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Date: Fri, 30 Apr 2004 00:07:51 -0700
From: Andrew Morton <akpm@osdl.org>
To: Keith Owens <kaos@sgi.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [patch] 2.6.6-rc3 Allow architectures to reenable interrupts on
 contended spinlocks
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Keith Owens <kaos@sgi.com> wrote:
>
>  As requested by Linus, update all architectures to add the common
>  infrastructure.  Tested on ia64 and i386.
> 
> 
>  Enable interrupts while waiting for a disabled spinlock, but only if
>  interrupts were enabled before issuing spin_lock_irqsave().

Please test stuff with CONFIG_SMP=n?

include/linux/sched.h: In function `dequeue_signal_lock':
include/linux/sched.h:795: warning: implicit declaration of function `_raw_spin_lock_flags'

--- 25/include/linux/spinlock.h~allow-architectures-to-reenable-interrupts-on-contended-spinlocks-fix	2004-04-29 23:53:48.357203736 -0700
+++ 25-akpm/include/linux/spinlock.h	2004-04-29 23:54:15.053145336 -0700
@@ -46,6 +46,8 @@
 
 #else
 
+#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
+
 #if !defined(CONFIG_PREEMPT) && !defined(CONFIG_DEBUG_SPINLOCK)
 # define atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)
 # define ATOMIC_DEC_AND_LOCK

_


The feature is only enabled for spin_lock_irqsave().  Should it not also do
something about spin_lock_irq()?