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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 19538C433E0 for ; Fri, 29 May 2020 11:54:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0297E207F5 for ; Fri, 29 May 2020 11:54:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726509AbgE2Lx7 (ORCPT ); Fri, 29 May 2020 07:53:59 -0400 Received: from mx2.suse.de ([195.135.220.15]:59102 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725865AbgE2Lx5 (ORCPT ); Fri, 29 May 2020 07:53:57 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id B67D9ABBD; Fri, 29 May 2020 11:53:54 +0000 (UTC) Subject: Re: [PATCH 1/1] tty: serial: owl: Initialize lock before registering port To: Greg Kroah-Hartman , Cristian Ciocaltea Cc: Manivannan Sadhasivam , Jiri Slaby , Andy Shevchenko , linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-actions@lists.infradead.org References: <89f6393934fc6d493f8b9e87c1a6e916642b6a18.1590749143.git.cristian.ciocaltea@gmail.com> <20200529113419.GA1631227@kroah.com> From: =?UTF-8?Q?Andreas_F=c3=a4rber?= Organization: SUSE Software Solutions Germany GmbH Message-ID: <4c40d6c1-47e8-b4ec-f2fd-e9767b03630c@suse.de> Date: Fri, 29 May 2020 13:53:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200529113419.GA1631227@kroah.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Am 29.05.20 um 13:34 schrieb Greg Kroah-Hartman: > On Fri, May 29, 2020 at 02:06:47PM +0300, Cristian Ciocaltea wrote: >> Running a lockdep-enabled kernel leads to the following splat when >> probing the owl-uart driver: >> >> [ 1.271784] b0124000.serial: ttyOWL2 at MMIO 0xb0124000 (irq = 22, base_baud = 1500000) is a owl-uart >> [ 1.281226] INFO: trying to register non-static key. >> [ 1.286179] the code is fine but needs lockdep annotation. >> [ 1.291648] turning off the locking correctness validator. >> [ 1.297125] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.7.0-rc7+ #70 >> [ 1.303462] Hardware name: Generic DT based system >> [ 1.308268] [<80111d3c>] (unwind_backtrace) from [<8010c9b8>] (show_stack+0x10/0x14) >> [ 1.316003] [<8010c9b8>] (show_stack) from [<805016b4>] (dump_stack+0xb4/0xe0) >> [ 1.323218] [<805016b4>] (dump_stack) from [<80182dec>] (register_lock_class+0x25c/0x8f4) >> [ 1.331391] [<80182dec>] (register_lock_class) from [<8017ee34>] (__lock_acquire+0xb4/0x2ee4) >> [ 1.339901] [<8017ee34>] (__lock_acquire) from [<8018291c>] (lock_acquire+0x424/0x4c8) >> [ 1.347813] [<8018291c>] (lock_acquire) from [<808597b0>] (_raw_spin_lock_irqsave+0x54/0x68) >> [ 1.356242] [<808597b0>] (_raw_spin_lock_irqsave) from [<80582e94>] (uart_add_one_port+0x384/0x510) >> [ 1.365276] [<80582e94>] (uart_add_one_port) from [<8058b4d0>] (owl_uart_probe+0x1bc/0x248) >> [ 1.373621] [<8058b4d0>] (owl_uart_probe) from [<8059c0e4>] (platform_drv_probe+0x48/0x94) >> [ 1.381874] [<8059c0e4>] (platform_drv_probe) from [<805997c4>] (really_probe+0x200/0x470) >> [ 1.390123] [<805997c4>] (really_probe) from [<80599c80>] (driver_probe_device+0x16c/0x1bc) >> [ 1.398461] [<80599c80>] (driver_probe_device) from [<80599f18>] (device_driver_attach+0x44/0x60) >> [ 1.407317] [<80599f18>] (device_driver_attach) from [<8059a078>] (__driver_attach+0x144/0x14c) >> [ 1.416000] [<8059a078>] (__driver_attach) from [<805978ac>] (bus_for_each_dev+0x5c/0xb4) >> [ 1.424162] [<805978ac>] (bus_for_each_dev) from [<8059896c>] (bus_add_driver+0x118/0x204) >> [ 1.432410] [<8059896c>] (bus_add_driver) from [<8059ae6c>] (driver_register+0xbc/0xf8) >> [ 1.440405] [<8059ae6c>] (driver_register) from [<80c1fd24>] (owl_uart_init+0x20/0x40) >> [ 1.448313] [<80c1fd24>] (owl_uart_init) from [<801021d8>] (do_one_initcall+0x184/0x3a4) >> [ 1.456399] [<801021d8>] (do_one_initcall) from [<80c01100>] (kernel_init_freeable+0x264/0x2e4) >> [ 1.465085] [<80c01100>] (kernel_init_freeable) from [<80850a88>] (kernel_init+0x8/0x110) >> [ 1.473249] [<80850a88>] (kernel_init) from [<80100114>] (ret_from_fork+0x14/0x20) >> [ 1.480800] Exception stack(0xee8bdfb0 to 0xee8bdff8) >> [ 1.485841] dfa0: 00000000 00000000 00000000 00000000 >> [ 1.494002] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >> [ 1.502162] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000 >> [ 1.508914] printk: console [ttyOWL2] enabled >> >> The locking issue occurs in uart_configure_port() when trying to >> guard the call to set_mctrl(). >> >> uart_add_one_port() should normally initialize the spinlock via >> uart_port_spin_lock_init(), but it never happens because the port is >> detected as a console and, as a consequence, the spinlock is expected >> to be already initialized. >> >> The commit a3cb39d258ef >> ("serial: core: Allow detach and attach serial device for console") >> changed the lock initialization logic to assume the spinlock is >> initialized even if the console is not enabled. >> >> Therefore, initialize the lock explicitly in owl_uart_probe(), before >> attempting to invoke uart_add_one_port(). >> >> Fixes: a3cb39d258ef ("serial: core: Allow detach and attach serial device for console") >> Signed-off-by: Cristian Ciocaltea >> --- >> drivers/tty/serial/owl-uart.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c >> index c149f8c30007..c2fa2f15d50a 100644 >> --- a/drivers/tty/serial/owl-uart.c >> +++ b/drivers/tty/serial/owl-uart.c >> @@ -705,6 +705,8 @@ static int owl_uart_probe(struct platform_device *pdev) >> owl_uart_ports[pdev->id] = owl_port; >> platform_set_drvdata(pdev, owl_port); >> >> + spin_lock_init(&owl_port->port.lock); >> + >> ret = uart_add_one_port(&owl_uart_driver, &owl_port->port); >> if (ret) >> owl_uart_ports[pdev->id] = NULL; > > Ugh, another one :( > > Thanks for this, will queue this up now. Thanks. If this is the expected pattern now, I'll also have to update in-flight patches, such as Sunplus. Regards, Andreas -- SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Felix Imendörffer HRB 36809 (AG Nürnberg)