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=-14.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,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 9E9BAC2D0A3 for ; Thu, 12 Nov 2020 08:32:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F9E8221FE for ; Thu, 12 Nov 2020 08:32:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="NBQZsI3D" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725928AbgKLIc3 (ORCPT ); Thu, 12 Nov 2020 03:32:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:52232 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725898AbgKLIc3 (ORCPT ); Thu, 12 Nov 2020 03:32:29 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D51E52100A; Thu, 12 Nov 2020 08:32:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605169947; bh=PGcwZi5pJfL3iqKH7au9+Ilu3JqjdxaLjxs8Rk63fxg=; h=Subject:To:From:Date:From; b=NBQZsI3DZMpz/gFZTamtyfDlfovWgvbTB7m08ZJtUku8llmg5su8ETVPfqrSbM2DR lFxWbaTVioPOt6NLjIRq4pMwQMa/yiRpYnVzKmUKP0iZOCvt0ffmVx7ZMNNWWbVVnc GJ5w9dDqBpyplS1Av+LXFWPDf8LbqVOdC7mlS0DM= Subject: patch "tty: serial: imx: fix potential deadlock" added to tty-linus To: samuel.nobs@taitradio.com, gregkh@linuxfoundation.org, stable@vger.kernel.org, u.kleine-koenig@pengutronix.de From: Date: Thu, 12 Nov 2020 09:33:26 +0100 Message-ID: <16051700065460@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled tty: serial: imx: fix potential deadlock to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From 33f16855dcb973f745c51882d0e286601ff3be2b Mon Sep 17 00:00:00 2001 From: Sam Nobs Date: Tue, 10 Nov 2020 09:50:06 +1300 Subject: tty: serial: imx: fix potential deadlock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Enabling the lock dependency validator has revealed that the way spinlocks are used in the IMX serial port could result in a deadlock. Specifically, imx_uart_int() acquires a spinlock without disabling the interrupts, meaning that another interrupt could come along and try to acquire the same spinlock, potentially causing the two to wait for each other indefinitely. Use spin_lock_irqsave() instead to disable interrupts upon acquisition of the spinlock. Fixes: c974991d2620 ("tty:serial:imx: use spin_lock instead of spin_lock_irqsave in isr") Reviewed-by: Uwe Kleine-König Signed-off-by: Sam Nobs Link: https://lore.kernel.org/r/1604955006-9363-1-git-send-email-samuel.nobs@taitradio.com Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 1731d9728865..3c53a3c89959 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -942,8 +942,14 @@ static irqreturn_t imx_uart_int(int irq, void *dev_id) struct imx_port *sport = dev_id; unsigned int usr1, usr2, ucr1, ucr2, ucr3, ucr4; irqreturn_t ret = IRQ_NONE; + unsigned long flags = 0; - spin_lock(&sport->port.lock); + /* + * IRQs might not be disabled upon entering this interrupt handler, + * e.g. when interrupt handlers are forced to be threaded. To support + * this scenario as well, disable IRQs when acquiring the spinlock. + */ + spin_lock_irqsave(&sport->port.lock, flags); usr1 = imx_uart_readl(sport, USR1); usr2 = imx_uart_readl(sport, USR2); @@ -1013,7 +1019,7 @@ static irqreturn_t imx_uart_int(int irq, void *dev_id) ret = IRQ_HANDLED; } - spin_unlock(&sport->port.lock); + spin_unlock_irqrestore(&sport->port.lock, flags); return ret; } -- 2.29.2