From afb33f8c0d7dea8c48ae1c2e3af5b437aa8dd7bb Mon Sep 17 00:00:00 2001 From: Jiri Kosina Date: Mon, 12 Jan 2009 12:53:45 +0100 Subject: x86: remove byte locks Impact: cleanup Remove byte locks implementation, which was introduced by Jeremy in 8efcbab6 ("paravirt: introduce a "lock-byte" spinlock implementation"), but turned out to be dead code that is not used by any in-kernel virtualization guest (Xen uses its own variant of spinlocks implementation and KVM is not planning to move to byte locks). Signed-off-by: Jiri Kosina Signed-off-by: Ingo Molnar --- arch/x86/include/asm/spinlock.h | 66 ++--------------------------------------- 1 file changed, 2 insertions(+), 64 deletions(-) (limited to 'arch/x86/include/asm/spinlock.h') diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index d17c91981da2..2bd6b111a414 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -172,70 +172,8 @@ static inline int __ticket_spin_is_contended(raw_spinlock_t *lock) return (((tmp >> TICKET_SHIFT) - tmp) & ((1 << TICKET_SHIFT) - 1)) > 1; } -#ifdef CONFIG_PARAVIRT -/* - * Define virtualization-friendly old-style lock byte lock, for use in - * pv_lock_ops if desired. - * - * This differs from the pre-2.6.24 spinlock by always using xchgb - * rather than decb to take the lock; this allows it to use a - * zero-initialized lock structure. It also maintains a 1-byte - * contention counter, so that we can implement - * __byte_spin_is_contended. - */ -struct __byte_spinlock { - s8 lock; - s8 spinners; -}; - -static inline int __byte_spin_is_locked(raw_spinlock_t *lock) -{ - struct __byte_spinlock *bl = (struct __byte_spinlock *)lock; - return bl->lock != 0; -} - -static inline int __byte_spin_is_contended(raw_spinlock_t *lock) -{ - struct __byte_spinlock *bl = (struct __byte_spinlock *)lock; - return bl->spinners != 0; -} - -static inline void __byte_spin_lock(raw_spinlock_t *lock) -{ - struct __byte_spinlock *bl = (struct __byte_spinlock *)lock; - s8 val = 1; - - asm("1: xchgb %1, %0\n" - " test %1,%1\n" - " jz 3f\n" - " " LOCK_PREFIX "incb %2\n" - "2: rep;nop\n" - " cmpb $1, %0\n" - " je 2b\n" - " " LOCK_PREFIX "decb %2\n" - " jmp 1b\n" - "3:" - : "+m" (bl->lock), "+q" (val), "+m" (bl->spinners): : "memory"); -} - -static inline int __byte_spin_trylock(raw_spinlock_t *lock) -{ - struct __byte_spinlock *bl = (struct __byte_spinlock *)lock; - u8 old = 1; - - asm("xchgb %1,%0" - : "+m" (bl->lock), "+q" (old) : : "memory"); +#ifndef CONFIG_PARAVIRT - return old == 0; -} - -static inline void __byte_spin_unlock(raw_spinlock_t *lock) -{ - struct __byte_spinlock *bl = (struct __byte_spinlock *)lock; - smp_wmb(); - bl->lock = 0; -} -#else /* !CONFIG_PARAVIRT */ static inline int __raw_spin_is_locked(raw_spinlock_t *lock) { return __ticket_spin_is_locked(lock); @@ -267,7 +205,7 @@ static __always_inline void __raw_spin_lock_flags(raw_spinlock_t *lock, __raw_spin_lock(lock); } -#endif /* CONFIG_PARAVIRT */ +#endif static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock) { -- cgit v1.2.3