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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 C2165C2D0CE for ; Fri, 27 Dec 2019 18:17:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A0A3021927 for ; Fri, 27 Dec 2019 18:17:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577470645; bh=KQUacGwDkWLuijj1e3YKci1uj1889QRnXqZ6x3PvBYQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bcWe1gReSAm0rr3orfPFUzSjtuwiC1PrtymRL8mJZPDN2SJuQvw2fx4reRozhdCRb cX4+8MQChoOdG/O7AJsa0shTerGA6VMGM8KeZG0R/L+v0Ugg32oBQTd+9c2en/sRTc STFhA0+U+hcqFuvVyp5FmaxLpYtb8pUNy6e7Kysg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728148AbfL0SQC (ORCPT ); Fri, 27 Dec 2019 13:16:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:41116 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728140AbfL0SQB (ORCPT ); Fri, 27 Dec 2019 13:16:01 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3A9FE21582; Fri, 27 Dec 2019 18:16:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577470561; bh=KQUacGwDkWLuijj1e3YKci1uj1889QRnXqZ6x3PvBYQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=thW6gt99qrNI3F/40bbe9d6bMAO5JD6n7vHxQSx/7sw4f9TRKr0Wd1oCwBdcD3du/ JhSpg64d/uCWSqmHOeyfC9p3d4/fHaDQzJTMMQMjsRzo9B44CA+lBxqigFu5kKDIWb 5toCBwppHiZdOmXHP+wcWIdUl/YlaxvI2B44ewbY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Leo Yan , Jeffrey Hugo , Greg Kroah-Hartman , Sasha Levin , linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org Subject: [PATCH AUTOSEL 4.4 09/25] tty: serial: msm_serial: Fix lockup for sysrq and oops Date: Fri, 27 Dec 2019 13:15:33 -0500 Message-Id: <20191227181549.8040-9-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191227181549.8040-1-sashal@kernel.org> References: <20191227181549.8040-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org From: Leo Yan [ Upstream commit 0e4f7f920a5c6bfe5e851e989f27b35a0cc7fb7e ] As the commit 677fe555cbfb ("serial: imx: Fix recursive locking bug") has mentioned the uart driver might cause recursive locking between normal printing and the kernel debugging facilities (e.g. sysrq and oops). In the commit it gave out suggestion for fixing recursive locking issue: "The solution is to avoid locking in the sysrq case and trylock in the oops_in_progress case." This patch follows the suggestion (also used the exactly same code with other serial drivers, e.g. amba-pl011.c) to fix the recursive locking issue, this can avoid stuck caused by deadlock and print out log for sysrq and oops. Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.") Signed-off-by: Leo Yan Reviewed-by: Jeffrey Hugo Link: https://lore.kernel.org/r/20191127141544.4277-2-leo.yan@linaro.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/msm_serial.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 03cac2183579..1a4df5005aec 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -1381,6 +1381,7 @@ static void __msm_console_write(struct uart_port *port, const char *s, int num_newlines = 0; bool replaced = false; void __iomem *tf; + int locked = 1; if (is_uartdm) tf = port->membase + UARTDM_TF; @@ -1393,7 +1394,13 @@ static void __msm_console_write(struct uart_port *port, const char *s, num_newlines++; count += num_newlines; - spin_lock(&port->lock); + if (port->sysrq) + locked = 0; + else if (oops_in_progress) + locked = spin_trylock(&port->lock); + else + spin_lock(&port->lock); + if (is_uartdm) msm_reset_dm_count(port, count); @@ -1429,7 +1436,9 @@ static void __msm_console_write(struct uart_port *port, const char *s, iowrite32_rep(tf, buf, 1); i += num_chars; } - spin_unlock(&port->lock); + + if (locked) + spin_unlock(&port->lock); } static void msm_console_write(struct console *co, const char *s, -- 2.20.1