fix data race in connection shutdown and channel close

channel.go

@@ -141,9 +141,12 @@ func (me *Channel) open() error {
 // Performs a request/response call for when the message is not NoWait and is
 // specified as Synchronous.
 func (me *Channel) call(req message, res ...message) error {
+	me.m.Lock()
 	if err := me.send(me, req); err != nil {
+		me.m.Unlock()
 		return err
 	}
+	me.m.Unlock()
 
 	if req.wait() {
 		select {
@@ -1476,17 +1479,16 @@ exception could occur if the server does not support this method.
 
 */
 func (me *Channel) Confirm(noWait bool) error {
-	me.m.Lock()
-	defer me.m.Unlock()
-
 	if err := me.call(
 		&confirmSelect{Nowait: noWait},
 		&confirmSelectOk{},
 	); err != nil {
 		return err
 	}
 
+	me.m.Lock()
 	me.confirming = true
+	me.m.Unlock()
 
 	return nil
 }

client_test.go

@@ -601,3 +601,30 @@ func TestPublishAndShutdownDeadlockIssue84(t *testing.T) {
 		}
 	}
 }
+
+func TestChannelCloseRace(t *testing.T) {
+	rwc, srv := newSession(t)
+
+	done := make(chan bool)
+
+	go func() {
+		srv.connectionOpen()
+		srv.channelOpen(1)
+
+		rwc.Close()
+		done <- true
+	}()
+
+	c, err := Open(rwc, defaultConfig())
+	if err != nil {
+		t.Fatalf("could not create connection: %v (%s)", c, err)
+	}
+
+	ch, err := c.Channel()
+	if err != nil {
+		t.Fatalf("could not open channel: %v (%s)", ch, err)
+	}
+	<-done
+	ch.Close()
+	c.Close()
+}

connection.go

@@ -340,14 +340,18 @@ func (me *Connection) send(f frame) error {
 
 func (me *Connection) shutdown(err *Error) {
 	me.destructor.Do(func() {
+		me.m.Lock()
+		defer me.m.Unlock()
+
 		if err != nil {
 			for _, c := range me.closes {
 				c <- err
 			}
 		}
 
 		for _, ch := range me.channels {
-			me.closeChannel(ch, err)
+			ch.shutdown(err)
+			me.releaseChannel(ch.id)
 		}
 
 		if err != nil {
@@ -364,9 +368,7 @@ func (me *Connection) shutdown(err *Error) {
 			close(c)
 		}
 
-		me.m.Lock()
 		me.noNotify = true
-		me.m.Unlock()
 	})
 }
 
@@ -553,9 +555,6 @@ func (me *Connection) allocateChannel() (*Channel, error) {
 // releaseChannel removes a channel from the registry as the final part of the
 // channel lifecycle
 func (me *Connection) releaseChannel(id uint16) {
-	me.m.Lock()
-	defer me.m.Unlock()
-
 	delete(me.channels, id)
 	me.allocator.release(int(id))
 }
@@ -578,6 +577,8 @@ func (me *Connection) openChannel() (*Channel, error) {
 // this connection.
 func (me *Connection) closeChannel(ch *Channel, e *Error) {
 	ch.shutdown(e)
+	me.m.Lock()
+	defer me.m.Unlock()
 	me.releaseChannel(ch.id)
 }