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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,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 C00B6C2BA17 for ; Mon, 6 Apr 2020 02:46:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 878AC206F7 for ; Mon, 6 Apr 2020 02:46:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="WkVVGgWF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726436AbgDFCqv (ORCPT ); Sun, 5 Apr 2020 22:46:51 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:45039 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726408AbgDFCqu (ORCPT ); Sun, 5 Apr 2020 22:46:50 -0400 Received: by mail-qk1-f194.google.com with SMTP id j4so14739008qkc.11; Sun, 05 Apr 2020 19:46:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=56voqtFYeudq/VV/J/Sg075FrS52rvV+pYrlJWqB8HY=; b=WkVVGgWFJTYzEXNm/LIEDG1GuUzpOrz4DjCrAvs6wKize+qZNPWC8LlXA/6BG2CCeQ SJ9N1/YOs7HN1KAK8sDPTBaKUzmpGzvdiiIy7o/0MJsi7LkA+3TtqJa/tNCOztOMcBsK 3S/8r7YXulhYeSCnqYYPCPbyhbCLgBGMa1b3XMGqI3yIqkBAPfQwpnGI/WMf7WUguVf3 GCwBj4gNVCmUMijdwtz3UtUGPH55hLfUtJshRftvHkKkW5krkt3w4OK8x2dkBtDsUKj5 /QP8/9hCmdMu8DaDDqtYiFq1YJA1pxs2KacuBdZCzo9jogRc2h0gA0/MG5LxNF6/4ujg uaZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=56voqtFYeudq/VV/J/Sg075FrS52rvV+pYrlJWqB8HY=; b=JuntiiMeWgfxxcdlFbLTMWYM2jzwOu732HEhVuQh7jpmkv08HOr1UaWMDpFl46/35i iiLeyL37Ipr9JtdmwqqWxMvlsHD3bkLsx8TTY0T71Qt3vHvxtj9b0UBoRcqO+SVhZgpA V24Tcz8NuDh82KKeOScuONyHOOQejV1Q4kSCTWduFcTd+y1R2OUBkHTTDseI1K27LDZ9 h6AUWn4iyEcFwIJJI0+Va012Qnqj1vMELxBh+mN3NngaktkRFMS/SWse3eZAE/KeNkaG OEs/fNEZ04tfBUb/x5Q/2bIdYp1APH+K61m7M+/kMO9sica1GwE8aMKIEHq815VYaKII Xxag== X-Gm-Message-State: AGi0PuaQpL2LAypLb3KQ7pp1J+TvK75eBXyVCPVPTB8KytZv1G7wzuCw aZAjA1Qkf3amfoLusEem14x/EeU3OTD9r788dIk= X-Google-Smtp-Source: APiQypLFRORlr4Vh0aYKObYp4Acq9iJezPZdOKLsC++BIczCfPtmRtzIkM7pLbLgyrnkXclrZIDRaUte9iHcVg1wXdc= X-Received: by 2002:a05:620a:88e:: with SMTP id b14mr20514490qka.449.1586141209712; Sun, 05 Apr 2020 19:46:49 -0700 (PDT) MIME-Version: 1.0 References: <20200404051430.698058-1-jcline@redhat.com> In-Reply-To: <20200404051430.698058-1-jcline@redhat.com> From: Andrii Nakryiko Date: Sun, 5 Apr 2020 19:46:38 -0700 Message-ID: Subject: Re: [PATCH] libbpf: Initialize *nl_pid so gcc 10 is happy To: Jeremy Cline Cc: Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , "David S . Miller" , Jakub Kicinski , Jesper Dangaard Brouer , Networking , bpf , open list Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Apr 3, 2020 at 10:15 PM Jeremy Cline wrote: > > Builds of Fedora's kernel-tools package started to fail with "may be > used uninitialized" warnings for nl_pid in bpf_set_link_xdp_fd() and > bpf_get_link_xdp_info() on the s390 architecture. > > Although libbpf_netlink_open() always returns a negative number when it > does not set *nl_pid, the compiler does not determine this and thus > believes the variable might be used uninitialized. Assuage gcc's fears > by explicitly initializing nl_pid. > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1807781 > Signed-off-by: Jeremy Cline > --- Yep, unfortunately compiler is not that smart. Acked-by: Andrii Nakryiko > tools/lib/bpf/netlink.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c > index 18b5319025e19..9a14694176de0 100644 > --- a/tools/lib/bpf/netlink.c > +++ b/tools/lib/bpf/netlink.c > @@ -142,7 +142,7 @@ static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd, > struct ifinfomsg ifinfo; > char attrbuf[64]; > } req; > - __u32 nl_pid; > + __u32 nl_pid = 0; > > sock = libbpf_netlink_open(&nl_pid); > if (sock < 0) > @@ -288,7 +288,7 @@ int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info, > { > struct xdp_id_md xdp_id = {}; > int sock, ret; > - __u32 nl_pid; > + __u32 nl_pid = 0; > __u32 mask; > > if (flags & ~XDP_FLAGS_MASK || !info_size) > -- > 2.26.0 >