tomonori
2008-10-30 8:55 ` Jens Axboe
2008-10-30 10:29 ` FUJITA Tomonori
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