Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763659AbXJRBwT (ORCPT ); Wed, 17 Oct 2007 21:52:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757444AbXJRBwI (ORCPT ); Wed, 17 Oct 2007 21:52:08 -0400 Received: from an-out-0708.google.com ([209.85.132.243]:5309 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756454AbXJRBwE (ORCPT ); Wed, 17 Oct 2007 21:52:04 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=O+YlBNUUC2E8CyA9Hn6SoTRXgK+OGWaXAEyu+f0Xd5y7WSh1m1XM1eKLBGr15lHhA/Eby7ywGkFfxkThssJDFWA2waHo/t/8oj9CoIt6kc9QYRYgdibrwVt9S6U3OzK91kfKivzKf+tvtFYIhwD843CGYwwVWEiVpZYbotq1YeA= Message-ID: Date: Thu, 18 Oct 2007 09:52:03 +0800 From: "Dave Young" To: "Alan Stern" Subject: Re: [linux-usb-devel] usb+sysfs: duplicate filename 'bInterfaceNumber' Cc: "Matthew Dharm" , "Greg KH" , bbpetkov@yahoo.de, "Kernel development list" , "USB development list" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20071016191323.GC24082@one-eyed-alien.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3259 Lines: 83 On 10/17/07, Alan Stern wrote: > On Tue, 16 Oct 2007, Matthew Dharm wrote: > > > On Tue, Oct 16, 2007 at 02:04:43PM -0400, Alan Stern wrote: > > > On Tue, 16 Oct 2007, Matthew Dharm wrote: > > > > > > > I haven't looked at this code at all, but neither approach feels right to > > > > me. > > > > > > > > How does this work at all? Even if you load a driver later, wouldn't it > > > > call usb_set_interface(), which would call usb_create_sysfs_intf_files() > > > > and hit the same issue? > > > > > > usb_set_interface() is smart enough to remove the old interface files > > > before creating new ones, since it expects them to exist already. > > > Hence there's no problem in that scenario. > > > > > > But usb_set_configuration doesn't expect there to be any pre-existing > > > interface files, because there isn't even an interface until the > > > registration is performed. > > > > And I'm guessing that you can't call usb_create_sysfs_intf_files() until > > registration is performed, right? > > Right. > > > > The most important reason has to do with the endpoint pseudo-devices. > > > Different altsettings can have different endpoints, so those have to be > > > removed and re-created whenever the altsetting changes. > > > > Right, altsettings. I forgot about those. I only ever think in terms of > > multiple configurations. > > > > *grumble* > > > > If usb_set_interface() has to be smart enough to remove existing files > > first already, then I guess it's reasonably symmetric to have > > usb_set_configuration() have the same smarts. Maybe they can share some > > common code, even. > > It's not a big deal to remove the files first. In fact, here's a patch > to do it. Dave, see if this doesn't fix your problem. I don't like it > much because it does an unnecessary remove/create cycle, but that's > better than doing something wrong. Although it's not the best fix, the problem is fixed, Thanks. > > It's slightly odd that the sysfs core logs an error when you try to > create the same file twice but it doesn't when you try to remove a > non-existent file (or try to remove an existing file twice). Oh > well... > > Alan Stern > > > > Index: usb-2.6/drivers/usb/core/message.c > =================================================================== > --- usb-2.6.orig/drivers/usb/core/message.c > +++ usb-2.6/drivers/usb/core/message.c > @@ -1643,7 +1643,13 @@ free_interfaces: > intf->dev.bus_id, ret); > continue; > } > - usb_create_sysfs_intf_files (intf); > + > + /* The driver's probe method can call usb_set_interface(), > + * which would mean the interface's sysfs files are already > + * created. Just in case, we'll remove them first. > + */ > + usb_remove_sysfs_intf_files(intf); > + usb_create_sysfs_intf_files(intf); > } > > usb_autosuspend_device(dev); > > - 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/