From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23227C282C8 for ; Wed, 23 Jan 2019 04:30:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EAE6521726 for ; Wed, 23 Jan 2019 04:30:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727089AbfAWEap (ORCPT ); Tue, 22 Jan 2019 23:30:45 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45862 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726963AbfAWEap (ORCPT ); Tue, 22 Jan 2019 23:30:45 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 551ADC05D3ED; Wed, 23 Jan 2019 04:30:44 +0000 (UTC) Received: from x1.home (ovpn-116-182.phx2.redhat.com [10.3.116.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id A15DB65F6E; Wed, 23 Jan 2019 04:30:43 +0000 (UTC) Date: Tue, 22 Jan 2019 21:30:43 -0700 From: Alex Williamson To: Alexey Kardashevskiy , Geert Uytterhoeven Cc: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, Michael Ellerman , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH kernel] vfio-pci/nvlink2: Fix ancient gcc warnings Message-ID: <20190122213043.051d7739@x1.home> In-Reply-To: <20190123040711.21759-1-aik@ozlabs.ru> References: <20190123040711.21759-1-aik@ozlabs.ru> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 23 Jan 2019 04:30:44 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Geert, The below patch comes about from the build regressions and improvements list you've sent out, but something doesn't add up that we'd be testing with an old compiler where initialization with { 0 } generates a "missing braces around initialization" warning. Is this really the case or are we missing something here? There's no harm that I can see with Alexey's fix, but are these really just false positives from a compiler bug that we should selectively ignore if the "fix" is less clean? Thanks, Alex On Wed, 23 Jan 2019 15:07:11 +1100 Alexey Kardashevskiy wrote: > Using the {0} construct as a generic initializer is perfectly fine in C, > however due to a bug in old gcc there is a warning: > > + /kisskb/src/drivers/vfio/pci/vfio_pci_nvlink2.c: warning: (near > initialization for 'cap.header') [-Wmissing-braces]: => 181:9 > > Since for whatever reason we still want to compile the modern kernel > with such an old gcc without warnings, this changes the capabilities > initialization. > > The gcc bugzilla: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53119 > > Signed-off-by: Alexey Kardashevskiy > --- > drivers/vfio/pci/vfio_pci_nvlink2.c | 30 ++++++++++++++--------------- > 1 file changed, 15 insertions(+), 15 deletions(-) > > diff --git a/drivers/vfio/pci/vfio_pci_nvlink2.c b/drivers/vfio/pci/vfio_pci_nvlink2.c > index 054a2cf..91d945b 100644 > --- a/drivers/vfio/pci/vfio_pci_nvlink2.c > +++ b/drivers/vfio/pci/vfio_pci_nvlink2.c > @@ -178,11 +178,11 @@ static int vfio_pci_nvgpu_add_capability(struct vfio_pci_device *vdev, > struct vfio_pci_region *region, struct vfio_info_cap *caps) > { > struct vfio_pci_nvgpu_data *data = region->data; > - struct vfio_region_info_cap_nvlink2_ssatgt cap = { 0 }; > - > - cap.header.id = VFIO_REGION_INFO_CAP_NVLINK2_SSATGT; > - cap.header.version = 1; > - cap.tgt = data->gpu_tgt; > + struct vfio_region_info_cap_nvlink2_ssatgt cap = { > + .header.id = VFIO_REGION_INFO_CAP_NVLINK2_SSATGT, > + .header.version = 1, > + .tgt = data->gpu_tgt > + }; > > return vfio_info_add_capability(caps, &cap.header, sizeof(cap)); > } > @@ -365,18 +365,18 @@ static int vfio_pci_npu2_add_capability(struct vfio_pci_device *vdev, > struct vfio_pci_region *region, struct vfio_info_cap *caps) > { > struct vfio_pci_npu2_data *data = region->data; > - struct vfio_region_info_cap_nvlink2_ssatgt captgt = { 0 }; > - struct vfio_region_info_cap_nvlink2_lnkspd capspd = { 0 }; > + struct vfio_region_info_cap_nvlink2_ssatgt captgt = { > + .header.id = VFIO_REGION_INFO_CAP_NVLINK2_SSATGT, > + .header.version = 1, > + .tgt = data->gpu_tgt > + }; > + struct vfio_region_info_cap_nvlink2_lnkspd capspd = { > + .header.id = VFIO_REGION_INFO_CAP_NVLINK2_LNKSPD, > + .header.version = 1, > + .link_speed = data->link_speed > + }; > int ret; > > - captgt.header.id = VFIO_REGION_INFO_CAP_NVLINK2_SSATGT; > - captgt.header.version = 1; > - captgt.tgt = data->gpu_tgt; > - > - capspd.header.id = VFIO_REGION_INFO_CAP_NVLINK2_LNKSPD; > - capspd.header.version = 1; > - capspd.link_speed = data->link_speed; > - > ret = vfio_info_add_capability(caps, &captgt.header, sizeof(captgt)); > if (ret) > return ret;