Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756020Ab0KVTOJ (ORCPT ); Mon, 22 Nov 2010 14:14:09 -0500 Received: from yop.chewa.net ([91.121.105.214]:40024 "EHLO yop.chewa.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752841Ab0KVTOH convert rfc822-to-8bit (ORCPT ); Mon, 22 Nov 2010 14:14:07 -0500 X-Greylist: delayed 383 seconds by postgrey-1.27 at vger.kernel.org; Mon, 22 Nov 2010 14:14:07 EST From: "=?iso-8859-15?q?R=E9mi?= Denis-Courmont" Organization: Remlab.net To: Alban Crequy , netdev@vger.kernel.org Subject: Re: [PATCH 7/9] AF_UNIX: Documentation on multicast Unix Sockets Date: Mon, 22 Nov 2010 21:07:40 +0200 User-Agent: KMail/1.13.5 (Linux/2.6.35.8; KDE/4.4.5; i686; ; ) Cc: linux-kernel@vger.kernel.org References: <20101122183447.124afce5@chocolatine.cbg.collabora.co.uk> <1290450982-17480-7-git-send-email-alban.crequy@collabora.co.uk> In-Reply-To: <1290450982-17480-7-git-send-email-alban.crequy@collabora.co.uk> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 8BIT Message-Id: <201011222107.41548.remi@remlab.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1508 Lines: 35 Le lundi 22 novembre 2010 20:36:20 Alban Crequy, vous avez ?crit : > +Multicast Unix sockets > +====================== > + > +Multicast group memberships are stored in struct unix_mcast nodes. An Unix > +socket can join several multicast groups. Struct unix_mcast nodes are > doubly +linked: > +- In (struct unix_sock)->mcast_subscriptions > +- In (struct unix_sock)->mcast_members I may be stupid, but I found this whole documentation very confusing, and so the API it tries to describe. Traditionally: - Senders may or not may be part of the group and are not kept track of. - Receivers join to the group then receive message sent to it. - Loopback defines whether a sender receives its own echo if it sends to a group that it has joined. - If connected to a multicast group, messages from the socket are routed to the group (in absence of a contradictoy socket address). This has no effect on membership to the multicast group under any circumstance. You cannot 'listen' or 'accept' on a multicast group. So I am not entirely clear what semantics your patchset is following. But it does not seem like "multicast" to me and therefore seems not very well documented :-( -- R?mi Denis-Courmont http://www.remlab.net/ http://fi.linkedin.com/in/remidenis -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/