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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 D4E50C47089 for ; Fri, 28 May 2021 03:22:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A68B66113E for ; Fri, 28 May 2021 03:22:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234781AbhE1DXh (ORCPT ); Thu, 27 May 2021 23:23:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234628AbhE1DXh (ORCPT ); Thu, 27 May 2021 23:23:37 -0400 Received: from mail-yb1-xb32.google.com (mail-yb1-xb32.google.com [IPv6:2607:f8b0:4864:20::b32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DE1EC061574 for ; Thu, 27 May 2021 20:22:03 -0700 (PDT) Received: by mail-yb1-xb32.google.com with SMTP id f9so3621564ybo.6 for ; Thu, 27 May 2021 20:22:03 -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=kpSO3wak9pYbjU8bVRU1mx3RmZJ6cjV0xgjWhYreMhU=; b=QPIQ8CvxxmEvIIBUsdW6hXnK5PoAPdgENGNDIBG0JZD494qsCc9/qmN2ew/ieXx0mO hKh8mG9r2hkzj8svdeslXdn+KbRON7BMldkgDu5Iuo/p4VRXtDbhlHP1Y9h6s1Wqtmhz MzDDxQ1GsqAapG7F0yVd5nFkI6/Xx6drQLzsqagWtJKiOIQM3Ubh6liNb79596ouP705 LxeidZ8fIhUwKYtRNSMw6pI4orpgr5GLimJglZrv0uKU6qARN2BKrFm60ECxZyXfC4Xm YvLV7yqZwxowk3XwaoC5EA8H/5is5zv0ydNkPZSvYYOhWKhEcbFSVA2hnyfZrkKL5g9t 8g7A== 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=kpSO3wak9pYbjU8bVRU1mx3RmZJ6cjV0xgjWhYreMhU=; b=Fu678C8FPnTjAa5Xssz9OTw67SjgSoU7WztNg2l8zEHr0BP0hitRbczKCMSqLtFyw0 YhFXhD4tIme7Mv2P1Z0WJRhOdqI3ldF7gFcAFmne5v7Cr07oIwGpJ8VWgzbMSRg3tG2/ VFX8hWJGMTb9uAHOx8hEmbAFTBjReoxn55NvorZQls9eRhCVZxpklb/yu2RFkh4kgW5/ ANRI4ACMUbAY/+eeit17IZAcoM/3j4MEpf4ghhCaMUJdh4Jz5L+TA0eREs264cwAHEZF kFJzHArAbbZDX3XtbYHgvogNIuLEXhl8SAItKgO+xCo9qBGyNa2HtsLddnZRCZqXekWs k8dw== X-Gm-Message-State: AOAM530QqvPJytXTDhhCEnoAp1eVWxJXDNN2MfRMyiNSuc200iNpeLXT G1svOogh5PSmiKtTbdd2bAyMapW1AahGLdD/kIM= X-Google-Smtp-Source: ABdhPJzBOI2LFzQa6pIGPRUk2nYhCbgkmQJvi+ohw5HzCriawKhc0PM0dS2EUAN8I6ciQZ/1gNsU4tfINMuZOMAmMG4= X-Received: by 2002:a5b:f05:: with SMTP id x5mr9225881ybr.425.1622172122504; Thu, 27 May 2021 20:22:02 -0700 (PDT) MIME-Version: 1.0 References: <20210527201341.7128-1-zeffron@riotgames.com> <20210527201341.7128-4-zeffron@riotgames.com> In-Reply-To: From: Andrii Nakryiko Date: Thu, 27 May 2021 20:21:51 -0700 Message-ID: Subject: Re: [PATCH bpf-next v2 3/3] selftests/bpf: Add test for xdp_md context in BPF_PROG_TEST_RUN To: Zvi Effron Cc: bpf , Alexei Starovoitov , "David S. Miller" , Daniel Borkmann , Jesper Dangaard Brouer , Cody Haas , Lisa Watanabe Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, May 27, 2021 at 7:11 PM Zvi Effron wrote: > > On Thu, May 27, 2021 at 6:28 PM Andrii Nakryiko > wrote: > > > > On Thu, May 27, 2021 at 1:14 PM Zvi Effron wrote: > > > > > > + > > > + /* Data past the end of the kernel's struct xdp_md must be 0 */ > > > + bad_ctx[sizeof(bad_ctx) - 1] = 1; > > > + tattr.ctx_in = bad_ctx; > > > + tattr.ctx_size_in = sizeof(bad_ctx); > > > + err = bpf_prog_test_run_opts(prog_fd, &tattr); > > > + ASSERT_ERR(err, "bpf_prog_test_run(test2)"); > > > + ASSERT_EQ(errno, 22, "test2-errno"); > > > > by the time you are checking errno it might get overwritten. If you > > want to check errno, you have to remember it right after the function > > returns > > Is it sufficient to simply make the errno ASSERT the first thing after > the function returns? Or would we still need to preserve it into a > local variable? Yes, doing ASSERT_EQ(errno, 22, "test2-errno") right after bpf_prog_test_run_opts() will work reliably.