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[23.128.96.18]) by mx.google.com with ESMTP id u2si4422818edy.251.2020.09.10.12.27.10; Thu, 10 Sep 2020 12:27:32 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727894AbgIJT03 (ORCPT + 99 others); Thu, 10 Sep 2020 15:26:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726899AbgIJT0S (ORCPT ); Thu, 10 Sep 2020 15:26:18 -0400 Received: from shards.monkeyblade.net (shards.monkeyblade.net [IPv6:2620:137:e000::1:9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E0FCC061756; Thu, 10 Sep 2020 12:26:08 -0700 (PDT) Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id B092F12A2A784; Thu, 10 Sep 2020 12:09:20 -0700 (PDT) Date: Thu, 10 Sep 2020 12:26:06 -0700 (PDT) Message-Id: <20200910.122606.1088855592206611092.davem@davemloft.net> To: paul.davey@alliedtelesis.co.nz Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v2 0/3] Allow more than 255 IPv4 multicast interfaces From: David Miller In-Reply-To: <20200907220408.32385-1-paul.davey@alliedtelesis.co.nz> References: <20200907220408.32385-1-paul.davey@alliedtelesis.co.nz> X-Mailer: Mew version 6.8 on Emacs 27.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [2620:137:e000::1:9]); Thu, 10 Sep 2020 12:09:20 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paul Davey Date: Tue, 8 Sep 2020 10:04:05 +1200 > Currently it is not possible to use more than 255 multicast interfaces > for IPv4 due to the format of the igmpmsg header which only has 8 bits > available for the VIF ID. There is space available in the igmpmsg > header to store the full VIF ID in the form of an unused byte following > the VIF ID field. There is also enough space for the full VIF ID in > the Netlink cache notifications, however the value is currently taken > directly from the igmpmsg header and has thus already been truncated. > > Adding the high byte of the VIF ID into the unused3 byte of igmpmsg > allows use of more than 255 IPv4 multicast interfaces. The full VIF ID > is also available in the Netlink notification by assembling it from > both bytes from the igmpmsg. > > Additionally this reveals a deficiency in the Netlink cache report > notifications, they lack any means for differentiating cache reports > relating to different multicast routing tables. This is easily > resolved by adding the multicast route table ID to the cache reports. > > changes in v2: > - Added high byte of VIF ID to igmpmsg struct replacing unused3 > member. > - Assemble VIF ID in Netlink notification from both bytes in igmpmsg > header. Series applied, thank you.