From: Andi Kleen <ak@suse.de>
Date: Thu, 7 Dec 2006 01:14:00 +0000 (+0100)
Subject: [PATCH] x86-64: Don't keep interrupts disabled while spinning in spinlocks
X-Git-Tag: v2.6.20-rc1~145^2^2~8^2~148
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=87e1652c7863b9ae406ff37f33c7ec2bb494d7b1;p=linux-2.6

[PATCH] x86-64: Don't keep interrupts disabled while spinning in spinlocks

Follows i386.

Based on patch from some folks at Google (MikeW, Edward G.?), but
completely redone by AK.

Signed-off-by: Andi Kleen <ak@suse.de>
---

diff --git a/include/asm-x86_64/spinlock.h b/include/asm-x86_64/spinlock.h
index 05ef097ba5..88bf981e73 100644
--- a/include/asm-x86_64/spinlock.h
+++ b/include/asm-x86_64/spinlock.h
@@ -36,7 +36,34 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
 		"2:\t" : "=m" (lock->slock) : : "memory");
 }
 
-#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
+/*
+ * Same as __raw_spin_lock, but reenable interrupts during spinning.
+ */
+#ifndef CONFIG_PROVE_LOCKING
+static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
+{
+	asm volatile(
+		"\n1:\t"
+		LOCK_PREFIX " ; decl %0\n\t"
+		"jns 5f\n"
+		"testl $0x200, %1\n\t"	/* interrupts were disabled? */
+		"jz 4f\n\t"
+	        "sti\n"
+		"3:\t"
+		"rep;nop\n\t"
+		"cmpl $0, %0\n\t"
+		"jle 3b\n\t"
+		"cli\n\t"
+		"jmp 1b\n"
+		"4:\t"
+		"rep;nop\n\t"
+		"cmpl $0, %0\n\t"
+		"jg 1b\n\t"
+		"jmp 4b\n"
+		"5:\n\t"
+		: "+m" (lock->slock) : "r" ((unsigned)flags) : "memory");
+}
+#endif
 
 static inline int __raw_spin_trylock(raw_spinlock_t *lock)
 {