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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 6EE47C3A5A6 for ; Sat, 31 Aug 2019 16:20:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC58C22D6D for ; Sat, 31 Aug 2019 16:20:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NQUi/G4l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728318AbfHaQUC (ORCPT ); Sat, 31 Aug 2019 12:20:02 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:42216 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728130AbfHaQUB (ORCPT ); Sat, 31 Aug 2019 12:20:01 -0400 Received: by mail-qt1-f193.google.com with SMTP id t12so11083511qtp.9 for ; Sat, 31 Aug 2019 09:20:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:message-id:from:to:cc:subject:in-reply-to:references :mime-version:content-disposition:content-transfer-encoding; bh=5zFtiCVoYMLZgbsa01BAUY/Q98D44wbb6rK19R1+JG4=; b=NQUi/G4l+xTcneVGsKLDzc+Rs+g5bkn9qi2t9YPwL3p22KIIXYF+Fp5Ul4z1WXB5Ve in25M4l3O5kOJ76exbig/iadMRYSOggHzTv1ZzBCopsBc7CbrcDeMAP5YMH8yo2rNNnq rBk/p2pqJ3/2OC1XfN5nAOR7wvJTjpK+OMxfU8IKheNS6HsT8SKqDGNLNV3nI2/JjbJZ lAb0+sKYuZ5Bp6pXBendVLuWbaNS79CWgQUimtXYnfHgNJlhxWWWykrlvnGHRRRSNGAN x3JVmpRj1ZUoI59khtb/ThWkhYeD+AH3AEaj1hEnbypQS2XStWjIOPKdYH9nhhlWfobN rN0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:from:to:cc:subject:in-reply-to :references:mime-version:content-disposition :content-transfer-encoding; bh=5zFtiCVoYMLZgbsa01BAUY/Q98D44wbb6rK19R1+JG4=; b=W1AlOkvU4qss+/XdEo2flogxswC93MzlfdQU5c9O+6yAOjR5gUKFVt9SEmOkv53lig urwlrIonx1P9EFzo6O/ezoi5utBL+Sdb+iqqM6gS2PmgXdImstym9YhKz7lVDdxLb0sc wLg18OhPu8qajn3JEAL8moODWB/ZfpxZ2xH6G2glGshHNtzSdmCgXf2c6L0A6ig+b3Xi pMY0Xc9/QJrqVxeDRmR6ml98b5+wDpq9pEBvUPexJ5YlUppBYaXPuywG1C3xL5tZdun+ J2ZkEzwKnh6AYX8JcVEFAn7Sy457kqJxaZ02cJhzzTvf5K+TzYzfI9Vi3ZGc7JhollHr MQ2Q== X-Gm-Message-State: APjAAAVs+93rO89R2rmFiL+Kc4a7D0XbRmxk6xy3oo3aa7XW4VRkBCL/ /+bIyHvGmlXCWM0KIAjH4H4BJCVX X-Google-Smtp-Source: APXvYqzdp2L70VVgK8qHhWG0cf1FGSgX97qjrn1jZQq3kHn7ZqETLnGtvO7lRNqjGn0PFerxOcK6ng== X-Received: by 2002:ac8:48c3:: with SMTP id l3mr21075847qtr.281.1567268400217; Sat, 31 Aug 2019 09:20:00 -0700 (PDT) Received: from localhost (modemcable249.105-163-184.mc.videotron.ca. [184.163.105.249]) by smtp.gmail.com with ESMTPSA id b5sm4083939qkk.78.2019.08.31.09.19.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 31 Aug 2019 09:19:59 -0700 (PDT) Date: Sat, 31 Aug 2019 12:19:58 -0400 Message-ID: <20190831121958.GC12031@t480s.localdomain> From: Vivien Didelot To: Vladimir Oltean Cc: f.fainelli@gmail.com, andrew@lunn.ch, davem@davemloft.net, netdev@vger.kernel.org, Vladimir Oltean Subject: Re: [PATCH] net: dsa: Fix off-by-one number of calls to devlink_port_unregister In-Reply-To: <20190831124619.460-1-olteanv@gmail.com> References: <20190831124619.460-1-olteanv@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Vladimir, On Sat, 31 Aug 2019 15:46:19 +0300, Vladimir Oltean wrote: > When a function such as dsa_slave_create fails, currently the following > stack trace can be seen: > > [ 2.038342] sja1105 spi0.1: Probed switch chip: SJA1105T > [ 2.054556] sja1105 spi0.1: Reset switch and programmed static config > [ 2.063837] sja1105 spi0.1: Enabled switch tagging > [ 2.068706] fsl-gianfar soc:ethernet@2d90000 eth2: error -19 setting up slave phy > [ 2.076371] ------------[ cut here ]------------ > [ 2.080973] WARNING: CPU: 1 PID: 21 at net/core/devlink.c:6184 devlink_free+0x1b4/0x1c0 > [ 2.088954] Modules linked in: > [ 2.092005] CPU: 1 PID: 21 Comm: kworker/1:1 Not tainted 5.3.0-rc6-01360-g41b52e38d2b6-dirty #1746 > [ 2.100912] Hardware name: Freescale LS1021A > [ 2.105162] Workqueue: events