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=-8.1 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,NICE_REPLY_A,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 E60AEC433E2 for ; Sun, 13 Sep 2020 10:12:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A46E3206B8 for ; Sun, 13 Sep 2020 10:12:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="InksbMVj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725919AbgIMKMT (ORCPT ); Sun, 13 Sep 2020 06:12:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60120 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725916AbgIMKMM (ORCPT ); Sun, 13 Sep 2020 06:12:12 -0400 Received: from mail-ed1-x544.google.com (mail-ed1-x544.google.com [IPv6:2a00:1450:4864:20::544]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F005C061573; Sun, 13 Sep 2020 03:12:11 -0700 (PDT) Received: by mail-ed1-x544.google.com with SMTP id c8so14732373edv.5; Sun, 13 Sep 2020 03:12:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=IMYFUzqiW20Iay+Ejl4kU0YXATxavEXThV4F8sBN6q8=; b=InksbMVjgPv+eom5oL2+Zo4rmfq5bAhgYroJtb4xe2mx9DVUitt2CuafAMzXIgm8/X fZR56LQUsjw5aKSNu/hV1kn4pAg1whJOaC2kqLtXneg2P7Uuy7GXwHvcirkBH2QHkxyT SQBpOTEXWu9c44BKNvWaKBCIUplWoFyuiKuz+EsQYNsJzviLNbMWwuuNZr8nlHauLt0f hlDTAMPmDDNYSltRRmxAAMj6hzUiB6xkFook79dYPqkmADwyy9dDqYY+WDi+rdnEgj05 tiCiT1X4p0LqYyHvaKeEIykyxRZN7tj14vvrQzI+FRf8vRVXSkgge95fi3dZEjrhPM5D g7IA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=IMYFUzqiW20Iay+Ejl4kU0YXATxavEXThV4F8sBN6q8=; b=rWfZoNFv1FOKGsPR70ScKGuGfOK+W413E7xwo/xrcXx7Aa66r3hoG+f9nZVsN9IuJe bvGoxBwwXuHkBPRGKCE7hmIFkVNcHSx3Wik1KsFf3Dr7ehChzSwRXLd2eJHrWbj1NHNv dLx9aMCnGpeRcU8zOEc8b/SJZVbyfYX9yAXAOma6wvtnKgOvIMdMd5seVWVW+VT2Ow49 dtgBj7rNgHhGhZnbiV5iF3llVR4tN1Ce62khGl0ENLlDyGu2Wwu33fwdT6LCrKuHZFMh RaaPhQrFm6TKRWPU50grQ7SW+4/wJeT57zNlTz7UtmuOZh6yIzoUR9Jt/8cwa2RqlR1O isjg== X-Gm-Message-State: AOAM532lpYKXYfxmlOnQ0dpz2E9d6dX9fpL7001f6iQXBs3/I89ZT6b+ 8wOvkZnUsy1gdzKHwNnH3bw2egRAkG0= X-Google-Smtp-Source: ABdhPJx48SitZEcZDyr43jtNWWshqTXviMaD+tRE732awHaswdUb1ag54Dzw2HQppCkKbZHcjdSIog== X-Received: by 2002:a50:bb65:: with SMTP id y92mr12008083ede.53.1599991929793; Sun, 13 Sep 2020 03:12:09 -0700 (PDT) Received: from [192.168.0.105] ([77.124.39.109]) by smtp.gmail.com with ESMTPSA id qu11sm5113408ejb.15.2020.09.13.03.12.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 13 Sep 2020 03:12:09 -0700 (PDT) Subject: Re: [PATCH net-next] net: ethernet: mlx4: Avoid assigning a value to ring_cons but not used it anymore in mlx4_en_xmit() To: David Miller , luojiaxing@huawei.com Cc: kuba@kernel.org, idos@mellanox.com, ogerlitz@mellanox.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com References: <1599898095-10712-1-git-send-email-luojiaxing@huawei.com> <20200912.182219.1013721666435098048.davem@davemloft.net> From: Tariq Toukan Message-ID: Date: Sun, 13 Sep 2020 13:12:05 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200912.182219.1013721666435098048.davem@davemloft.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/13/2020 4:22 AM, David Miller wrote: > From: Luo Jiaxing > Date: Sat, 12 Sep 2020 16:08:15 +0800 > >> We found a set but not used variable 'ring_cons' in mlx4_en_xmit(), it will >> cause a warning when build the kernel. And after checking the commit record >> of this function, we found that it was introduced by a previous patch. >> >> So, We delete this redundant assignment code. >> >> Fixes: 488a9b48e398 ("net/mlx4_en: Wake TX queues only when there's enough room") >> >> Signed-off-by: Luo Jiaxing > > Looks good, applied, thanks. > Hi Luo, I didn't get a chance to review it during the weekend. The ring_cons local variable is used in line 903: https://elixir.bootlin.com/linux/v5.9-rc4/source/drivers/net/ethernet/mellanox/mlx4/en_tx.c#L903 AVG_PERF_COUNTER depends on the compile-time definition of MLX4_EN_PERF_STAT. Otherwise it is a nop. 1. Your patch causes a degradation to the case when MLX4_EN_PERF_STAT is defined. 2. When MLX4_EN_PERF_STAT is not defined, we should totally remove the local variable declaration, not only its usage. Please let me know if you're planning to fix this. Otherwise I'll do. Regards, Tariq