fix driver rebinding

internal/client/share.go

@@ -276,17 +276,28 @@ func (sm *ShareManager) handleReleaseDevice(busID, fromClient string) {
 		return
 	}
 
-	// Clean up tunnel
+	// Close the tunnel pipe to signal HandleConnection to stop reading
+	var tunnelDone <-chan struct{}
 	if tunnel, ok := sm.tunnels[share.tunnelID]; ok {
 		tunnel.inPipe.Close()
+		tunnelDone = tunnel.done
 		delete(sm.tunnels, share.tunnelID)
 	}
 
-	// Detach device (release interfaces, reconnect kernel driver)
-	share.server.Detach()
+	server := share.server
 	delete(sm.active, busID)
 	sm.mu.Unlock()
 
+	// Wait for HandleConnection goroutine to finish before detaching.
+	// This ensures no more URBs are being submitted when we detach.
+	if tunnelDone != nil {
+		<-tunnelDone
+		log.Printf("[share] HandleConnection goroutine finished for %s", busID)
+	}
+
+	// Now safe to detach - no more USB/IP protocol processing
+	server.Detach()
+
 	// Notify client
 	sm.client.SendJSON(&protocol.DeviceReleased{
 		Type:  protocol.MsgDeviceReleased,

internal/usbip/server.go

@@ -8,7 +8,10 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"os"
+	"path/filepath"
 	"sync"
+	"time"
 	"unsafe"
 
 	"github.com/duffy/usb-server/internal/usb"
@@ -95,7 +98,7 @@ func (s *Server) Attach() error {
 	return nil
 }
 
-// Detach releases all interfaces, reconnects kernel driver, and closes the device
+// Detach releases all interfaces, closes the device, and rebinds kernel drivers.
 func (s *Server) Detach() {
 	s.mu.Lock()
 	s.closed = true
@@ -124,25 +127,60 @@ func (s *Server) Detach() {
 		}
 	}
 
-	// 3. Reset device to force driver re-probing (most reliable method)
-	// A USB reset forces the kernel to re-enumerate and rebind drivers.
-	// This is important for devices like webcams that may be left in a
-	// streaming state after URB transfers.
-	if err := s.handle.ResetDevice(); err != nil {
-		log.Printf("[usbip-server] device reset failed: %v, trying ConnectDriver", err)
-		// Fallback: try to reconnect kernel driver without reset
-		if err := s.handle.ConnectDriver(); err != nil {
-			log.Printf("[usbip-server] ConnectDriver also failed: %v", err)
-		} else {
-			log.Printf("[usbip-server] kernel driver reconnected via ConnectDriver")
-		}
-	} else {
-		log.Printf("[usbip-server] device reset OK, kernel drivers re-bound")
-	}
-
-	// 4. Close the device file descriptor
+	// 3. Close the device file descriptor.
+	// The kernel auto-cancels remaining URBs on close.
 	s.handle.Close()
 	s.handle = nil
+
+	// 4. Force kernel driver re-binding via sysfs authorized toggle.
+	// After USBDEVFS_DISCONNECT_CLAIM, the kernel sets privileges_dropped=true.
+	// This means closing the fd does NOT auto-rebind drivers.
+	// Also USBDEVFS_RESET after ReleaseInterface doesn't rebind because
+	// the kernel sets needs_binding=false on release.
+	// The reliable solution: toggle authorized 0->1 which forces complete
+	// re-enumeration and driver binding.
+	s.rebindDrivers()
+}
+
+// rebindDrivers forces the kernel to re-bind drivers to the device
+// by toggling the sysfs authorized attribute.
+func (s *Server) rebindDrivers() {
+	authPath := filepath.Join(s.device.SysPath, "authorized")
+
+	// Deauthorize: kernel disconnects device, unbinds all drivers
+	if err := os.WriteFile(authPath, []byte("0"), 0644); err != nil {
+		log.Printf("[usbip-server] sysfs deauthorize failed: %v, trying fallback", err)
+		s.rebindDriversFallback()
+		return
+	}
+
+	// Brief delay for the kernel to process the deauthorization
+	time.Sleep(100 * time.Millisecond)
+
+	// Re-authorize: kernel re-enumerates device, binds drivers
+	if err := os.WriteFile(authPath, []byte("1"), 0644); err != nil {
+		log.Printf("[usbip-server] sysfs re-authorize failed: %v", err)
+		return
+	}
+
+	log.Printf("[usbip-server] device re-authorized, kernel drivers re-bound")
+}
+
+// rebindDriversFallback tries alternative methods to rebind drivers
+func (s *Server) rebindDriversFallback() {
+	// Try writing bus_id to each original driver's bind file
+	for _, iface := range s.device.Interfaces {
+		if iface.Driver == "" {
+			continue
+		}
+		ifaceName := fmt.Sprintf("%s:%d.%d", s.device.BusID, s.device.ConfigValue, iface.Number)
+		bindPath := filepath.Join("/sys/bus/usb/drivers", iface.Driver, "bind")
+		if err := os.WriteFile(bindPath, []byte(ifaceName), 0644); err != nil {
+			log.Printf("[usbip-server] bind %s to %s failed: %v", ifaceName, iface.Driver, err)
+		} else {
+			log.Printf("[usbip-server] re-bound %s to driver %s", ifaceName, iface.Driver)
+		}
+	}
 }
 
 // buildEndpointTypeMap builds the endpoint number -> URB type map from device descriptors
@@ -504,9 +542,11 @@ func (s *Server) reapLoop(retChan chan<- []byte, done <-chan struct{}) {
 			s.mu.Unlock()
 			return
 		}
+		// Save handle reference under lock to prevent nil deref race
+		handle := s.handle
 		s.mu.Unlock()
 
-		urbInfo, err := s.handle.ReapURBInfo()
+		urbInfo, err := handle.ReapURBInfo()
 		if err != nil {
 			select {
 			case <-done: