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=-16.2 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,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 95CF8C433FE for ; Tue, 14 Sep 2021 05:18:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E58760F58 for ; Tue, 14 Sep 2021 05:18:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239512AbhINFTe (ORCPT ); Tue, 14 Sep 2021 01:19:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232999AbhINFTc (ORCPT ); Tue, 14 Sep 2021 01:19:32 -0400 Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 924E1C061574; Mon, 13 Sep 2021 22:18:15 -0700 (PDT) Received: by mail-pg1-x52b.google.com with SMTP id h3so11634996pgb.7; Mon, 13 Sep 2021 22:18:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=C028bT0FNMQ2VNhaDmAaFRTruEoGmAjnB6fsgimBiLY=; b=b7+GDmi/tHbh9KnK3K3vX+jeQksjovD1asvvG5VUqlzcX1HE4fKaLX1VolzVQJ/TDx PHn4c4oYmnSejBkf4lR+InMlsNnz+KQnAQvZgarCEE3ijsOcP1RjahZ79gezpZeP5CGw 3WC1mAtJ2z4rfarwoCZRqz+iLn6un4h6dxIT6g2JUB4IZQAFlDPk9FOmFIQ+OzoslDhW jj1ux0+hFTTSoF7RONxRn/V9S7OtrhYKmW7eNVgLyCtAnoteQB9P3PSWY+dxv+5DaPt8 eCgMa6wYYvbHWmARhzVSQzJq+Mfc0te0iu1jhdJ7eAn6uGLigzz4xDEEd5OZBHRLm6oK y9zQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=C028bT0FNMQ2VNhaDmAaFRTruEoGmAjnB6fsgimBiLY=; b=Ash1vvnhxeS4O1H2Z9v9ZGapJ+R6RhADiPF+dchqXBA+28OA99lCSbQTYrlgNcf5XK fxl49Ggyr5o5uRMELMG8iZokaBJtoCzfazGJ92un1ZNwBEM7q6/RCAcN9w7X/SAaXjop UUHo3tf/eWoVfhC5YVITsN4pIM054JpU/aOqk/G6L992SnCmWa5s326hC90j7cD/XD7v qf3LiMrwJFQs87VkbImnagzGG4iXwQFxrAiXSp8pmGSoihWCQvsEfGoqHgBQC3CDz3kK /FU8VswGj9FrOD1frQc6Km11p7TXdiwEwriV58P6YvldIXaw3XyBqzDx8YlYitjrfTdk /CEA== X-Gm-Message-State: AOAM533OZwuCoNr8RnrYlejtxMrLpobVHZf61zbjv0ym+uzVse6Fuopq 33YJkRhpkutfdb2/lZeE+8IKo8S7GA4= X-Google-Smtp-Source: ABdhPJzee7e3XdPCshLwbxsW/qraVLPMCYb0p3LmZR15wIP93lJBZle/OWyNsGipvlxcGAIsYJdovg== X-Received: by 2002:a62:ee11:0:b029:3e0:88dc:193f with SMTP id e17-20020a62ee110000b02903e088dc193fmr2924525pfi.78.1631596694878; Mon, 13 Sep 2021 22:18:14 -0700 (PDT) Received: from [192.168.86.235] (c-73-241-150-58.hsd1.ca.comcast.net. [73.241.150.58]) by smtp.gmail.com with ESMTPSA id i7sm10006289pgd.56.2021.09.13.22.18.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Sep 2021 22:18:14 -0700 (PDT) Subject: Re: [PATCH net-next] net: core: fix the order in dev_put() and rtnl_lock() To: Yajun Deng , davem@davemloft.net, kuba@kernel.org Cc: nikolay@nvidia.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210914030150.5838-1-yajun.deng@linux.dev> From: Eric Dumazet Message-ID: <903c5bed-5958-8888-b55d-9c175664b2a1@gmail.com> Date: Mon, 13 Sep 2021 22:18:13 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210914030150.5838-1-yajun.deng@linux.dev> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/13/21 8:01 PM, Yajun Deng wrote: > The dev_put() should be after rtnl_lock() in case for race. > > Fixes: 893b19587534 ("net: bridge: fix ioctl locking") > Signed-off-by: Yajun Deng > --- > net/core/dev_ioctl.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c > index 0e87237fd871..9796fa35fe88 100644 > --- a/net/core/dev_ioctl.c > +++ b/net/core/dev_ioctl.c > @@ -384,8 +384,8 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data, > dev_hold(dev); > rtnl_unlock(); > err = br_ioctl_call(net, netdev_priv(dev), cmd, ifr, NULL); > - dev_put(dev); > rtnl_lock(); > + dev_put(dev); > return err; > > case SIOCSHWTSTAMP: > What race exactly are you trying to avoid ? This patch does not look needed to me.