From 7bf1b915649fdf8e499847836f0aedd082a7fc00 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=96=E7=95=8C?= <i@sekai.icu>
Date: Wed, 10 Jun 2026 09:23:29 +0800
Subject: [PATCH] usbip: re-probe driverless devices on linux export release
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

When the exported device was replaced underneath usbip-host (devnum
changed after a flap) or the recorded original driver was empty,
releaseExport skipped the re-bind and left the device driverless — and
the USB core never re-probes such devices, so it stayed dead until a
physical replug. Worse, the next Reconcile recorded originalDriver=""
for it, making every later release repeat the damage. Release now falls
back to usbip-host's rebind attribute (device_attach, the official
usbip unbind path) with drivers_probe as a second fallback.
---
 service/usbip/host_linux.go | 61 ++++++++++++++++++++++---------------
 1 file changed, 37 insertions(+), 24 deletions(-)

diff --git a/service/usbip/host_linux.go b/service/usbip/host_linux.go
index 4fcff99ff..7c5584777 100644
--- a/service/usbip/host_linux.go
+++ b/service/usbip/host_linux.go
@@ -559,35 +559,48 @@ func (h *linuxExportHost) releaseExport(exp *linuxExport) error {
 	if err != nil {
 		return err
 	}
-	restoreCurrentDevice, err := h.shouldRestoreCurrentDevice(exp)
-	if err != nil {
-		return err
-	}
-	if !restoreCurrentDevice {
-		h.logger.Info("removed export state for ", exp.busid)
-		return nil
-	}
-	if exp.originalDriver == "" {
-		h.logger.Info("released ", exp.busid, " from usbip-host")
-		return nil
-	}
-	err = writeSysfs(filepath.Join("/sys/bus/usb/drivers", exp.originalDriver, "bind"), exp.busid)
-	if err != nil {
-		return err
-	}
-	h.logger.Info("restored ", exp.busid, " to ", exp.originalDriver)
-	return nil
-}
-
-func (h *linuxExportHost) shouldRestoreCurrentDevice(exp *linuxExport) (bool, error) {
 	descriptor, err := readSysfsDevice(exp.busid, filepath.Join(sysBusUSBDevices, exp.busid))
 	if err != nil {
 		if os.IsNotExist(err) || isMissingUSBDeviceError(err) {
-			return false, nil
+			h.logger.Info("removed export state for ", exp.busid)
+			return nil
 		}
-		return false, E.Cause(err, "read current device ", exp.busid)
+		return E.Cause(err, "read current device ", exp.busid)
 	}
-	return exp.identity.Equal(newLinuxExportIdentity(descriptor)), nil
+	if exp.originalDriver != "" && exp.identity.Equal(newLinuxExportIdentity(descriptor)) {
+		err = writeSysfs(filepath.Join("/sys/bus/usb/drivers", exp.originalDriver, "bind"), exp.busid)
+		if err == nil {
+			h.logger.Info("restored ", exp.busid, " to ", exp.originalDriver)
+			return nil
+		}
+		h.logger.Warn("bind ", exp.busid, " back to ", exp.originalDriver, ": ", err)
+	}
+	// Device replaced while exported, original driver unknown, or the
+	// precise re-bind failed. The USB core never re-probes a driverless
+	// device on its own — without an explicit re-probe the device stays
+	// dead until physically replugged.
+	err = h.reprobeDevice(exp.busid)
+	if err != nil {
+		return E.Cause(err, "re-probe ", exp.busid)
+	}
+	h.logger.Info("released ", exp.busid, " for driver re-probe")
+	return nil
+}
+
+// reprobeDevice asks the kernel to attach a driver to a currently
+// driverless device. usbip-host's rebind attribute calls
+// device_attach — the path the official usbip unbind tool uses;
+// drivers_probe is the bus-generic fallback.
+func (h *linuxExportHost) reprobeDevice(busid string) error {
+	err := writeSysfs(filepath.Join(sysUsbipHostDriver, "rebind"), busid)
+	if err == nil {
+		return nil
+	}
+	probeErr := writeSysfs("/sys/bus/usb/drivers_probe", busid)
+	if probeErr == nil {
+		return nil
+	}
+	return E.Errors(err, probeErr)
 }
 
 func (h *linuxExportHost) newExport(descriptor sysfsDevice, managed bool, originalDriver string) *linuxExport {