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 2F727C6FD1D for ; Mon, 20 Mar 2023 09:12:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230210AbjCTJME (ORCPT ); Mon, 20 Mar 2023 05:12:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229913AbjCTJMD (ORCPT ); Mon, 20 Mar 2023 05:12:03 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D982012F2A for ; Mon, 20 Mar 2023 02:12:01 -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 6E937B80DB2 for ; Mon, 20 Mar 2023 09:12:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF99FC433D2; Mon, 20 Mar 2023 09:11:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1679303519; bh=Kw2w5QKS/J731Xd0o1Szks+OGaocsvUKrUVvXkUJBnU=; h=Subject:To:Cc:From:Date:From; b=BzI7ivTe/gRY5f1IXCmeZYDug8F2vGLjSPtCijI7H+LchcxqO60XRRsid8bhWsPFa 9w9xxN9TujAFCua5jeNd7xW/AZqs4uD2qkuyumecX3awIcuO70GTfo2rV18O9WfHRQ iG5+qisykMtSo9noSzk9zyYiAUIXU50KL4Flg76w= Subject: FAILED: patch "[PATCH] tty: serial: fsl_lpuart: fix race on RX DMA shutdown" failed to apply to 6.1-stable tree To: alexander.sverdlin@siemens.com, gregkh@linuxfoundation.org, stable@kernel.org Cc: From: Date: Mon, 20 Mar 2023 10:11:51 +0100 Message-ID: <167930351118194@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 1be6f2b15f902c02e055ae0b419ca789200473c9 # git commit -s git send-email --to '' --in-reply-to '167930351118194@kroah.com' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 1be6f2b15f90 ("tty: serial: fsl_lpuart: fix race on RX DMA shutdown") 8682ab0eea89 ("tty: serial: fsl_lpuart: switch to new dmaengine_terminate_* API") 4f5cb8c5e915 ("tty: serial: fsl_lpuart: enable wakeup source for lpuart") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 1be6f2b15f902c02e055ae0b419ca789200473c9 Mon Sep 17 00:00:00 2001 From: Alexander Sverdlin Date: Thu, 9 Mar 2023 14:43:02 +0100 Subject: [PATCH] tty: serial: fsl_lpuart: fix race on RX DMA shutdown >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 diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index f9e164abf920..56e6ba3250cd 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1354,6 +1354,7 @@ 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; @@ -1813,7 +1814,6 @@ 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; } @@ -1973,10 +1973,8 @@ 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); @@ -2210,10 +2208,8 @@ 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); @@ -3020,7 +3016,6 @@ static int lpuart_suspend(struct device *dev) * cannot resume as expected, hence gracefully release the * Rx DMA path before suspend and start Rx DMA path on resume. */ - del_timer_sync(&sport->lpuart_timer); lpuart_dma_rx_free(&sport->port); /* Disable Rx DMA to use UART port as wakeup source */