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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48F4DC761AF for ; Tue, 28 Mar 2023 15:11:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230002AbjC1PLE (ORCPT ); Tue, 28 Mar 2023 11:11:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232398AbjC1PLC (ORCPT ); Tue, 28 Mar 2023 11:11:02 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD406EB6F for ; Tue, 28 Mar 2023 08:10:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 18CEDB81D78 for ; Tue, 28 Mar 2023 15:06:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79CDCC433EF; Tue, 28 Mar 2023 15:06:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680016013; bh=JbMV9MBkzDyg/dcfGJKcF45rPPBnyt8KgL5dFSvLT6c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tjceu9h2SD5JyDNUEA9wVQdsX/2tfXGlSpWY5OfWw2MfnQWQ+cTarKZCKZ6hgBlH5 TQrhs+0tz0vIr8rAAh2ijTpSLKDJw0pRzZTVplojbqrYbVFYrOHkpV+iaOZRjXbumi 1Lv/k2rjOKBNaupckcg3W+wOmWIGkSquiCnu6wc0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Alexander Sverdlin , Sasha Levin Subject: [PATCH 5.15 007/146] tty: serial: fsl_lpuart: fix race on RX DMA shutdown Date: Tue, 28 Mar 2023 16:41:36 +0200 Message-Id: <20230328142602.985714015@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230328142602.660084725@linuxfoundation.org> References: <20230328142602.660084725@linuxfoundation.org> User-Agent: quilt/0.67 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 From: Alexander Sverdlin [ Upstream commit 1be6f2b15f902c02e055ae0b419ca789200473c9 ] >>From time to time DMA completion can come in the middle of DMA shutdown: : : lpuart32_shutdown() lpuart_dma_shutdown() del_timer_sync() lpuart_dma_rx_complete() lpuart_copy_rx_to_tty() mod_timer() lpuart_dma_rx_free() When the timer fires a bit later, sport->dma_rx_desc is NULL: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 pc : lpuart_copy_rx_to_tty+0xcc/0x5bc lr : lpuart_timer_func+0x1c/0x2c Call trace: lpuart_copy_rx_to_tty lpuart_timer_func call_timer_fn __run_timers.part.0 run_timer_softirq __do_softirq __irq_exit_rcu irq_exit handle_domain_irq gic_handle_irq call_on_irq_stack do_interrupt_handler ... To fix this fold del_timer_sync() into lpuart_dma_rx_free() after dmaengine_terminate_sync() to make sure timer will not be re-started in lpuart_copy_rx_to_tty() <= lpuart_dma_rx_complete(). Fixes: 4a8588a1cf86 ("serial: fsl_lpuart: delete timer on shutdown") Cc: stable Signed-off-by: Alexander Sverdlin Link: https://lore.kernel.org/r/20230309134302.74940-2-alexander.sverdlin@siemens.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/fsl_lpuart.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 47097002a6427..ac3c6c1e80ccc 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1308,6 +1308,7 @@ static void lpuart_dma_rx_free(struct uart_port *port) struct dma_chan *chan = sport->dma_rx_chan; dmaengine_terminate_sync(chan); + del_timer_sync(&sport->lpuart_timer); dma_unmap_sg(chan->device->dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE); kfree(sport->rx_ring.buf); sport->rx_ring.tail = 0; @@ -1773,7 +1774,6 @@ static int lpuart32_startup(struct uart_port *port) static void lpuart_dma_shutdown(struct lpuart_port *sport) { if (sport->lpuart_dma_rx_use) { - del_timer_sync(&sport->lpuart_timer); lpuart_dma_rx_free(&sport->port); sport->lpuart_dma_rx_use = false; } @@ -1933,10 +1933,8 @@ lpuart_set_termios(struct uart_port *port, struct ktermios *termios, * Since timer function acqures sport->port.lock, need to stop before * acquring same lock because otherwise del_timer_sync() can deadlock. */ - if (old && sport->lpuart_dma_rx_use) { - del_timer_sync(&sport->lpuart_timer); + if (old && sport->lpuart_dma_rx_use) lpuart_dma_rx_free(&sport->port); - } spin_lock_irqsave(&sport->port.lock, flags); @@ -2171,10 +2169,8 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, * Since timer function acqures sport->port.lock, need to stop before * acquring same lock because otherwise del_timer_sync() can deadlock. */ - if (old && sport->lpuart_dma_rx_use) { - del_timer_sync(&sport->lpuart_timer); + if (old && sport->lpuart_dma_rx_use) lpuart_dma_rx_free(&sport->port); - } spin_lock_irqsave(&sport->port.lock, flags); @@ -2870,7 +2866,6 @@ static int __maybe_unused lpuart_suspend(struct device *dev) * Rx DMA path before suspend and start Rx DMA path on resume. */ if (irq_wake) { - del_timer_sync(&sport->lpuart_timer); lpuart_dma_rx_free(&sport->port); } -- 2.39.2