linux-kernel - Re: [PATCH] Fix x86_64 _spin_lock

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Message-ID: <44ED87AC.8070106@FreeBSD.org>
Date:	Thu, 24 Aug 2006 13:04:12 +0200
From:	Suleiman Souhlal <ssouhlal@...eBSD.org>
To:	Andi Kleen <ak@...e.de>
CC:	Edward Falk <efalk@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Fix x86_64 _spin_lock_irqsave()

Andi Kleen wrote:
> Edward Falk <efalk@...gle.com> writes:
> 
> 
>>Add spin_lock_string_flags and _raw_spin_lock_flags() to
>>asm-x86_64/spinlock.h so that _spin_lock_irqsave() has the same
>>semantics on x86_64 as it does on i386 and does *not* have interrupts
>>disabled while it is waiting for the lock.
> 
> 
> Did it fix anything for you?

I think this was to work around the fact that some buggy drivers try to 
grab spinlocks without disabling interrupts when they should, which 
would cause deadlocks when trying to rendez-vous every cpu via IPIs.

It's a bad idea to spin with interrupts disabled when they could very 
well be enabled, anyway.

-- Suleiman
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