Revert "Do notifications synchronously"

This reverts commit 6ee2ac3.

p2p/net/swarm/swarm.go

@@ -208,6 +208,9 @@ func (s *Swarm) addConn(tc transport.Conn, dir inet.Direction) (*Conn, error) {
 	// * The other will be decremented when Conn.start exits.
 	s.refs.Add(2)
 
+	// Take the notification lock before releasing the conns lock to block
+	// Disconnect notifications until after the Connect notifications done.
+	c.notifyLk.Lock()
 	s.conns.Unlock()
 
 	// We have a connection now. Cancel all other in-progress dials.
@@ -217,6 +220,7 @@ func (s *Swarm) addConn(tc transport.Conn, dir inet.Direction) (*Conn, error) {
 	s.notifyAll(func(f inet.Notifiee) {
 		f.Connected(s, c)
 	})
+	c.notifyLk.Unlock()
 
 	c.start()
 
@@ -434,10 +438,18 @@ func (s *Swarm) Backoff() *DialBackoff {
 
 // notifyAll sends a signal to all Notifiees
 func (s *Swarm) notifyAll(notify func(inet.Notifiee)) {
+	var wg sync.WaitGroup
+
 	s.notifs.RLock()
+	wg.Add(len(s.notifs.m))
 	for f := range s.notifs.m {
-		notify(f)
+		go func(f inet.Notifiee) {
+			defer wg.Done()
+			notify(f)
+		}(f)
 	}
+
+	wg.Wait()
 	s.notifs.RUnlock()
 }
 

p2p/net/swarm/swarm_conn.go

@@ -65,10 +65,17 @@ func (c *Conn) doClose() {
 		s.Reset()
 	}
 
-	c.swarm.notifyAll(func(f inet.Notifiee) {
-		f.Disconnected(c.swarm, c)
-	})
-	c.swarm.refs.Done() // taken in Swarm.addConn
+	// do this in a goroutine to avoid deadlocking if we call close in an open notification.
+	go func() {
+		// prevents us from issuing close notifications before finishing the open notifications
+		c.notifyLk.Lock()
+		defer c.notifyLk.Unlock()
+
+		c.swarm.notifyAll(func(f inet.Notifiee) {
+			f.Disconnected(c.swarm, c)
+		})
+		c.swarm.refs.Done() // taken in Swarm.addConn
+	}()
 }
 
 func (c *Conn) removeStream(s *Stream) {