Exiting the middle device works now?

device/middle_device.go

@@ -163,6 +163,13 @@ func (d *MiddleDevice) pump(dev *closeAwareDevice) {
 	batchSize := dev.BatchSize()
 	logger.Debug("MiddleDevice: pump started for device")
 
+	// Recover from panic if readCh is closed while we're trying to send
+	defer func() {
+		if r := recover(); r != nil {
+			logger.Debug("MiddleDevice: pump recovered from panic (channel closed)")
+		}
+	}()
+
 	for {
 		// Check if this device is closed
 		if dev.IsClosed() {
@@ -197,7 +204,12 @@ func (d *MiddleDevice) pump(dev *closeAwareDevice) {
 			return
 		}
 
-		// Try to send the result
+		// Try to send the result - check closed state first to avoid sending on closed channel
+		if d.closed.Load() {
+			logger.Debug("MiddleDevice: pump exiting, device closed before send")
+			return
+		}
+
 		select {
 		case d.readCh <- readResult{bufs: bufs, sizes: sizes, offset: defaultOffset, n: n, err: err}:
 		default:
@@ -225,6 +237,13 @@ func (d *MiddleDevice) InjectOutbound(packet []byte) {
 	if d.closed.Load() {
 		return
 	}
+	// Use defer/recover to handle panic from sending on closed channel
+	// This can happen during shutdown race conditions
+	defer func() {
+		if r := recover(); r != nil {
+			logger.Debug("MiddleDevice: InjectOutbound recovered from panic (channel closed)")
+		}
+	}()
 	select {
 	case d.injectCh <- packet:
 	default:
@@ -268,6 +287,8 @@ func (d *MiddleDevice) Close() error {
 	d.cond.Broadcast()
 	d.mu.Unlock()
 
+	// Close underlying devices first - this causes the pump goroutines to exit
+	// when their read operations return errors
 	var lastErr error
 	logger.Debug("MiddleDevice: Closing %d devices", len(devices))
 	for _, device := range devices {
@@ -277,7 +298,12 @@ func (d *MiddleDevice) Close() error {
 		}
 	}
 
+	// Now close channels to unblock any remaining readers
+	// The pump should have exited by now, but close channels to be safe
+	close(d.readCh)
+	close(d.injectCh)
 	close(d.events)
+
 	return lastErr
 }
 
@@ -416,7 +442,11 @@ func (d *MiddleDevice) Read(bufs [][]byte, sizes []int, offset int) (n int, err
 
 		// Now block waiting for data from readCh or injectCh
 		select {
-		case res := <-d.readCh:
+		case res, ok := <-d.readCh:
+			if !ok {
+				// Channel closed, device is shutting down
+				return 0, io.EOF
+			}
 			if res.err != nil {
 				// Check if device was swapped
 				if dev.IsClosed() {
@@ -446,7 +476,11 @@ func (d *MiddleDevice) Read(bufs [][]byte, sizes []int, offset int) (n int, err
 			}
 			n = count
 
-		case pkt := <-d.injectCh:
+		case pkt, ok := <-d.injectCh:
+			if !ok {
+				// Channel closed, device is shutting down
+				return 0, io.EOF
+			}
 			if len(bufs) == 0 {
 				return 0, nil
 			}