From: Keith Owens <kaos@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [patch 2.6.9] Avoid a rare deadlock during unwind
Date: Fri, 22 Oct 2004 10:14:26 +0000 [thread overview]
Message-ID: <5642.1098440066@ocs3.ocs.com.au> (raw)
In-Reply-To: <9718.1098174005@kao2.melbourne.sgi.com>
On Fri, 22 Oct 2004 20:10:08 +1000,
Keith Owens <kaos@sgi.com> wrote:
>On Fri, 22 Oct 2004 02:27:30 -0700,
>David Mosberger <davidm@napali.hpl.hp.com> wrote:
>>>>>>> On Fri, 22 Oct 2004 00:44:35 +1000, Keith Owens <kaos@sgi.com> said:
>> Keith> o if both the unw.lock spinlock and a script's read-write lock must be
>> Keith> acquired using a method that might sleep, then the read-write lock
>> Keith> must be acquired first.
>>
>> Keith> adding "using a method that might sleep". The only read-write lock
>> Keith> code under spinlock(unw.lock) is write_trylock(), which never sleeps.
>> Keith> If you agree with this analysis, then I am happy to update the comment.
>>
>>No, the comment was intending to establish the lock hierarchy. If there
>>are no other paths where the locks are acquire in the other order, then
>>it's OK. I'd just reverse the comment to match the (new) reality.
>
>Reversing the comment would also be wrong. You are not allowed to
>sleep while holding a spinlock.
Ignore that, brain malfunction. read/write_lock does not sleep.
read_lock != semaphore.
next prev parent reply other threads:[~2004-10-22 10:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-19 8:20 [patch 2.6.9] Avoid a rare deadlock during unwind Keith Owens
2004-10-21 14:30 ` David Mosberger
2004-10-21 14:44 ` Keith Owens
2004-10-22 9:27 ` David Mosberger
2004-10-22 10:10 ` Keith Owens
2004-10-22 10:14 ` Keith Owens [this message]
2004-10-22 10:50 ` David Mosberger
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