linux-kernel - Re: Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disable

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Message-ID: <Pine.LNX.4.64.0806231115420.22557@schroedinger.engr.sgi.com>
Date:	Mon, 23 Jun 2008 11:20:10 -0700 (PDT)
From:	Christoph Lameter <clameter@....com>
To:	Petr Tesarik <ptesarik@...e.cz>
cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin
 with irqs disable

On Mon, 23 Jun 2008, Petr Tesarik wrote:

> Maybe I'm just blind, but doesn't this change effectively disable any
> arch-specific optimized code for _raw_*_lock?

True.  Only the __raw_xxx_trylock is still used.

> If CONFIG_DEBUG_LOCK_ALLOC is set, then CONFIG_DEBUG_SPINLOCK must also
> be set, so in that case the debugging versions of _raw_*_lock are used.
> But if CONFIG_DEBUG_LOCK_ALLOC is _not_ set, then the locks are built
> with _trylock and _can_lock primitives.
> 
> What am I missing here?

It is good that the locks are build with _trylock and _can_lock because 
then we can reenable interrupts while spinning.


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