From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271544AbTGQVel (ORCPT ); Thu, 17 Jul 2003 17:34:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S271550AbTGQVel (ORCPT ); Thu, 17 Jul 2003 17:34:41 -0400 Received: from fw.osdl.org ([65.172.181.6]:38101 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S271544AbTGQVei (ORCPT ); Thu, 17 Jul 2003 17:34:38 -0400 Date: Thu, 17 Jul 2003 14:49:07 -0700 From: Greg KH To: Gerd Knorr Cc: Kernel List , video4linux list Subject: Re: [RFC/PATCH] sysfs'ify video4linux Message-ID: <20030717214907.GA3255@kroah.com> References: <20030715143119.GB14133@bytesex.org> <20030715212714.GB5458@kroah.com> <20030716084448.GC27600@bytesex.org> <20030716161924.GA7406@kroah.com> <20030716202018.GC26510@bytesex.org> <20030716210800.GE2279@kroah.com> <20030717120121.GA15061@bytesex.org> <20030717145749.GA5067@kroah.com> <20030717163715.GA19258@bytesex.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030717163715.GA19258@bytesex.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 17, 2003 at 06:37:15PM +0200, Gerd Knorr wrote: > > Version (1) can be done without breaking the build, with a hack along > the lines "if (no release callback) printk(KERN_WARN please fix your > driver)", so the drivers can be fixed step-by-step afterwards. That sounds like a nice way to start. > Fixing the drivers might be non-trivial through. Some drivers are > hot-pluggable (usb cams), some drivers register more than one v4l device > (bttv wants up to three). Those drivers can't just call kfree() in the > ->release callback because there might be other references, some open > file handle for a unplugged usb cam, another not-yet unregistered > v4l device, whatever. Probably they must implement some reference > counting scheme to get that right. The very simple ones (in > drivers/media/radio for example) likely just need the kfree() moved > from the ->remove function into the new ->release() callback. I don't think it will be that bad for them. Just have them change the v4l device from being a structure included in their structure, into a pointer, and then create it before registering, and free it in the release() callback. That being said, I haven't actually looked at the code to verify that this is all that is needed :) > Version (2) needs every v4l driver touched to make it compile again. > Not sure how hard it is to fixup them. I'd guess it is pretty straigt > forward to do the conversion, it's just alot of work. I also could do > a number of other cleanups along the way. Maybe I trap into some hidden > pitfalls through, havn't looked at all the drivers in detail yet. Breaking the build is a very good thing to do at times, to ensure that stuff gets fixed properly. Users might go for a while without realizing that there really is a problem in their driver. But in the end, it's up to you... thanks, greg k-h