diff options
Diffstat (limited to 'arch/x86/include/asm/spinlock.h')
| -rw-r--r-- | arch/x86/include/asm/spinlock.h | 60 |
1 files changed, 30 insertions, 30 deletions
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index ea2a04f69ca9..5240cdefa683 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -57,21 +57,21 @@ #if (NR_CPUS < 256) static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { - unsigned short inc = 1 << TICKET_SHIFT; - - asm volatile ( - LOCK_PREFIX "xaddw %w0, %1\n" - "1:\t" - "cmpb %h0, %b0\n\t" - "je 2f\n\t" - "rep ; nop\n\t" - "movb %1, %b0\n\t" - /* don't need lfence here, because loads are in-order */ - "jmp 1b\n" - "2:" - : "+Q" (inc), "+m" (lock->slock) - : - : "memory", "cc"); + register union { + struct __raw_tickets tickets; + unsigned short slock; + } inc = { .slock = 1 << TICKET_SHIFT }; + + asm volatile (LOCK_PREFIX "xaddw %w0, %1\n" + : "+Q" (inc), "+m" (lock->slock) : : "memory", "cc"); + + for (;;) { + if (inc.tickets.head == inc.tickets.tail) + break; + cpu_relax(); + inc.tickets.head = ACCESS_ONCE(lock->tickets.head); + } + barrier(); /* make sure nothing creeps before the lock is taken */ } static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) @@ -104,22 +104,22 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { unsigned inc = 1 << TICKET_SHIFT; - unsigned tmp; + __ticket_t tmp; - asm volatile(LOCK_PREFIX "xaddl %0, %1\n" - "movzwl %w0, %2\n\t" - "shrl $16, %0\n\t" - "1:\t" - "cmpl %0, %2\n\t" - "je 2f\n\t" - "rep ; nop\n\t" - "movzwl %1, %2\n\t" - /* don't need lfence here, because loads are in-order */ - "jmp 1b\n" - "2:" - : "+r" (inc), "+m" (lock->slock), "=&r" (tmp) - : - : "memory", "cc"); + asm volatile(LOCK_PREFIX "xaddl %0, %1\n\t" + : "+r" (inc), "+m" (lock->slock) + : : "memory", "cc"); + + tmp = inc; + inc >>= TICKET_SHIFT; + + for (;;) { + if ((__ticket_t)inc == tmp) + break; + cpu_relax(); + tmp = ACCESS_ONCE(lock->tickets.head); + } + barrier(); /* make sure nothing creeps before the lock is taken */ } static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) |