diff options
Diffstat (limited to 'arch/powerpc/include/asm/spinlock.h')
| -rw-r--r-- | arch/powerpc/include/asm/spinlock.h | 38 |
1 files changed, 32 insertions, 6 deletions
diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h index 523673d75..fa37fe93b 100644 --- a/arch/powerpc/include/asm/spinlock.h +++ b/arch/powerpc/include/asm/spinlock.h @@ -162,12 +162,38 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) lock->slock = 0; } -#ifdef CONFIG_PPC64 -extern void arch_spin_unlock_wait(arch_spinlock_t *lock); -#else -#define arch_spin_unlock_wait(lock) \ - do { while (arch_spin_is_locked(lock)) cpu_relax(); } while (0) -#endif +static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) +{ + arch_spinlock_t lock_val; + + smp_mb(); + + /* + * Atomically load and store back the lock value (unchanged). This + * ensures that our observation of the lock value is ordered with + * respect to other lock operations. + */ + __asm__ __volatile__( +"1: " PPC_LWARX(%0, 0, %2, 0) "\n" +" stwcx. %0, 0, %2\n" +" bne- 1b\n" + : "=&r" (lock_val), "+m" (*lock) + : "r" (lock) + : "cr0", "xer"); + + if (arch_spin_value_unlocked(lock_val)) + goto out; + + while (lock->slock) { + HMT_low(); + if (SHARED_PROCESSOR) + __spin_yield(lock); + } + HMT_medium(); + +out: + smp_mb(); +} /* * Read-write spinlocks, allowing multiple readers |