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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CCD42C433EF for ; Mon, 29 Nov 2021 22:43:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234249AbhK2Wq4 (ORCPT ); Mon, 29 Nov 2021 17:46:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234338AbhK2WoT (ORCPT ); Mon, 29 Nov 2021 17:44:19 -0500 Received: from mail-yb1-xb2f.google.com (mail-yb1-xb2f.google.com [IPv6:2607:f8b0:4864:20::b2f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5C57C111CE7; Mon, 29 Nov 2021 09:39:12 -0800 (PST) Received: by mail-yb1-xb2f.google.com with SMTP id v138so44556606ybb.8; Mon, 29 Nov 2021 09:39:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=N/h+zmVfAqy959zZ9BMXX2/1A5wdWpzzXEiwOZkidAo=; b=Es/C2bASl8GHz5I7lyf6uhdpLBEaXtgpaj8Y00kQuxvSfKKHt2BGvZMwQV2KlZxfXt 0Jou8XgkBwQDdNUiNftc4seTAyOgmDc+ayN+uI6XZYb2G6tCX9V8OUyr8VG/71jfue67 oV1L3rJIzxoew96VzZ900MNBB6bO+DINhL7qC378R1LjjbhbsfNCQ+YZE8TnrBudSwJ9 2MXwoizwcCvvB4qSA3UR+QpEUqeue4FAX6JBvS1rXmvt4aq8VpJP7G/puGG051lOFTbK X3rDezDb07PEGRcpnXsPUR0KSQ9eK+AGOsw+A/Ev9BFbvPqwfXKRzdjw4S31kCVurrFK MSrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=N/h+zmVfAqy959zZ9BMXX2/1A5wdWpzzXEiwOZkidAo=; b=7KYOQFp55axLYSqORQrCFZqB8ViMSMcRsF8INiBGcK5vO2k4M3Oo3jWNJ2+lM+/yxg P8zXYG+LnPh4Aw4+sDv0jd2Jd/A5t4V/YmJdnxoxX8OKikLWG7k23JQqh1Z46Sds3S/0 YPMct2BKMYHLLnTsrIOVGp1Wl6S2tdgRUOTedaICk4dU/noX2dkoRWJCVyQp1DjrVrmY a0E7ylzODATtwDuZeILkjeLG9Tj6/nQD8gMACB7JHe+OoUDDAuURqtXaW+eb6phntLD6 RYvR2GE+vOjqmKXgDB0VBq7WcQjjLJy4pvE75NCMnvKw7PivG5TysuYOGJ5NVxu/pcyL sJWw== X-Gm-Message-State: AOAM532Zwf3326YdAo263K9oSbPofrXfO50gHVi+OgWLkW8hsHN05tDo RRzVgPFF6ZsE4cmOGdyIrLW4Ai+OmJKa8THUY55YB8P2/ZU= X-Google-Smtp-Source: ABdhPJzAb+zhz5Hk2/zQvp+Kc9uZ/wFYqmRadUzC5zH2p6qh8JLtGZLeWJejWEerR5rRbl8C/vH8QPL5tIXX6iFhjpU= X-Received: by 2002:a25:b204:: with SMTP id i4mr36682982ybj.263.1638207552001; Mon, 29 Nov 2021 09:39:12 -0800 (PST) MIME-Version: 1.0 References: <1638180040-8037-1-git-send-email-alan.maguire@oracle.com> In-Reply-To: <1638180040-8037-1-git-send-email-alan.maguire@oracle.com> From: Andrii Nakryiko Date: Mon, 29 Nov 2021 09:39:01 -0800 Message-ID: Subject: Re: [PATCH bpf] libbpf: silence uninitialized warning/error in btf_dump_dump_type_data To: Alan Maguire , Arnaldo Carvalho de Melo Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin Lau , Song Liu , Yonghong Song , john fastabend , KP Singh , Networking , bpf Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Nov 29, 2021 at 2:01 AM Alan Maguire wrot= e: > > When compiling libbpf with gcc 4.8.5, we see: > > CC staticobjs/btf_dump.o > btf_dump.c: In function =E2=80=98btf_dump_dump_type_data.isra.24=E2=80=99= : > btf_dump.c:2296:5: error: =E2=80=98err=E2=80=99 may be used uninitialized= in this function [-Werror=3Dmaybe-uninitialized] > if (err < 0) > ^ > cc1: all warnings being treated as errors > make: *** [staticobjs/btf_dump.o] Error 1 > > While gcc 4.8.5 is too old to build the upstream kernel, it's possible it > could be used to build standalone libbpf which suffers from the same prob= lem. > Silence the error by initializing 'err' to 0. The warning/error seems to= be > a false positive since err is set early in the function. Regardless we > shouldn't prevent libbpf from building for this. > > Fixes: 920d16af9b42 ("libbpf: BTF dumper support for typed data") > > Signed-off-by: Alan Maguire > --- Arnaldo also complained about this. Applied to bpf-next, I don't think it needs to be in the bpf tree. Thanks. > tools/lib/bpf/btf_dump.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c > index 17db62b..5cae716 100644 > --- a/tools/lib/bpf/btf_dump.c > +++ b/tools/lib/bpf/btf_dump.c > @@ -2194,7 +2194,7 @@ static int btf_dump_dump_type_data(struct btf_dump = *d, > __u8 bits_offset, > __u8 bit_sz) > { > - int size, err; > + int size, err =3D 0; > > size =3D btf_dump_type_data_check_overflow(d, t, id, data, bits_o= ffset); > if (size < 0) > -- > 1.8.3.1 >