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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 8BA1FC433F5 for ; Tue, 4 Sep 2018 20:32:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38FD8206BA for ; Tue, 4 Sep 2018 20:32:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 38FD8206BA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727105AbeIEA66 (ORCPT ); Tue, 4 Sep 2018 20:58:58 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:48265 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725825AbeIEA6z (ORCPT ); Tue, 4 Sep 2018 20:58:55 -0400 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1fxHzb-00077z-4z; Tue, 04 Sep 2018 22:32:07 +0200 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1fxHzZ-0003VB-FR; Tue, 04 Sep 2018 22:32:05 +0200 Date: Tue, 4 Sep 2018 22:32:05 +0200 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Anson Huang Cc: gregkh@linuxfoundation.org, jslaby@suse.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Linux-imx@nxp.com Subject: Re: [PATCH 1/2] tty: serial: imx: add lock for registers save/restore Message-ID: <20180904203205.yboqvzkkrm6g7go5@pengutronix.de> References: <1533809169-24133-1-git-send-email-Anson.Huang@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1533809169-24133-1-git-send-email-Anson.Huang@nxp.com> User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 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-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, Aug 09, 2018 at 06:06:08PM +0800, Anson Huang wrote: > In noirq suspend/resume stage with no_console_suspend enabled, > .imx_console_write() may be called to print out log_buf > message by .printk(), so there will be race condition between > .imx_console_write() and .serial_imx_save/restore_context(), > need to add lock to protect the registers save/restore operations. The function names changes some time ago. Also I'd drop the leading dots in the names which I would understand as members in a struct. Is this a theoretical issue, or did you see actual breakage? > Signed-off-by: Anson Huang > --- > drivers/tty/serial/imx.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c > index 239c0fa..a09ccef 100644 > --- a/drivers/tty/serial/imx.c > +++ b/drivers/tty/serial/imx.c > @@ -2376,9 +2376,12 @@ static int imx_uart_remove(struct platform_device *pdev) > > static void imx_uart_restore_context(struct imx_port *sport) > { > + unsigned long flags; > + > if (!sport->context_saved) > return; Is it safe to check .context_saved without holding the lock? > + spin_lock_irqsave(&sport->port.lock, flags); > imx_uart_writel(sport, sport->saved_reg[4], UFCR); > imx_uart_writel(sport, sport->saved_reg[5], UESC); > imx_uart_writel(sport, sport->saved_reg[6], UTIM); > @@ -2390,11 +2393,15 @@ static void imx_uart_restore_context(struct imx_port *sport) > imx_uart_writel(sport, sport->saved_reg[2], UCR3); > imx_uart_writel(sport, sport->saved_reg[3], UCR4); > sport->context_saved = false; > + spin_unlock_irqrestore(&sport->port.lock, flags); > } > > static void imx_uart_save_context(struct imx_port *sport) > { > + unsigned long flags; > + > /* Save necessary regs */ > + spin_lock_irqsave(&sport->port.lock, flags); > sport->saved_reg[0] = imx_uart_readl(sport, UCR1); > sport->saved_reg[1] = imx_uart_readl(sport, UCR2); > sport->saved_reg[2] = imx_uart_readl(sport, UCR3); > @@ -2406,6 +2413,7 @@ static void imx_uart_save_context(struct imx_port *sport) > sport->saved_reg[8] = imx_uart_readl(sport, UBMR); > sport->saved_reg[9] = imx_uart_readl(sport, IMX21_UTS); > sport->context_saved = true; > + spin_unlock_irqrestore(&sport->port.lock, flags); > } > > static void imx_uart_enable_wakeup(struct imx_port *sport, bool on) Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |