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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 5C0ADC47089 for ; Fri, 28 May 2021 02:11:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 36199613BA for ; Fri, 28 May 2021 02:11:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235818AbhE1CMp (ORCPT ); Thu, 27 May 2021 22:12:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234834AbhE1CMn (ORCPT ); Thu, 27 May 2021 22:12:43 -0400 Received: from mail-ed1-x52d.google.com (mail-ed1-x52d.google.com [IPv6:2a00:1450:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE895C061574 for ; Thu, 27 May 2021 19:11:08 -0700 (PDT) Received: by mail-ed1-x52d.google.com with SMTP id i13so3042355edb.9 for ; Thu, 27 May 2021 19:11:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=riotgames.com; s=riotgames; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=dhWqc7luBqopDDE1vxw6mdGkufVV95ZXdV0JPppZwnk=; b=Gwg5a1zG/eR0L3v7/o+zaP/WtuRNlxJa3rlm1JSA/6YX1xyJNfS5urHcqCNdcpYMF3 AxbYMGqSA04CpMher0XD9WcwZSLMfBSDjiKdLmL9rLBwPi04BRJ9HFaRu9kXJimVWoX2 /Tjb8hzMH1kmF+1m7P+uAHYmmLr77FUGbloUo= 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=dhWqc7luBqopDDE1vxw6mdGkufVV95ZXdV0JPppZwnk=; b=rPV4pZMMxy9UGBr7FFtv5piWr3dOftaCyyJiD4ZEA6s3M4+5t1h6sJEJ3bo9vfMO3K bLJGfKJpN28sSL0jtIHXo1LFgVowvUrlcFeuAAAtkHbz+LU+KaDX2q8+HDhllmA2GKLl 20VeoVf/FpUzaaQJOXdaRP3m6AKeDV2r5uaMidue1Pv54jzQZtxGPldsLlVEOj0m2vs0 sW6TFyv1Q6VrcL35ETp5XuZgKVApnk6ZmdwboTOLBZy/Ajg6fWp1kpuqUqe2vqaVvNH2 is9cG3wlqfOOZ2uSKb++87dCh/rmIuw4J5k1mdzObz47KNi2hsrO/UG9AMbD2EZdOg40 KfDw== X-Gm-Message-State: AOAM532LdHnBBKUfRHRS2sg0S3NaO4TrQfipEFd2keEJ0/EUxbBtTrKR 0nohpxB2FXhtVghONB2J2A9WP09rYPaTrTk17ZqhCg== X-Google-Smtp-Source: ABdhPJz4pJQ5QXKgcpzXmDdQ92DSXOhVJq83D6HQCvzpOtsFa0DBEyijkkibhDuEA2rt71FBLqFdYHSt4Y8c7VsANMA= X-Received: by 2002:aa7:da94:: with SMTP id q20mr6250785eds.316.1622167867327; Thu, 27 May 2021 19:11:07 -0700 (PDT) MIME-Version: 1.0 References: <20210527201341.7128-1-zeffron@riotgames.com> <20210527201341.7128-4-zeffron@riotgames.com> In-Reply-To: From: Zvi Effron Date: Thu, 27 May 2021 19:10:56 -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: Andrii Nakryiko 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 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?