This is a note to let you know that I've just added the patch titled

USB: Fix device driver race

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From d5643d2249b279077427b2c2b2ffae9b70c95b0b Mon Sep 17 00:00:00 2001

From: Bastien Nocera hadess@hadess.net Date: Tue, 18 Aug 2020 13:04:45 +0200 Subject: 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 --- drivers/usb/core/driver.c | 40 +++++++++++++++++++++++++++++++++++++-- 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c index f81606c6a35b..7e73e989645b 100644 --- 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; }