From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f43.google.com (mail-ed1-f43.google.com [209.85.208.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E8D7510E4 for ; Tue, 30 Apr 2024 00:59:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714438796; cv=none; b=rZfGrZ/64+q2v7VBP9/48uM8/kQv9TZ0FdQW5pGH4tmYJHhvtJfxMlrQw675E/83jx/b56IBgm0BnB0eL0/ZztCxe5liljb0i4ibfd3v3zx6zFtxZH17NJ4Zpi1vHzdmaeZznJCIGaoS/TF061kKGRY1jjwYygNa8xFNvTHeA6c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714438796; c=relaxed/simple; bh=rZ5Fgvfjroac2GiLwSMgIhQ7CG5p1B8aQRKKwWjaFBg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uXwKwEJax0lPvpauxjq6TLfRzadAC0YObctwX7mdgSbAx424TNjg5y3IEbsMgfuCNDwppqd7fHtGq+cvb9IddVWiDa0UjlrV9iHgq+F6bL8URh9woPlL7vXs1RIV5nZ6VIuVSAucgucWlhcFVTugcaF34RR006YWUbONV9G+18w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=EaAHAIU+; arc=none smtp.client-ip=209.85.208.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EaAHAIU+" Received: by mail-ed1-f43.google.com with SMTP id 4fb4d7f45d1cf-57288691c07so1614688a12.3 for ; Mon, 29 Apr 2024 17:59:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1714438793; x=1715043593; darn=lists.linux.dev; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=0AW/wYh4RsDtCMHIZdU80eftqWkVY8DHoSo6I6qnwxU=; b=EaAHAIU+sDQpIk9oK7k0JJjrr1eQo4GG9EUuFxa52Yb6RKMegc3vKOT/Hp9Ex6mATC kVRWggHNW7tb1+rdA0icN2g8L+ROTP9lJjog910reXIoSMVv+BU1lKDfe4Wd4ckpKjj8 dFhab6g50niYnpHT7kIJZ30dZKze1TP/yWb8fjslJTZy6PpQVVVOpTiRr5GNwXxell3d JH0/BXnY5S+tDMFCoyWqky4hsm4iWQEGNA+umWZldVoxEFi0epPdsFJrDlnYshOwufrx j8sIMlwc5heXBzWhzYwDp7LsuZNu3l9gi6ve+dfW+OPB5JcYArryJdA/hq2WHjn4uQHR ILrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714438793; x=1715043593; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=0AW/wYh4RsDtCMHIZdU80eftqWkVY8DHoSo6I6qnwxU=; b=NYNBl8vT9eGESxapw9SgPQSkXS2T4p/Gf4ULwRTJGKPWqB6T943qyQydl5nwtPseRR v8URWNKVl8fDwJbhLKDsE/vAHgjs4YbmJLaU+l1hRNwrKBYS/ZdntW5OgoEbegvCre5u NxsZQ8DjI08oaE6McC05IlXH9ckNGErZM6ABw1BaJ+aGAmNhrLVVQFX+WPpHlN+8lPE6 Ss6IcpzOV6bPIuZjsOn14znwhhZnBxlhNOS+WK1fREKgNE7HHF1vcyAVEg+vvbej3S3l 0sNh/hRGJhm3ZsTlOeFdJAGZYrnn9cXr6v7vIEdSUMt83LtvJJkUR7jcOo8MphMUGzyr 9rrA== X-Forwarded-Encrypted: i=1; AJvYcCXyejngRYz65zMq7pdnZnXOIUnpJM6Nn89YXvlZqO+lGzauiTFC6tzbiWWKqiaoHNmkm1iEHurgwqoSvrNTAxmAQSxD67c3 X-Gm-Message-State: AOJu0YzxGi/rgAt3Sdkp0a6BdDc5Lh+B3z2j40mlsU+JHbdcZjw1Y3v0 TgG1k3IAwmDNSmFtxZLMgWQcSqYLki5L6g5/wYJJdP/rj9e0KnOz X-Google-Smtp-Source: AGHT+IHdNhQ1o7yqt5336ceWzkBhi+68iQi+cVplWUMRflPGIyCHcqMyO6RMKJHvbgODYQmgqdAYrA== X-Received: by 2002:a50:d593:0:b0:572:2264:76ec with SMTP id v19-20020a50d593000000b00572226476ecmr8068209edi.2.1714438792982; Mon, 29 Apr 2024 17:59:52 -0700 (PDT) Received: from skbuf ([2a02:2f04:d70a:9c00::b2c]) by smtp.gmail.com with ESMTPSA id ef9-20020a05640228c900b00571bde3b0a4sm13261791edb.34.2024.04.29.17.59.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Apr 2024 17:59:52 -0700 (PDT) Date: Tue, 30 Apr 2024 03:59:49 +0300 From: Vladimir Oltean To: Joseph Huang Cc: Joseph Huang , netdev@vger.kernel.org, Andrew Lunn , Florian Fainelli , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Roopa Prabhu , Nikolay Aleksandrov , Linus =?utf-8?Q?L=C3=BCssing?= , linux-kernel@vger.kernel.org, bridge@lists.linux.dev Subject: Re: [PATCH RFC net-next 07/10] net: dsa: mv88e6xxx: Track bridge mdb objects Message-ID: <20240430005949.44lcegwhmcetpddm@skbuf> References: <20240402001137.2980589-1-Joseph.Huang@garmin.com> <20240402001137.2980589-8-Joseph.Huang@garmin.com> <20240402122343.a7o5narxsctrkaoo@skbuf> <20240405110745.si4gc567jt5gwpbr@skbuf> Precedence: bulk X-Mailing-List: bridge@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Apr 29, 2024 at 06:07:25PM -0400, Joseph Huang wrote: > Something like this (some layers omitted for brevity)? > > +br_iterator > | for each mdb > | _br_switchdev_mdb_notify > rtnl_lock | without F_DEFER flag > | | | > +switchdev_port_attr_set_deferred | +switchdev_port_obj_notify > | | | > +dsa_port_mrouter | +dsa_user_port_obj_a/d > | | | > +mv88e6xxx_port_mrouter----------+ +mv88e6xxx_port_obj_a/d > | > +--------------------------------------+ > | > rtnl_unlock At a _very_ superficial glance, I don't think you are properly accounting for the fact that even with rtnl_lock() held, there are still SWITCHDEV_OBJ_ID_PORT_MDB events which may be pending on the switchdev chain. Without a switchdev_deferred_process() flush call, you won't be getting rid of them, so when you rtnl_unlock(), they will still run. Even worse, holding rtnl_lock() will not stop the bridge multicast layer from modifying its br->mdb_list; only br->multicast_lock will. So you may be better off also acquiring br->multicast_lock, and notifying the MDB entries to the switchdev chain _with_the F_DEFER flag. > Note that on the system I tested, each register read/write takes about 100us > to complete. For 100's of mdb groups, this would mean that we will be > holding rtnl lock for 10's of ms. I don't know if it's considered too long. Not sure how this is going to be any better if the iteration over MDB entries is done 100% in the driver, though - since its hook, dsa_port_mrouter(), runs entirely under rtnl_lock(). Anyway, with the SWITCHDEV_F_DEFER flag, maybe the mdb object notifications can be made to run by switchdev only a few at a time, to give the network stack time to do other things as well.