[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>

1 files changed, 28 insertions, 1 deletions

diff --git a/include/asm-x86_64/spinlock.h b/include/asm-x86_64/spinlock.h
index 05ef097ba55..88bf981e73c 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)
 {