From 68302ae430d388a0118a8ce2a1abb5f87b737ef6 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Thu, 23 Jun 2011 18:19:15 -0700 Subject: [PATCH] x86, ticketlock: Use C for __ticket_spin_unlock If we don't need to use a locked inc for unlock, then implement it in C. Signed-off-by: Jeremy Fitzhardinge Link: http://lkml.kernel.org/r/aa0d82c6e7a1c22a941da0df3c4ba58fea375074.1308878118.git.jeremy.fitzhardinge@citrix.com Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/spinlock.h | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index f48a6e32e487..704b0c39915e 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -33,9 +33,21 @@ * On PPro SMP or if we are using OOSTORE, we use a locked operation to unlock * (PPro errata 66, 92) */ -# define UNLOCK_LOCK_PREFIX LOCK_PREFIX +static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock) +{ + if (sizeof(lock->tickets.head) == sizeof(u8)) + asm (LOCK_PREFIX "incb %0" + : "+m" (lock->tickets.head) : : "memory"); + else + asm (LOCK_PREFIX "incw %0" + : "+m" (lock->tickets.head) : : "memory"); + +} #else -# define UNLOCK_LOCK_PREFIX +static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock) +{ + lock->tickets.head++; +} #endif /* @@ -93,14 +105,6 @@ static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) return tmp; } - -static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) -{ - asm volatile(UNLOCK_LOCK_PREFIX "incb %0" - : "+m" (lock->slock) - : - : "memory", "cc"); -} #else static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { @@ -144,15 +148,14 @@ static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) return tmp; } +#endif static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) { - asm volatile(UNLOCK_LOCK_PREFIX "incw %0" - : "+m" (lock->slock) - : - : "memory", "cc"); + barrier(); /* prevent reordering out of locked region */ + __ticket_unlock_release(lock); + barrier(); /* prevent reordering into locked region */ } -#endif static inline int __ticket_spin_is_locked(arch_spinlock_t *lock) { -- 2.39.5