+static bool sunrpc_waitqueue_active(wait_queue_head_t *wq)
+{
+ if (!wq)
+ return false;
+ /*
+ * There should normally be a memory * barrier here--see
+ * wq_has_sleeper().
+ *
+ * It appears that isn't currently necessary, though, basically
+ * because callers all appear to have sufficient memory barriers
+ * between the time the relevant change is made and the
+ * time they call these callbacks.
+ *
+ * The nfsd code itself doesn't actually explicitly wait on
+ * these waitqueues, but it may wait on them for example in
+ * sendpage() or sendmsg() calls. (And those may be the only
+ * places, since it it uses nonblocking reads.)
+ *
+ * Maybe we should add the memory barriers anyway, but these are
+ * hot paths so we'd need to be convinced there's no sigificant
+ * penalty.
+ */
+ return waitqueue_active(wq);
+}
+