deferred_probe_work_func > [ 2.110287] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [ 2.117992] [] (show_stack) from [] (dump_stack+0xb4/0xc8) > [ 2.125180] [] (dump_stack) from [] (__warn+0xe0/0xf8) > [ 2.132018] [] (__warn) from [] (warn_slowpath_null+0x40/0x48) > [ 2.139549] [] (warn_slowpath_null) from [] (devlink_free+0x1b4/0x1c0) > [ 2.147772] [] (devlink_free) from [] (dsa_switch_teardown+0x60/0x6c) > [ 2.155907] [] (dsa_switch_teardown) from [] (dsa_register_switch+0x8e4/0xaa8) > [ 2.164821] [] (dsa_register_switch) from [] (sja1105_probe+0x21c/0x2ec) > [ 2.173216] [] (sja1105_probe) from [] (spi_drv_probe+0x80/0xa4) > [ 2.180920] [] (spi_drv_probe) from [] (really_probe+0x108/0x400) > [ 2.188711] [] (really_probe) from [] (driver_probe_device+0x78/0x1bc) > [ 2.196933] [] (driver_probe_device) from [] (bus_for_each_drv+0x58/0xb8) > [ 2.205414] [] (bus_for_each_drv) from [] (__device_attach+0xd0/0x168) > [ 2.213637] [] (__device_attach) from [] (bus_probe_device+0x84/0x8c) > [ 2.221772] [] (bus_probe_device) from [] (deferred_probe_work_func+0x84/0xc4) > [ 2.230686] [] (deferred_probe_work_func) from [] (process_one_work+0x218/0x510) > [ 2.239772] [] (process_one_work) from [] (worker_thread+0x2a8/0x5c0) > [ 2.247908] [] (worker_thread) from [] (kthread+0x148/0x150) > [ 2.255265] [] (kthread) from [] (ret_from_fork+0x14/0x2c) > [ 2.262444] Exception stack(0xea965fb0 to 0xea965ff8) > [ 2.267466] 5fa0: 00000000 00000000 00000000 00000000 > [ 2.275598] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > [ 2.283729] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000 > [ 2.290333] ---[ end trace ca5d506728a0581a ]--- > > devlink_free is complaining right here: > > WARN_ON(!list_empty(&devlink->port_list)); > > This happens because devlink_port_unregister is no longer done right > away in dsa_port_setup when a DSA_PORT_TYPE_USER has failed. > Vivien said about this change that: > > Also no need to call devlink_port_unregister from within dsa_port_setup > as this step is inconditionally handled by dsa_port_teardown on error. > > which is not really true. The devlink_port_unregister function _is_ > being called unconditionally from within dsa_port_setup, but not for Not from within dsa_port_setup, but from its caller dsa_tree_setup_switches. > this port that just failed, just for the previous ones which were set > up. > > ports_teardown: > for (i = 0; i < port; i++) > dsa_port_teardown(&ds->ports[i]); > > Initially I was tempted to fix this by extending the "for" loop to also > cover the port that failed during setup. But this could have potentially > unforeseen consequences unrelated to devlink_port or even other types of > ports than user ports, which I can't really test for. For example, if > for some reason devlink_port_register itself would fail, then > unconditionally unregistering it in dsa_port_teardown would not be a > smart idea. The list might go on. > > So just make dsa_port_setup undo the setup it had done upon failure, and > let the for loop undo the work of setting up the previous ports, which > are guaranteed to be brought up to a consistent state. > > Fixes: 955222ca5281 ("net: dsa: use a single switch statement for port setup") > Signed-off-by: Vladimir Oltean > --- > net/dsa/dsa2.c | 39 +++++++++++++++++++++++++++++---------- > 1 file changed, 29 insertions(+), 10 deletions(-) > > diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c > index f8445fa73448..b501c90aabe4 100644 > --- a/net/dsa/dsa2.c > +++ b/net/dsa/dsa2.c > @@ -259,8 +259,11 @@ static int dsa_port_setup(struct dsa_port *dp) > const unsigned char *id = (const unsigned char *)&dst->index; > const unsigned char len = sizeof(dst->index); > struct devlink_port *dlp = &dp->devlink_port; > + bool dsa_port_link_registered = false; > + bool devlink_port_registered = false; > struct devlink *dl = ds->devlink; > - int err; > + bool dsa_port_enabled = false; > + int err = 0; > > switch (dp->type) { > case DSA_PORT_TYPE_UNUSED: > @@ -272,15 +275,19 @@ static int dsa_port_setup(struct dsa_port *dp) > dp->index, false, 0, id, len); > err = devlink_port_register(dl, dlp, dp->index); > if (err) > - return err; > + break; > + devlink_port_registered = true; > > err = dsa_port_link_register_of(dp); > if (err) > - return err; > + break; > + dsa_port_link_registered = true; > > err = dsa_port_enable(dp, NULL); > if (err) > - return err; > + break; > + dsa_port_enabled = true; > + > break; > case DSA_PORT_TYPE_DSA: > memset(dlp, 0, sizeof(*dlp)); > @@ -288,15 +295,19 @@ static int dsa_port_setup(struct dsa_port *dp) > dp->index, false, 0, id, len); > err = devlink_port_register(dl, dlp, dp->index); > if (err) > - return err; > + break; > + devlink_port_registered = true; > > err = dsa_port_link_register_of(dp); > if (err) > - return err; > + break; > + dsa_port_link_registered = true; > > err = dsa_port_enable(dp, NULL); > if (err) > - return err; > + break; > + dsa_port_enabled = true; > + > break; > case DSA_PORT_TYPE_USER: > memset(dlp, 0, sizeof(*dlp)); > @@ -304,18 +315,26 @@ static int dsa_port_setup(struct dsa_port *dp) > dp->index, false, 0, id, len); > err = devlink_port_register(dl, dlp, dp->index); > if (err) > - return err; > + break; > + devlink_port_registered = true; > > dp->mac = of_get_mac_address(dp->dn); > err = dsa_slave_create(dp); > if (err) > - return err; > + break; > > devlink_port_type_eth_set(dlp, dp->slave); > break; > } > > - return 0; > + if (err && dsa_port_enabled) > + dsa_port_disable(dp); > + if (err && dsa_port_link_registered) > + dsa_port_link_unregister_of(dp); > + if (err && devlink_port_registered) > + devlink_port_unregister(dlp); > + > + return err; > } No no, I'm pretty sure you can tell this is going to be a nightmare to maintain these boolean states for all port types ;-) And this is not a proper fix for the problem you've spotted. The problem you've spotted is that devlink_port_unregister isn't called for the current port if its setup failed, because dsa_port_teardown -- which is supposed to be called unconditionally on error -- isn't called for the current port. Your first attempt was correct, simply fix the loop in dsa_tree_setup_switches to include the current port: ports_teardown: - for (i = 0; i < port; i++) + for (i = 0; i <= port; i++) As for devlink_port_unregister, most kernel APIs unregistering objects are self protected, so I'm tempted to propose the following patch for devlink: diff --git a/net/core/devlink.c b/net/core/devlink.c index 650f36379203..ab95607800d6 100644 --- a/net/core/devlink.c +++ b/net/core/devlink.c @@ -6264,6 +6264,8 @@ void devlink_port_unregister(struct devlink_port *devlink_port) { struct devlink *devlink = devlink_port->devlink; + if (!devlink_port->registered) + return; devlink_port_type_warn_cancel(devlink_port); devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_DEL); mutex_lock(&devlink->lock); Otherwise we can protect the devlink port unregistering ourselves with: if (dlp->registered) devlink_port_unregister(dlp); BTW that is the subtlety between "unregister" which considers that the object _may_ have been registered, and "deregister" which assumes the object _was_ registered. Would you like to go ahead and propose the devlink patch? Thanks for pointing this out, Vivien