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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 EBCA6C282C4 for ; Tue, 5 Feb 2019 02:53:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A665B2081B for ; Tue, 5 Feb 2019 02:53:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="E3YI21kj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726924AbfBECxk (ORCPT ); Mon, 4 Feb 2019 21:53:40 -0500 Received: from mail-pl1-f171.google.com ([209.85.214.171]:38809 "EHLO mail-pl1-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726518AbfBECxj (ORCPT ); Mon, 4 Feb 2019 21:53:39 -0500 Received: by mail-pl1-f171.google.com with SMTP id e5so861115plb.5 for ; Mon, 04 Feb 2019 18:53:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=j1OWC5q8uaCPm8tTaRqNxElgULUPe7azay+6JZ9zhzU=; b=E3YI21kjy8scq4nsI9fHIOXoGsmEFNya+C5RjQ1jWDUnlrJEJYSGfrMGv9+KzTscyL O+dlTDnl3wljPdTZ6PcJamUOz84VMM88fycBGLN++U+wbYrvLkZkwxQEmCAmbnQgzxGU KFJhJYh6Vm4BnhAEx2QTEbaEwmi5MBwFNGSeUNR1sLVFVyhjehZ9pEPPkBaQ4iIatRpG /IxclSuTj4n4Wl7y+VjnPtcp+WvYnBIW2pQhZbZjOY/iJ4B7ZtPUEK/ZVbdEQ6wBEQzN vN5Ng7PUE2C6M/XG6OgTlPePWbBlcPWE67RyZqEtZ8lVa3403HJ1igcxkhPR1M1sxsNU 8WMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=j1OWC5q8uaCPm8tTaRqNxElgULUPe7azay+6JZ9zhzU=; b=DJD2twsE1JdHXVhGC3DWqBz2sahatQmRu2HUbiRkl+vfZliKWzNVVHmitSafCuSnfx DuJnLZFzwwUlYBSyAHfHevGB4ZxB2NkvjdePpK5Y/iwpnMxevVZRQi837+UCmxSNiJ3w 6aPLIdTe4cQjYt+KwcvBkNmjWOEsLS+1vyNiBg/3g2HqTHOJc7Pz4ZjxLNe/3bmAdBpg 1zKNZe4dEvl37IWh+othCUubFsndxE7CiGUfTCjd+UxcixBmz1LeJgkVwquAOeWsaqHX /DvA6TAhft4nTEnLEWflqmJKoMUFfP7T/YQ8diKiHrsAqDz/xEhVsOjnUSWM/0L0HMc8 A0zQ== X-Gm-Message-State: AHQUAubTRirO/DeRxY4EaO2pH9UWQiVOM4mJiY/2lU8jTUFP6BEZpkyz 1HWqzxzv0HbmP/lg8CUKspMQ7r1C X-Google-Smtp-Source: AHgI3IZYVDmT0N43iAIdtXLcWvcTniIsFgSoHYRCr+7tqIgIa8FXPcG4DODGS5XIR6f8+5uvUbDJYA== X-Received: by 2002:a17:902:15a8:: with SMTP id m37mr2739402pla.129.1549335218898; Mon, 04 Feb 2019 18:53:38 -0800 (PST) Received: from [172.27.227.2] ([216.129.126.118]) by smtp.googlemail.com with ESMTPSA id x11sm2361360pfe.72.2019.02.04.18.53.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Feb 2019 18:53:37 -0800 (PST) Subject: Re: Compiler warning - ipv4 fib_trie To: Koen Vandeputte , netdev@vger.kernel.org References: From: David Ahern Message-ID: <048e34cb-d920-60f5-7e52-ce3d2b4e00ae@gmail.com> Date: Mon, 4 Feb 2019 18:53:35 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2/4/19 3:55 AM, Koen Vandeputte wrote: > Hi All, > > During compilation of kernel 4.14.96 and 5.0-rc5 I'm seeing following > warning: > > net/ipv4/fib_trie.c: In function 'fib_trie_unmerge': > net/ipv4/fib_trie.c:1749:8: warning: 'local_tp' may be used > uninitialized in this function [-Wmaybe-uninitialized] >     if (fib_insert_alias(lt, local_tp, local_l, new_fa, >         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >            NULL, l->key)) { >            ~~~~~~~~~~~~~ > > Code: > > https://elixir.bootlin.com/linux/v5.0-rc5/source/net/ipv4/fib_trie.c#L1731 > > Looks like 'local_tp' should be NULL-ified > > > Thanks, > > Koen > I believe that is a false positive. If you analyze the loop, local_tp is set when local_l is NULL and it is set before the first use. I am surprised the compiler can not track that. fib_find_node has 1 return point and local_tp is set right before.