From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756363AbZCFUUh (ORCPT ); Fri, 6 Mar 2009 15:20:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754396AbZCFUU0 (ORCPT ); Fri, 6 Mar 2009 15:20:26 -0500 Received: from palinux.external.hp.com ([192.25.206.14]:54484 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752289AbZCFUU0 (ORCPT ); Fri, 6 Mar 2009 15:20:26 -0500 Date: Fri, 6 Mar 2009 13:20:24 -0700 From: Matthew Wilcox To: Yu Zhao Cc: jbarnes@virtuousgeek.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v10 3/7] PCI: reserve bus range for SR-IOV device Message-ID: <20090306202024.GF25995@parisc-linux.org> References: <1235112888-9524-1-git-send-email-yu.zhao@intel.com> <1235112888-9524-4-git-send-email-yu.zhao@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1235112888-9524-4-git-send-email-yu.zhao@intel.com> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 20, 2009 at 02:54:44PM +0800, Yu Zhao wrote: > +static inline void virtfn_bdf(struct pci_dev *dev, int id, u8 *busnr, u8 *devfn) > +{ > + u16 bdf; > + > + bdf = (dev->bus->number << 8) + dev->devfn + > + dev->sriov->offset + dev->sriov->stride * id; > + *busnr = bdf >> 8; > + *devfn = bdf & 0xff; > +} I find the interface here a bit clunky -- a function returning void while having two OUT parameters. How about this variation on the theme (viewers are encouraged to come up with their own preferred implementations and interfaces): static inline __pure u16 virtfn_bdf(struct pci_dev *dev, int id) { return (dev->bus->number << 8) + dev->devfn + dev->sriov->offset + dev->sriov->stride * id; } #define VIRT_BUS(dev, id) (virtfn_bdf(dev, id) >> 8) #define VIRT_DEVFN(dev, id) (virtfn_bdf(dev, id) & 0xff) We rely on GCC to do CSE and not actually invoke virtfn_bdf more than once. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."