x86/cmpxchg: add a locked add() helper
Mostly to remove some conditional code in spinlock.h.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 972c260..a82c2bf 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -79,23 +79,10 @@
return cmpxchg(&lock->head_tail, old.head_tail, new.head_tail) == old.head_tail;
}
-#if (NR_CPUS < 256)
static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
{
- asm volatile(UNLOCK_LOCK_PREFIX "incb %0"
- : "+m" (lock->head_tail)
- :
- : "memory", "cc");
+ __add(&lock->tickets.head, 1, UNLOCK_LOCK_PREFIX);
}
-#else
-static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
-{
- asm volatile(UNLOCK_LOCK_PREFIX "incw %0"
- : "+m" (lock->head_tail)
- :
- : "memory", "cc");
-}
-#endif
static inline int __ticket_spin_is_locked(arch_spinlock_t *lock)
{