From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 61240C433E5 for ; Wed, 22 Jul 2020 15:26:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F4482071A for ; Wed, 22 Jul 2020 15:26:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732648AbgGVP0l (ORCPT ); Wed, 22 Jul 2020 11:26:41 -0400 Received: from netrider.rowland.org ([192.131.102.5]:57153 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1728812AbgGVP0l (ORCPT ); Wed, 22 Jul 2020 11:26:41 -0400 Received: (qmail 1315600 invoked by uid 1000); 22 Jul 2020 11:26:40 -0400 Date: Wed, 22 Jul 2020 11:26:40 -0400 From: Alan Stern To: Bastien Nocera Cc: linux-usb@vger.kernel.org, Greg Kroah-Hartman Subject: Re: [PATCH 1/2] USB: Fix device driver race Message-ID: <20200722152640.GC1310843@rowland.harvard.edu> References: <20200722094628.4236-1-hadess@hadess.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200722094628.4236-1-hadess@hadess.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Wed, Jul 22, 2020 at 11:46:27AM +0200, Bastien Nocera wrote: > 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. > > Signed-off-by: Bastien Nocera > --- > drivers/usb/core/driver.c | 31 +++++++++++++++++++++++++++++-- > 1 file changed, 29 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c > index f81606c6a35b..a6187dd2186c 100644 > --- a/drivers/usb/core/driver.c > +++ b/drivers/usb/core/driver.c > @@ -905,6 +905,30 @@ static int usb_uevent(struct device *dev, struct kobj_uevent_env *env) > return 0; > } > > +static int __usb_bus_reprobe_drivers(struct device *dev, void *data) > +{ > + struct usb_device_driver *udriver = to_usb_device_driver(dev->driver); > + struct usb_device *udev = to_usb_device(dev); > + > + if (udriver == &usb_generic_driver && > + !udev->use_generic_driver) > + return device_reprobe(dev); > + > + return 0; > +} > + > +static int __usb_device_driver_added(struct device_driver *drv, void *data) > +{ > + struct usb_device_driver *udrv = to_usb_device_driver(drv); > + > + if (udrv->match) { > + bus_for_each_dev(&usb_bus_type, NULL, udrv, > + __usb_bus_reprobe_drivers); What does udrv get used for here? > + } > + > + return 0; > +} > + > /** > * usb_register_device_driver - register a USB device (not interface) driver > * @new_udriver: USB operations for the device driver > @@ -934,13 +958,16 @@ int usb_register_device_driver(struct usb_device_driver *new_udriver, > > retval = driver_register(&new_udriver->drvwrap.driver); > > - if (!retval) > + if (!retval) { > + bus_for_each_drv(&usb_bus_type, NULL, NULL, > + __usb_device_driver_added); This looks funny. You're calling both bus_for_each_drv() and bus_for_each_dev(). Can't you skip this iterator and just call bus_for_each_dev() directly? Alan Stern