fix detach function with usb reset

internal/usbip/server.go

@@ -105,14 +105,42 @@ func (s *Server) Detach() {
 		return
 	}
 
-	// Release all interfaces
+	// 1. Discard all pending URBs to clean up device state
+	s.mu.Lock()
+	for seqNum, pending := range s.pendingURBs {
+		if pending.urbPtr != nil {
+			unix.Syscall(unix.SYS_IOCTL, uintptr(s.handle.Fd()),
+				0x8000550B, // USBDEVFS_DISCARDURB
+				uintptr(pending.urbPtr))
+		}
+		delete(s.pendingURBs, seqNum)
+	}
+	s.mu.Unlock()
+
+	// 2. Release all claimed interfaces
 	for _, iface := range s.device.Interfaces {
-		s.handle.ReleaseInterface(uint32(iface.Number))
+		if err := s.handle.ReleaseInterface(uint32(iface.Number)); err != nil {
+			log.Printf("[usbip-server] release interface %d: %v", iface.Number, err)
+		}
 	}
 
-	// Reconnect kernel driver
-	s.handle.ConnectDriver()
+	// 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
 	s.handle.Close()
 	s.handle = nil
 }