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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 34546C43381 for ; Tue, 19 Mar 2019 12:18:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F18F213F2 for ; Tue, 19 Mar 2019 12:18:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727727AbfCSMSP (ORCPT ); Tue, 19 Mar 2019 08:18:15 -0400 Received: from foss.arm.com ([217.140.101.70]:50612 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726743AbfCSMSP (ORCPT ); Tue, 19 Mar 2019 08:18:15 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 69DF71596; Tue, 19 Mar 2019 05:18:14 -0700 (PDT) Received: from why.wild-wind.fr.eu.org (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1BF373F59C; Tue, 19 Mar 2019 05:18:12 -0700 (PDT) Date: Tue, 19 Mar 2019 12:18:07 +0000 From: Marc Zyngier To: Heikki Krogerus Cc: Greg Kroah-Hartman , Guenter Roeck , , Subject: Re: [PATCH v2] usb: typec: fusb302: Fix debugfs mutex initialisation Message-ID: <20190319121807.68c858f7@why.wild-wind.fr.eu.org> In-Reply-To: <20190319114511.GS7752@kuha.fi.intel.com> References: <20190318174906.10429-1-marc.zyngier@arm.com> <20190319114511.GS7752@kuha.fi.intel.com> Organization: ARM Ltd X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 19 Mar 2019 13:45:11 +0200 Heikki Krogerus wrote: > On Mon, Mar 18, 2019 at 05:49:06PM +0000, Marc Zyngier wrote: > > Running a kernel with the fusb302 driver and lockdep enabled > > leads to an unpleasant warning: > > > > [ 4.617477] INFO: trying to register non-static key. > > [ 4.617930] the code is fine but needs lockdep annotation. > > [ 4.618418] turning off the locking correctness validator. > > [ 4.618913] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.1.0-rc1-00007-g3542533f3fc9 #13 > > [ 4.619620] Hardware name: rockchip evb_rk3399/evb_rk3399, BIOS 2019.04-rc3-00124-g2feec69fb1 03/15/2019 > > [ 4.620454] Call trace: > > [ 4.620693] dump_backtrace+0x0/0x138 > > [ 4.621028] show_stack+0x24/0x30 > > [ 4.621336] dump_stack+0xbc/0x104 > > [ 4.621649] register_lock_class+0x594/0x598 > > [ 4.622036] __lock_acquire+0x80/0x11b8 > > [ 4.622384] lock_acquire+0xdc/0x260 > > [ 4.622711] __mutex_lock+0x90/0x8a0 > > [ 4.623037] mutex_lock_nested+0x3c/0x50 > > [ 4.623394] _fusb302_log+0x88/0x1f0 > > [ 4.623721] fusb302_log+0x7c/0xa0 > > [ 4.624033] tcpm_init+0x5c/0x190 > > [ 4.624336] tcpm_init+0x3c/0x130 > > [ 4.624640] tcpm_register_port+0x574/0x878 > > [ 4.625019] fusb302_probe+0x2c8/0x590 > > > > Despite what the message says, the code isn't fine, as it tries to > > make use of the fusb302_log facility pretty early. This requires the > > logbuffer_lock mutex to be initialised, but that only happens much > > later. Boo. > > > > Hoist the fusb302_debugfs_init call before tcpm_register_port so that > > we can enjoy a working mutex. At Guenter's request, also add teardown > > of the debugfs facility on the error path. > > > > Signed-off-by: Marc Zyngier > > After applying this there was no more "fusb302" debugfs directory, and > attempt to unload the fusb302 module dead locked. Also, attempt to > reboot caused this to happen on my GDPWin board after applying the > patch: > > BUG: Dentry 0000000012f2a05d{i=149,n=i2c-fusb302} still in use (1) [unmount of sysfs sysfs] > WARNING: CPU: 3 PID: 1639 at fs/dcache.c:1529 umount_check.cold.55+0x2e/0x3a > Modules linked in: intel_xhci_usb_role_switch roles pi3usb30532 typec i915 intel_gtt intel_cht_int33fe [last unloaded: tcpm] > CPU: 3 PID: 1639 Comm: umount Not tainted 5.1.0-rc1-heikki+ #916 > Hardware name: Default string Default string/Default string, BIOS 5.11 05/25/2017 > RIP: 0010:umount_check.cold.55+0x2e/0x3a > ... OK, that's interesting. On my system, I do have the debugfs file: root@city-of-tiny-lites:~# cat /sys/kernel/debug/fusb302/4-0022 [ 4.517682] sw reset [ 4.520379] fusb302 device ID: 0x81 [ 4.523544] pd := off [ 4.523593] vbus is already Off [ 4.523603] charge is already Off [ 4.523615] vconn is already Off [ 4.524274] pd header := Sink, Device [ 4.525948] cc1=Open, cc2=Open [ 4.530345] pd := off [ 4.530378] vbus is already Off [ 4.530388] charge is already Off [ 4.530405] vconn is already Off [ 4.530931] pd header := Sink, Device [ 4.533773] cc := Open [ 4.642347] start drp toggling I don't use any module though, so maybe there is something there. I'll investigate. > Note. Your patch has also a conflict with patches from Hans, I > think with this one: https://patchwork.kernel.org/patch/10847275/ > I can take care of that, but you can also rebase the next version on > top of my typec-next branch to solve that problem: > https://github.com/krohei/linux/commits/typec-next > > I think I need to add that to the MAINTAINERS file. Fair enough. I'll come back once I know what happens here... Thanks, M. -- Without deviation from the norm, progress is not possible.