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x86/cmpxchg: add a locked add() helper

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Mostly to remove some conditional code in spinlock.h.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
This commit is contained in:
Jeremy Fitzhardinge
2011-09-28 11:49:28 -07:00
parent 4a7f340c6a
commit 3d94ae0c70
2 changed files with 43 additions and 14 deletions
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15
arch/x86/include/asm/spinlock.h
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@@ -79,23 +79,10 @@ static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)
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)
{