[rfc] [patch 2/2] spin_lock_irq: Enable interrupts while spinning -- x86_64 implementation

[Ravikiran G Thirumalai <kiran@scalex86.org>]

Implement interrupt enabling while spinning for lock for spin_lock_irq

Signed-off by: Pravin B. Shelar <pravin.shelar@calsoftinc.com>
Signed-off by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off by: Shai Fultheim <shai@scalex86.org>

Index: linux-2.6.20-rc1/include/asm-x86_64/spinlock.h
===================================================================
--- linux-2.6.20-rc1.orig/include/asm-x86_64/spinlock.h	2006-12-28 17:18:32.142775000 -0800
+++ linux-2.6.20-rc1/include/asm-x86_64/spinlock.h	2006-12-29 14:05:04.012954000 -0800
@@ -63,7 +63,21 @@ static inline void __raw_spin_lock_flags
 		"5:\n\t"
 		: "+m" (lock->slock) : "r" ((unsigned)flags) : "memory");
 }
-#define __raw_spin_lock_irq(lock) __raw_spin_lock(lock)
+static inline void __raw_spin_lock_irq(raw_spinlock_t *lock)
+{
+	asm volatile(
+		"\n1:\t"
+		LOCK_PREFIX " ; decl %0\n\t"
+		"jns 2f\n"
+		"sti\n"		/* Enable interrupts during spin */
+		"3:\n"
+		"rep;nop\n\t"
+		"cmpl $0,%0\n\t"
+		"jle 3b\n\t"
+		"cli\n"
+		"jmp 1b\n"
+		"2:\t" : "+m" (lock->slock) : : "memory");
+}
 #endif
 
 static inline int __raw_spin_trylock(raw_spinlock_t *lock)