From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH-RFC 1/2] tile: don't panic on iomap Date: Wed, 30 Nov 2011 15:49:57 +0000 Message-ID: <201111301549.57430.arnd@arndb.de> References: <201111301404.41544.arnd@arndb.de> <20111130143122.GC21413@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.187]:60335 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754360Ab1K3PuM (ORCPT ); Wed, 30 Nov 2011 10:50:12 -0500 In-Reply-To: <20111130143122.GC21413@redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: "Michael S. Tsirkin" Cc: Chris Metcalf , Lucas De Marchi , Paul Mundt , Jesse Barnes , "David S. Miller" , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-arch@vger.kernel.org, Andrew Morton On Wednesday 30 November 2011, Michael S. Tsirkin wrote: > On Wed, Nov 30, 2011 at 02:04:41PM +0000, Arnd Bergmann wrote: > > > Ah, right. I didn't realize that the generic pci_iomap still attempts > > to call ioport_map(). It would probably make sense to enclose > > the ioport_map() call in pci_iomap() inside of #ifdef CONFIG_HAS_IOPORT. > > It's not exactly beautiful, but probably the most correct solution > > so that we can make any call to ioport_map() a build-time error on > > architectures that set CONFIG_NO_IOPORT. > > I'm not sure why do you want to do that. > The problem is that any definition of ioport_map on architectures that can't do it is potentially harmful. Calling panic() is bad style as you pointed out, but simply returning NULL can also be harmful because it's likely that some drivers are written under the (false) assumption that ioport_map can never fail. Getting a build-time error would be more helpful here IMHO. Arnd