+
+ /*
+ * Increment the counter before taking the lock so that
+ * a potential waker won't miss a to-be-slept task that is
+ * waiting for the spinlock. This is safe as all queue_lock()
+ * users end up calling queue_me(). Similarly, for housekeeping,
+ * decrement the counter at queue_unlock() when some error has
+ * occurred and we don't end up adding the task to the list.
+ */
+ hb_waiters_inc(hb);
+