USB: Fix device driver race

When a new device with a specialised device driver is plugged in, the
new driver will be modprobe()'d but the driver core will attach the
"generic" driver to the device.

After that, nothing will trigger a reprobe when the modprobe()'d device
driver has finished initialising, as the device has the "generic"
driver attached to it.

Trigger a reprobe ourselves when new specialised drivers get registered.

Fixes: 88b7381a939d ("USB: Select better matching USB drivers when available")
Signed-off-by: Bastien Nocera <hadess@hadess.net>
Cc: stable <stable@vger.kernel.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20200818110445.509668-3-hadess@hadess.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index f81606c..7e73e98 100644 (file)
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -905,6 +905,35 @@ static int usb_uevent(struct device *dev, struct kobj_uevent_env *env)
        return 0;
 }
 
+static bool is_dev_usb_generic_driver(struct device *dev)
+{
+       struct usb_device_driver *udd = dev->driver ?
+               to_usb_device_driver(dev->driver) : NULL;
+
+       return udd == &usb_generic_driver;
+}
+
+static int __usb_bus_reprobe_drivers(struct device *dev, void *data)
+{
+       struct usb_device_driver *new_udriver = data;
+       struct usb_device *udev;
+       int ret;
+
+       if (!is_dev_usb_generic_driver(dev))
+               return 0;
+
+       udev = to_usb_device(dev);
+       if (usb_device_match_id(udev, new_udriver->id_table) == NULL &&
+           (!new_udriver->match || new_udriver->match(udev) != 0))
+               return 0;
+
+       ret = device_reprobe(dev);
+       if (ret && ret != -EPROBE_DEFER)
+               dev_err(dev, "Failed to reprobe device (error %d)\n", ret);
+
+       return 0;
+}
+
 /**
  * usb_register_device_driver - register a USB device (not interface) driver
  * @new_udriver: USB operations for the device driver
@@ -934,13 +963,20 @@ int usb_register_device_driver(struct usb_device_driver *new_udriver,
 
        retval = driver_register(&new_udriver->drvwrap.driver);
 
-       if (!retval)
+       if (!retval) {
                pr_info("%s: registered new device driver %s\n",
                        usbcore_name, new_udriver->name);
-       else
+               /*
+                * Check whether any device could be better served with
+                * this new driver
+                */
+               bus_for_each_dev(&usb_bus_type, NULL, new_udriver,
+                                __usb_bus_reprobe_drivers);
+       } else {
                printk(KERN_ERR "%s: error %d registering device "
                        "       driver %s\n",
                        usbcore_name, retval, new_udriver->name);
+       }
 
        return retval;
 }