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=-2.7 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,SPF_HELO_NONE,SPF_PASS 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 1739BC433FE for ; Thu, 2 Sep 2021 20:21:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1CB060200 for ; Thu, 2 Sep 2021 20:21:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346117AbhIBUW2 (ORCPT ); Thu, 2 Sep 2021 16:22:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232042AbhIBUW0 (ORCPT ); Thu, 2 Sep 2021 16:22:26 -0400 Received: from mail-ed1-x52a.google.com (mail-ed1-x52a.google.com [IPv6:2a00:1450:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC4B3C061575; Thu, 2 Sep 2021 13:21:27 -0700 (PDT) Received: by mail-ed1-x52a.google.com with SMTP id g21so4749126edw.4; Thu, 02 Sep 2021 13:21:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=AFcTJM/1mhNsgSgPURjx0gJ3fOMmNuJ4K813cVRnYVk=; b=itrqqWrCMK/r+xsLy+tUfzWIWp2tlWX5pTAYZW9sVDuoOHHaukHQkyAlqPC5MPOs0j p7SgxY0Y4m+yEKIH8p+EBF9SQBjaljHwGftI88BaIWXsrys77OUe5GdrIEASrzxlTjxy qt1alNX+6DDn54i0oHp4ZB4ZYs/jgftbd+f61xWbm2RdFcl/kOCnckw1ZtOhzJXeiQN0 TbV5YYjfWspD3oW58TmifB4CbtWLcEbxYK9KhLkPihg0ZRVOVm/gtzW/za25HgE2vSSc 8MdjENR5h1J0wRjGZpBY9mTiml2hJ+InEtS3tKJ5+IWUw6rI7XI7jbhuUB+Bq4RMIVJH 2RMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=AFcTJM/1mhNsgSgPURjx0gJ3fOMmNuJ4K813cVRnYVk=; b=FU/xZm48z9p5X7UTH1cbSJhqOKboOz5gBpXbj6TMoxWJ5z+nN228q/M6ijvCdNPN8j iaaeHTB+rBJ26sBMyJVYC98gfwxY0sldH5kH7vkKJXstymDBypZ3Ia0v2w5Fm/pyeIAW vXnsl4tMZglCRSZfonFe+Xio0CMOqYM/J/I4vLq/3TzKwn1kXVrAg1blkCJpvy1b4xNk QBZ4HXEY34H402XmsAzd8fNnjkzlkbfTHIE3EG2IcJ+WKQyDSlVsv8WNwmvkpyQ5kbCi lmtswaulBspePDzz9OqNW+7Xj7EE/kegBMR9DjJqjR/s4Q6ChKOvg56li1Rfo7NyirKN icHA== X-Gm-Message-State: AOAM532CX6Pz8nNv6evHRzjUeWRhtfRmR5gUElm658OrLhdMwVbUFBx7 opfgFgVCJjelSrpqX3Mk/7s= X-Google-Smtp-Source: ABdhPJyV7/E/wloHWVt8oJoNY02iTbn4GPJ/wFEaqR2C8ezOUCOj2KCMggLFCY4qFWtnb6jl8HtcpA== X-Received: by 2002:aa7:c313:: with SMTP id l19mr137763edq.131.1630614086275; Thu, 02 Sep 2021 13:21:26 -0700 (PDT) Received: from skbuf ([82.78.148.104]) by smtp.gmail.com with ESMTPSA id b5sm1630291ejq.56.2021.09.02.13.21.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Sep 2021 13:21:25 -0700 (PDT) Date: Thu, 2 Sep 2021 23:21:24 +0300 From: Vladimir Oltean To: "Russell King (Oracle)" Cc: Vladimir Oltean , "netdev@vger.kernel.org" , Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Lunn , Heiner Kallweit , "David S. Miller" , Jakub Kicinski , Vivien Didelot , Florian Fainelli , "linux-kernel@vger.kernel.org" , Linus Walleij , Alvin =?utf-8?Q?=C5=A0ipraga?= , ACPI Devel Maling List , kernel-team , Len Brown Subject: Re: [RFC PATCH net-next 0/3] Make the PHY library stop being so greedy when binding the generic PHY driver Message-ID: <20210902202124.o5lcnukdzjkbft7l@skbuf> References: <20210901225053.1205571-1-vladimir.oltean@nxp.com> <20210902121927.GE22278@shell.armlinux.org.uk> <20210902123532.ruvuecxoig67yv5v@skbuf> <20210902132635.GG22278@shell.armlinux.org.uk> <20210902152342.vett7qfhvhiyejvo@skbuf> <20210902163144.GH22278@shell.armlinux.org.uk> <20210902171033.4byfnu3g25ptnghg@skbuf> <20210902175043.GK22278@shell.armlinux.org.uk> <20210902190507.shcdmfi3v55l2zuj@skbuf> <20210902200301.GM22278@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210902200301.GM22278@shell.armlinux.org.uk> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 02, 2021 at 09:03:01PM +0100, Russell King (Oracle) wrote: > On Thu, Sep 02, 2021 at 10:05:07PM +0300, Vladimir Oltean wrote: > > On Thu, Sep 02, 2021 at 06:50:43PM +0100, Russell King (Oracle) wrote: > > > On Thu, Sep 02, 2021 at 05:10:34PM +0000, Vladimir Oltean wrote: > > > > On Thu, Sep 02, 2021 at 05:31:44PM +0100, Russell King (Oracle) wrote: > > > > > On Thu, Sep 02, 2021 at 06:23:42PM +0300, Vladimir Oltean wrote: > > > > > > On Thu, Sep 02, 2021 at 02:26:35PM +0100, Russell King (Oracle) wrote: > > > > > > > Debian has had support for configuring bridges at boot time via > > > > > > > the interfaces file for years. Breaking that is going to upset a > > > > > > > lot of people (me included) resulting in busted networks. It > > > > > > > would be a sure way to make oneself unpopular. > > > > > > > > > > > > > > > I expect there to be 2 call paths of phy_attach_direct: > > > > > > > > - At probe time. Both the MAC driver and the PHY driver are probing. > > > > > > > > This is what has this patch addresses. There is no issue to return > > > > > > > > -EPROBE_DEFER at that time, since drivers connect to the PHY before > > > > > > > > they register their netdev. So if connecting defers, there is no > > > > > > > > netdev to unregister, and user space knows nothing of this. > > > > > > > > - At .ndo_open time. This is where it maybe gets interesting, but