Il 17/06/2014 00:08, Waiman Long ha scritto:

quoted

+void __pv_queue_unlock(struct qspinlock *lock)
+{
+	int val = atomic_read(&lock->val);
+
+	native_queue_unlock(lock);
+
+	if (val & _Q_LOCKED_SLOW)
+		___pv_kick_head(lock);
+}
+

Again a race can happen here between the reading and writing of the lock
value. I can't think of a good way to do that without using cmpxchg.

Could you just use xchg on the locked byte?

Paolo