Signal accounting in the explicit-reply path

Properly account signal count in the explicit-reply path (when source-
client gets immediately unblocked by 'signal_session_component::submit').
This patch prevents the delivery of superfluous signals with num == 0.

base/src/base/signal/signal.cc

@@ -241,6 +241,9 @@ Signal Signal_receiver::wait_for_signal()
 			/* invalidate current signal in context */
 			context->_curr_signal = Signal(0, 0);
 
+			if (result.num() == 0)
+				PWRN("returning signal with num == 0");
+
 			/* return last received signal */
 			return result;
 		}

base/src/core/signal_session_component.cc

@@ -86,7 +86,7 @@ void Signal_session_component::free_context(Signal_context_capability context_ca
 
 
 void Signal_session_component::submit(Signal_context_capability context_cap,
-                                      unsigned                   cnt)
+                                      unsigned                  cnt)
 {
 	Signal_context_component *context;
 	context = dynamic_cast<Signal_context_component *>

base/src/core/signal_source_component.cc

@@ -29,6 +29,13 @@ void Signal_source_component::submit(Signal_context_component *context,
                                      Ipc_ostream              *ostream,
                                      int                       cnt)
 {
+	/*
+	 * If the client does not block in 'wait_for_signal', the
+	 * signal will be delivered as result of the next
+	 * 'wait_for_signal' call.
+	 */
+	context->increment_signal_cnt(cnt);
+
 	/*
 	 * If the client is blocking at the signal source (indicated by
 	 * the valid reply capability), we wake him up.
@@ -43,17 +50,13 @@ void Signal_source_component::submit(Signal_context_component *context,
 		 * the reply capability.
 		 */
 		_reply_cap = Untyped_capability();
+		context->reset_signal_cnt();
+
+	} else {
+
+		if (!context->is_enqueued())
+			_signal_queue.enqueue(context);
 	}
-
-	/*
-	 * If the client does not block in 'wait_for_signal', the
-	 * signal will be delivered as result of the next
-	 * 'wait_for_signal' call.
-	 */
-	context->increment_signal_cnt(cnt);
-
-	if (!context->is_enqueued())
-		_signal_queue.enqueue(context);
 }