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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 2DABAC433ED for ; Thu, 22 Apr 2021 03:32:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 047BB61450 for ; Thu, 22 Apr 2021 03:32:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234637AbhDVDdA (ORCPT ); Wed, 21 Apr 2021 23:33:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60858 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230319AbhDVDc6 (ORCPT ); Wed, 21 Apr 2021 23:32:58 -0400 Received: from mail-yb1-xb2b.google.com (mail-yb1-xb2b.google.com [IPv6:2607:f8b0:4864:20::b2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47B5AC06174A; Wed, 21 Apr 2021 20:32:24 -0700 (PDT) Received: by mail-yb1-xb2b.google.com with SMTP id v72so29015206ybe.11; Wed, 21 Apr 2021 20:32:24 -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=dxHlgtvoXvn9RKORV+ZqAcBLqkSOd7zAiDpIufo/J9g=; b=uxirDz0cdZNdtB/wqvNS2E48bwtE1shK+82+vbj22ygfJmgjrhUaivA04hBl06w3un cA/dYZ6d1bdQAUz+OxOUfi1Y/ooWbs1AOXeMfBugYbGYkvqBX2/j/71wuBzeJwGkNDPs YvsanmUu+fcNnlN+v5n09/rX/4BoB4wgVNdCwSVzcous+6/4YYtPE8hUusCFoaAi2wgM BkEyPa2i2hhVIiI0ylrcknY4dJBrDlQvMYS5b+6OgqI2Xb0YgdhfhDsSsALBl5H+qKyk wVoyM6OLU20C9ZLKpKdwvJmL6jJwZNLkRlO3sEic9G5LACoB+w/lZxaUhgySehpTgPav m2Og== 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=dxHlgtvoXvn9RKORV+ZqAcBLqkSOd7zAiDpIufo/J9g=; b=RchZ2kzLtCdb6bXvDTRd5TcBeW8thzfwI2EABntA/Taqlzu4N6pmnwnuNdbOLfqbdV VIY9p7mLcNRjaQ8NqWusIiWkZNArEHnDk9ET5Mu3W28wmQ86PKxt9XPrQuM4d/90A/JV kUgqclHSniEfBOKLbU03I9whEHL2YbOrodT+JaTFHdW1DIBACyrkHhsRKuNCQSLH6947 bttI8eBMNkDeZ6oH1B9nhvsGcrxFnLim13MOJc9qwSznX+T6JtioRP4XIF8NIKb+F2DO zFdNnwVVwDE2O5CfwJCnpwR26S5OqtUeZAhk9VBVa+utGdfQhtxLlE7gS+6lTG5D4THq DUzA== X-Gm-Message-State: AOAM532Gt3evbVCuPN3/IXAyY79OzMQZ3KSFQJpX7TjghMO2saDV2V6+ nTm/EPD+zX6eDNRnqMfdjleabuUDx5GB1Y2cPZg= X-Google-Smtp-Source: ABdhPJzTL2qLrVEwrZs1aIsGNyiGiFwut9Mozw4psdb+wX5nYOEqmSRa+JtYp/m+Z4Wb7+giXr3RJ1lDPRDHdoCyJ1Y= X-Received: by 2002:a25:9942:: with SMTP id n2mr1841844ybo.230.1619062343596; Wed, 21 Apr 2021 20:32:23 -0700 (PDT) MIME-Version: 1.0 References: <20210421190736.1538217-1-linux@rasmusvillemoes.dk> In-Reply-To: <20210421190736.1538217-1-linux@rasmusvillemoes.dk> From: Andrii Nakryiko Date: Wed, 21 Apr 2021 20:32:12 -0700 Message-ID: Subject: Re: [PATCH] bpf: remove pointless code from bpf_do_trace_printk() To: Rasmus Villemoes Cc: Daniel Borkmann , Alan Maguire , Steven Rostedt , bpf , open list Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 21, 2021 at 6:19 PM Rasmus Villemoes wrote: > > The comment is wrong. snprintf(buf, 16, "") and snprintf(buf, 16, > "%s", "") etc. will certainly put '\0' in buf[0]. The only case where > snprintf() does not guarantee a nul-terminated string is when it is > given a buffer size of 0 (which of course prevents it from writing > anything at all to the buffer). > > Remove it before it gets cargo-culted elsewhere. > > Signed-off-by: Rasmus Villemoes > --- > kernel/trace/bpf_trace.c | 3 --- > 1 file changed, 3 deletions(-) > The change looks good to me, but please rebase it on top of the bpf-next tree. This is not a bug, so it doesn't have to go into the bpf tree. As it is right now, it doesn't apply cleanly onto bpf-next. > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index b0c45d923f0f..4ee55df84cd3 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -412,9 +412,6 @@ static __printf(1, 0) int bpf_do_trace_printk(const char *fmt, ...) > va_start(ap, fmt); > ret = vsnprintf(buf, sizeof(buf), fmt, ap); > va_end(ap); > - /* vsnprintf() will not append null for zero-length strings */ > - if (ret == 0) > - buf[0] = '\0'; > trace_bpf_trace_printk(buf); > raw_spin_unlock_irqrestore(&trace_printk_lock, flags); > > -- > 2.29.2 >