Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750731AbVJCKEk (ORCPT ); Mon, 3 Oct 2005 06:04:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750792AbVJCKEk (ORCPT ); Mon, 3 Oct 2005 06:04:40 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:40719 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S1750731AbVJCKEk (ORCPT ); Mon, 3 Oct 2005 06:04:40 -0400 Date: Mon, 3 Oct 2005 11:04:31 +0100 From: Russell King To: Jesper Juhl Cc: Ben Dooks , "Randy.Dunlap" , linux-kernel@vger.kernel.org Subject: Re: [PATCH] release_resource() check for NULL resource Message-ID: <20051003100431.GA16717@flint.arm.linux.org.uk> Mail-Followup-To: Jesper Juhl , Ben Dooks , "Randy.Dunlap" , linux-kernel@vger.kernel.org References: <20051002170318.GA22074@home.fluff.org> <20051002103922.34dd287d.rdunlap@xenotime.net> <20051003094803.GC3500@home.fluff.org> <9a8748490510030259o43646cbbo22b37f1791d267e@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9a8748490510030259o43646cbbo22b37f1791d267e@mail.gmail.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1724 Lines: 40 On Mon, Oct 03, 2005 at 11:59:01AM +0200, Jesper Juhl wrote: > On 10/3/05, Ben Dooks wrote: > > On Sun, Oct 02, 2005 at 10:39:22AM -0700, Randy.Dunlap wrote: > > > On Sun, 2 Oct 2005 18:03:18 +0100 Ben Dooks wrote: > > > > > > > If release_resource() is passed a NULL resource > > > > the kernel will OOPS. > > > > > > does this actually happen? you are fixing a real oops? > > > if so, what driver caused it? > > > > I was developing a couple of new drivers, and found > > that this does not behave like kfree() which does check > > for NULL paramemters. I belive it would be helpful if > > functions like this followed the example of kfree(). > > > I would agree that it makes sense for resource release functions to be > written defensively and be able to cope with being passed a NULL > resource, just like kfree(), vfree(), crypto_free_tfm() and others are > already doing. > Seems safer and allows us to get rid of checks for NULL before calling > such functions thus making code simpler, more readable and in some > cases smaller. I'm not convinced - release_resource() isn't like kfree() - it's more like device_unregister(). It makes sense for kfree() to ignore NULL pointers, but does it really make sense for *_unregister() to do so too? Surely you want to only unregister things which you know have previously been registered? -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - 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/