Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161316AbWJLJab (ORCPT ); Thu, 12 Oct 2006 05:30:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161318AbWJLJaa (ORCPT ); Thu, 12 Oct 2006 05:30:30 -0400 Received: from mtagate4.de.ibm.com ([195.212.29.153]:12855 "EHLO mtagate4.de.ibm.com") by vger.kernel.org with ESMTP id S1161316AbWJLJa3 (ORCPT ); Thu, 12 Oct 2006 05:30:29 -0400 Date: Thu, 12 Oct 2006 11:30:47 +0200 From: Cornelia Huck To: Alan Stern Cc: Jaroslav Kysela , Andrew Morton , ALSA development , Takashi Iwai , Greg KH , LKML , Jiri Kosina , Castet Matthieu , Akinobu Mita Subject: Re: [PATCH] Driver core: Don't ignore bus_attach_device() retval Message-ID: <20061012113047.1df2a9c8@gondolin.boeblingen.de.ibm.com> In-Reply-To: References: <20061009131434.6e3ff0e2@gondolin.boeblingen.de.ibm.com> X-Mailer: Sylpheed-Claws 2.5.3 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2374 Lines: 51 On Wed, 11 Oct 2006 10:49:36 -0400 (EDT), Alan Stern wrote: > You know, I'm not so sure device registration should fail when > bus_attach_device() returns an error. Hm, let's see why bus_attach_device() might fail: * device_bind_driver() failed to create some symlinks. We may consider not to fail in this case, since sysfs_remove_link() is fine even for non-existing links. * probing failed for one possible driver with something other than -ENODEV or -ENXIO. Not sure if we really should abort in this case. We'd just end up with an unbound device, and a driver returning (for example) -ENOMEM for probing may just be a really dumb driver trying to allocate an insane amount of memory (and the next driver might just be fine). > Furthermore there are subtle problems that can arise. In effect, the > device is registered for a brief time (while the driver is probed) and > then unregistered without giving the bus subsystem a chance to prepare for > the removal. With USB this can lead to problems; if the driver called > usb_set_interface() then child devices would be created below the one > being probed -- and they would never get removed. One way to fix this would be to make device_bind_driver() always succeed (even without symlinks), the other to call the ->remove function if device_bind_driver() fails (assuming that the ->remove method should undo the stuff done in ->probe). > In fact, we might want to separate driver probing from device_add() > entirely. That is, make them available as two separate function calls. > That way the subsystem driver will have a chance to create attribute files > before a uevent is generated and a driver is loaded. (That should help > udev to work better.) This would require a larger change, though -- > probably requiring an alternate version of device_add(). Shouldn't subsystems that need attributes early just use dev->groups, class->dev_attrs or bus->dev_attrs? These attribute groups are added before the uevent is generated. -- Cornelia Huck Linux for zSeries Developer Tel.: +49-7031-16-4837, Mail: cornelia.huck@de.ibm.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/