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=-5.1 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,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 C2FACC388F7 for ; Tue, 10 Nov 2020 15:05:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A4C5206B2 for ; Tue, 10 Nov 2020 15:05:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BZCydrXf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731242AbgKJPF0 (ORCPT ); Tue, 10 Nov 2020 10:05:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726721AbgKJPF0 (ORCPT ); Tue, 10 Nov 2020 10:05:26 -0500 Received: from mail-io1-xd43.google.com (mail-io1-xd43.google.com [IPv6:2607:f8b0:4864:20::d43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7DE24C0613CF for ; Tue, 10 Nov 2020 07:05:24 -0800 (PST) Received: by mail-io1-xd43.google.com with SMTP id n129so14412415iod.5 for ; Tue, 10 Nov 2020 07:05:24 -0800 (PST) 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=QiO5/DXNXtpuh6pt0YMU0h8raRvXdoQZZ/8S74SQK5U=; b=BZCydrXf9hLOcbb77GecIA58sJemggzTVT7YlAVAyA+PH+ZkQAoQTFhxrXNs5pBRT+ +rwncrPFvXp7kXQhIU6rHfEorzXyq/LwUsOW62p2HKkAOke2RdMlOJT4LtiqYC8IfYi5 23LJosOIb4wefYL33u60plGhYhN7rhLXHa85aNjzoNiLGQCQsY8RVCACy41iEGwgwsld FbacxKTxK2i6ojX+bX9p9igLjIlrEIyXDxS9fiU9EkrskCYVn4jYZcIlJDQtMnPIB6Eq iYtWbJaI/zx6MP3eg6FXNYa6cjOD7hSLzgtbrjpVWSIrbht/QEiPbgx4kEYMkJZP1Cme eagg== 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=QiO5/DXNXtpuh6pt0YMU0h8raRvXdoQZZ/8S74SQK5U=; b=QNktH49PskdRKQujKGIQg3ARXCWkGJQRaqsck6Qzf5HqrQKVrxnV76D0+uxlxxbMRQ qhd4EnK7gndzM+875v4KBIDPkNjYo93sB/f0kI97Lv8UEFklFNSOWL1FkPw4f+oRcH3Z gqTgXy4VsDjlOIC80V7akalSBPxGAXzJQb4032qkibBRrNfiz98K/Ws0P6fts2IiU51P 8aaEoaBPU5ZgU9gyzq2pOqxDrtD3JYPATo4dhHflTOrUeJjiW/UqfJ3ix+U05Buj98th 4TtZ72rYa7FquiND1OZzbzizr49GWJ5eHKXBKXg950a2zuH0nfqBgt9N8rggZutdRMj7 MEIw== X-Gm-Message-State: AOAM530iH1ZbOHR8LYZ8phfgakcD/d9odZ7FYYDiV/iegK7iPSklMWa0 84g5irjfEHqm5NzTPVkAvFA= X-Google-Smtp-Source: ABdhPJzF6QKQttQyi5+HfJLBUL2VgqYXQI/zH1kmJb0E6IeY4k4MFWYI45jjaxzPYYBF2AJH5pRxeA== X-Received: by 2002:a02:408a:: with SMTP id n132mr9150482jaa.66.1605020723847; Tue, 10 Nov 2020 07:05:23 -0800 (PST) Received: from Davids-MacBook-Pro.local ([2601:282:800:dc80:7980:a277:20c7:aa44]) by smtp.googlemail.com with ESMTPSA id s26sm5381900ioe.2.2020.11.10.07.05.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 10 Nov 2020 07:05:23 -0800 (PST) Subject: Re: [PATCH net V2] Exempt multicast addresses from five-second neighbor lifetime To: Jeff Dike , Jakub Kicinski Cc: netdev@vger.kernel.org, Nikolay Aleksandrov References: <20201109025052.23280-1-jdike@akamai.com> <20201109114733.0ee71b82@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> From: David Ahern Message-ID: <5210487b-fde2-c6f1-a065-ad25103acaed@gmail.com> Date: Tue, 10 Nov 2020 08:05:21 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 11/10/20 7:21 AM, Jeff Dike wrote: > Hi Jakub, > > On 11/9/20 2:47 PM, Jakub Kicinski wrote: >> This makes sense because mcast L2 addr is calculated, not discovered, >> and therefore can be recreated at a very low cost, correct? > > Yes. > >> Perhaps it would make sense to widen the API to any "computed" address >> rather than implicitly depending on this behavior for mcast? > > I'm happy to do that, but I don't know of any other types of addresses which are computed and end up in the neighbors table. > >> I'm not an expert tho, maybe others disagree. >> >>> +static int arp_is_multicast(const void *pkey) >>> +{ >>> + return IN_MULTICAST(htonl(*((u32 *)pkey))); >>> +} >> >> net/ipv4/arp.c:935:16: warning: cast from restricted __be32 >> >> s/u32/__be32/ >> s/htonl/ntohl/ > > Thanks, I ran sparse, but must have missed that somehow. > I missed this yesterday -- ipv4_is_multicast() is more appropriate and the norm for IPv4 addresses.