Merge pull request #4 from rigado/fix/race_on_disconnect

Fix race condition on disconnect

linux/hci/conn.go

@@ -195,6 +195,15 @@ func (c *Conn) writePDU(pdu []byte) (int, error) {
 	c.txBuffer.LockPool()
 	defer c.txBuffer.UnlockPool()
 
+	// Fail immediately if the connection is already closed
+	// Check this with the pool locked to avoid race conditions
+	// with handleDisconnectionComplete
+	select {
+	case <-c.chDone:
+		return 0, io.ErrClosedPipe
+	default:
+	}
+
 	for len(pdu) > 0 {
 		// Get a buffer from our pre-allocated and flow-controlled pool.
 		pkt := c.txBuffer.Get() // ACL pkt

linux/hci/hci.go

@@ -513,7 +513,13 @@ func (h *HCI) handleDisconnectionComplete(b []byte) error {
 	}
 	// When a connection disconnects, all the sent packets and weren't acked yet
 	// will be recycled. [Vol2, Part E 4.1.1]
+	//
+	// must be done with the pool locked to avoid race conditions where
+	// writePDU is in progress and does a Get from the pool after this completes,
+	// leaking a buffer from the main pool.
+	c.txBuffer.LockPool()
 	c.txBuffer.PutAll()
+	c.txBuffer.UnlockPool()
 	return nil
 }