Re: [PATCH v3] powerpc: spinlock: Fix spin_unlock_wait()

+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 (!arch_spin_value_unlocked(*lock)) {
+		HMT_low();
+		if (SHARED_PROCESSOR)
+			__spin_yield(lock);
+	}
+	HMT_medium();
+
+out:
+	smp_mb();
+}