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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 1B4E7C432C0 for ; Fri, 22 Nov 2019 10:34:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E625120714 for ; Fri, 22 Nov 2019 10:34:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728043AbfKVKeF (ORCPT ); Fri, 22 Nov 2019 05:34:05 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:47611 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727303AbfKVKeF (ORCPT ); Fri, 22 Nov 2019 05:34:05 -0500 Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1iY6GI-0002wX-Nd; Fri, 22 Nov 2019 11:34:02 +0100 Received: from ukl by ptx.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1iY6GF-0003jP-8l; Fri, 22 Nov 2019 11:33:59 +0100 Date: Fri, 22 Nov 2019 11:33:59 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Andy Duan Cc: "gregkh@linuxfoundation.org" , "linux-serial@vger.kernel.org" , "jslaby@suse.com" , "festevam@gmail.com" , kernel@pengutronix.de, Sergey Senozhatsky , Steven Rostedt , Petr Mladek Subject: Re: [PATCH tty/serial 1/1] tty: serial: imx: fix sysrq lockdep issue Message-ID: <20191122103359.fud44lh5wl5d3gxe@pengutronix.de> References: <1574416632-32321-1-git-send-email-fugang.duan@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1574416632-32321-1-git-send-email-fugang.duan@nxp.com> User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-serial@vger.kernel.org Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Hello, On Fri, Nov 22, 2019 at 10:00:53AM +0000, Andy Duan wrote: > From: Fugang Duan > > commit dbdda842fe96 ("printk: Add console owner and waiter logic to > load balance console writes") introduces the lockdep issue for imx > serial driver in sysrq case: > CPU0 CPU1 > ---- ---- > lock(&port_lock_key); > lock(console_owner); > lock(&port_lock_key); > lock(console_owner); > > It should unlock port_lock_key in handle_sysrq(). I already discussed this problem some time ago but then failed to complete the topic. You might want to look at the old discussion, see https://www.spinics.net/lists/kernel/msg3266353.html. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |