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Diffstat (limited to 'arch/powerpc/include/asm/spinlock.h')
-rw-r--r--arch/powerpc/include/asm/spinlock.h38
1 files changed, 32 insertions, 6 deletions
diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h
index 523673d7583c..fa37fe93bc02 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