not to > > > > > > > > user space. If you open a netdev and it connects to the PHY then, I > > > > > > > > wouldn't expect the PHY to be undergoing a probing process, all of > > > > > > > > that should have been settled by then, should it not? Where it might > > > > > > > > get interesting is with NFS root, and I admit I haven't tested that. > > > > > > > > > > > > > > I don't think you can make that assumption. Consider the case where > > > > > > > systemd is being used, DSA stuff is modular, and we're trying to > > > > > > > setup a bridge device on DSA. DSA could be probing while the bridge > > > > > > > is being setup. > > > > > > > > > > > > > > Sadly, this isn't theoretical. I've ended up needing: > > > > > > > > > > > > > > pre-up sleep 1 > > > > > > > > > > > > > > in my bridge configuration to allow time for DSA to finish probing. > > > > > > > It's not a pleasant solution, nor a particularly reliable one at > > > > > > > that, but it currently works around the problem. > > > > > > > > > > > > What problem? This is the first time I've heard of this report, and you > > > > > > should definitely not need that. > > > > > > > > > > I found it when upgrading the Clearfog by the DSL modems to v5.13. > > > > > When I rebooted it with a previously working kernel (v5.7) it has > > > > > never had a problem. With v5.13, it failed to add all the lan ports > > > > > into the bridge, because the bridge was still being setup by the > > > > > kernel while userspace was trying to configure it. Note that I have > > > > > extra debug in my kernels, hence the extra messages: > > > > > > > > Ok, first you talked about the interfaces file, then systemd. If it's > > > > not about systemd's network manager then I don't see how it is relevant. > > > > > > You're reading in stuff to what I write that I did not write... I said: > > > > > > "Consider the case where systemd is being used, DSA stuff is modular, > > > and we're trying to setup a bridge device on DSA." > > > > > > That does not mean I'm using systemd's network manager - which is > > > something I know little about and have never used. > > > > You should definitely try it out, it gets a lot of new features added > > all the time, it uses the netlink interface, it reacts on udev events. > > > > > The reason I mentioned systemd is precisely because with systemd, you > > > get a hell of a lot happening parallel - and that's significiant in > > > this case, because it's very clear that modules are being loaded in > > > parallel with networking being brought up - and that is where the > > > problems begin. In fact, modules themselves get loaded in paralllel > > > with systemd. > > > > So that's what I don't understand. You're saying that the ifupdown > > service runs in parallel with systemd-modules-load.service, and > > networking is a kernel module? Doesn't that mean it behaves as expected, > > then? /shrug/ > > Have you tried adding an 'After=systemd-modules-load.service' dependency > > to the ifupdown service? I don't think that DSA is that bad that it > > registers its net devices outside of the process context in which the > > insmod mv88e6xxx.ko is called. Quite the opposite, I think (but I > > haven't actually taken a close look yet) that the component stuff > > Saravana is proposing would do exactly that. So you "fix" one issue, you > > introduce another. > > # systemctl list-dependencies networking.service > networking.service > ├─ifupdown-pre.service > ├─system.slice > └─network.target > # systemctl list-dependencies ifupdown-pre.service > ifupdown-pre.service > ├─system.slice > └─systemd-udevd.service > > Looking in the service files for a better idea: > > networking.service: > Requires=ifupdown-pre.service > Wants=network.target > After=local-fs.target network-pre.target apparmor.service systemd-sysctl.service systemd-modules-load.service ifupdown-pre.service > Before=network.target shutdown.target network-online.target > > ifupdown-pre.service: > Wants=systemd-udevd.service > After=systemd-udev-trigger.service > Before=network.target > > So, the dependency you mention is already present. As is a dependency > on udev. The problem is udev does all the automatic module loading > asynchronously and in a multithreaded way. > > I don't think there's a way to make systemd wait for all module loads > to complete. So ifupdown-pre.service has a call to "udevadm settle". This "watches the udev event queue, and exits if all current events are handled", according to the man page. But which current events? ifupdown-pre.service does not have the dependency on systemd-modules-load.service, just networking.service does. So maybe ifupdown-pre.service does not wait for DSA to finish initializing, then it tells networking.service that all is ok.