From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752826Ab1K3ScW (ORCPT ); Wed, 30 Nov 2011 13:32:22 -0500 Received: from moutng.kundenserver.de ([212.227.126.171]:62909 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751151Ab1K3ScS (ORCPT ); Wed, 30 Nov 2011 13:32:18 -0500 From: Arnd Bergmann To: "Michael S. Tsirkin" Subject: Re: [PATCH-RFC 1/2] tile: don't panic on iomap Date: Wed, 30 Nov 2011 18:32:11 +0000 User-Agent: KMail/1.12.2 (Linux/3.2.0-rc1+; KDE/4.3.2; x86_64; ; ) 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 References: <201111301549.57430.arnd@arndb.de> <20111130155925.GA25812@redhat.com> In-Reply-To: <20111130155925.GA25812@redhat.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201111301832.11578.arnd@arndb.de> X-Provags-ID: V02:K0:3ErVgRecTSoASJuI2FOU9S7N1AfU7WouIaXByDXJCgq Tsqu+1Piatn2TUoHBVIAS1pLlH+IK+kXHUc4cxlS5Ylqfp31Vh 40lkXa3WYM7vvk1I+XFPdf6YQY4y1sbtdLldvnPPh5jlJS9/0i A5A8kZ2OGZHKCqUCqow9116EwCGDE2A+jXte31wLqNBfGbve2a jVhFvciNSzeRX780GVPMH5X5wnqxMYLSOo3oxtkCEkv7pN4aqq emURFyNyEpLGN5I0ClvNF5s+ccd1QjXQVaaEXesJTXSa4qWo0l MARKAOdF0tmWPloJEojpn/UBm86lfZd9cC9DlVsNWOl2fPtpmD U729kIEFdGkYB2IpOzhQ= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 30 November 2011, Michael S. Tsirkin wrote: > On Wed, Nov 30, 2011 at 03:49:57PM +0000, Arnd Bergmann wrote: > > 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. > > Yes but uglifying these users is also bad, ifdefs in code are incredibly > fragile. Isn't it enough to declare ioport_map __must_check? I guess we already wasted too many electrons over this triviality, I don't actually care all that much, and will probably have to touch the same code again when I get to submit my patch to make inb/outb optional for architectures. Just pick any solution (including your original one). I'll revisit this when I'm bothered by the presence of the ioport_map function and will keep you in the loop on those patches. Arnd