From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:1408 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754754Ab3G2Use (ORCPT ); Mon, 29 Jul 2013 16:48:34 -0400 Message-ID: <51F6D519.3010506@redhat.com> Date: Mon, 29 Jul 2013 16:48:25 -0400 From: Don Dutile MIME-Version: 1.0 To: Alexander Duyck CC: Stefan Assmann , linux-pci@vger.kernel.org, bhelgaas@google.com, yu.zhao@intel.com Subject: Re: return value for "if (!dev->is_physfn)" References: <51F24788.6010505@kpanic.de> <51F2A735.2010405@intel.com> In-Reply-To: <51F2A735.2010405@intel.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: On 07/26/2013 12:43 PM, Alexander Duyck wrote: > On 07/26/2013 02:55 AM, Stefan Assmann wrote: >> Looking at drivers/pci/iov.c I see at least 3 different return values >> for if (!dev->is_physfn). >> >> sriov_enable() and pci_enable_sriov() >> [...] >> if (!dev->is_physfn) >> return -ENODEV; >> pci_num_vf() and pci_vfs_assigned() >> [...] >> if (!dev->is_physfn) >> return 0; >> pci_sriov_set_totalvfs() and pci_sriov_get_totalvfs() >> [...] >> if (!dev->is_physfn) >> return -EINVAL; >> >> I'd like to make this consistently return one of the above. Question is, >> which one should it be? I'd lean towards -ENODEV, other opinions? >> >> Stefan > > It all depends on how the results are meant to be interpreted. > > In the case of pci_num_vf and pci_vfs_assigned the return of 0 is > preferred since there are no VFs if the device is not a physical > function. I really think pci_sriov_get_totalvfs should probably just > return 0 as well since it is simply supposed to return the total number > of VFs supported on the device and 0 would be valid in this case. Also > that way the behavior is consistent if CONFIG_PCI_IOV is enabled or > disabled in the kernel. > +1. returning enosys hangs the caller (echo/cat of sysfs) IIRC. > As for the rest my preference is ENOSYS rather than EINVAL or ENODEV. > The issue is that the SR-IOV functionality is not implemented for the > device or in the OS when we return the error so it would make sense to > return that as an error code in these cases. > > Thanks, > > Alex > +1 > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html