From patchwork Wed May 12 14:44:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 438623 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 AB83CC43462 for ; Wed, 12 May 2021 15:21:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7376461C85 for ; Wed, 12 May 2021 15:21:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232477AbhELPWK (ORCPT ); Wed, 12 May 2021 11:22:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:60306 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234629AbhELPUH (ORCPT ); Wed, 12 May 2021 11:20:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8C0C2619A3; Wed, 12 May 2021 15:08:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620832092; bh=4CyxnMvVLxRt5bRTu4GPSWoOUFR5aL5t4joZXO2w+PM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CrI4b69weaMiwOE44jj8GK760xk6eZAsH75f5PnaLzMBWA/nILRieP3d/Btg2lF0A r5MzDGMWXysI++/eeOTnQKhyDpb7tL74Kzb3LYsDZfHs5JEhsQSHLdCY56cDuynQK4 U9gUGdlFgx51obhp6qc18kr1h+VvhmBKMeunr+TM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Erwan Le Ray , Sasha Levin Subject: [PATCH 5.10 137/530] serial: stm32: fix a deadlock in set_termios Date: Wed, 12 May 2021 16:44:07 +0200 Message-Id: <20210512144824.323816400@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144819.664462530@linuxfoundation.org> References: <20210512144819.664462530@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Erwan Le Ray [ Upstream commit 436c97936001776f16153771ee887f125443e974 ] CTS/RTS GPIOs support that has been added recently to STM32 UART driver has introduced scheduled code in a set_termios part protected by a spin lock. This generates a potential deadlock scenario: Chain exists of: &irq_desc_lock_class --> console_owner --> &port_lock_key Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&port_lock_key); lock(console_owner); lock(&port_lock_key); lock(&irq_desc_lock_class); *** DEADLOCK *** 4 locks held by stty/766: Move the scheduled code after the spinlock. Fixes: 6cf61b9bd7cc ("tty: serial: Add modem control gpio support for STM32 UART") Signed-off-by: Erwan Le Ray Link: https://lore.kernel.org/r/20210304162308.8984-8-erwan.leray@foss.st.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/stm32-usart.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 85e9a4d4e91d..44522ddc7e6d 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -827,12 +827,6 @@ static void stm32_usart_set_termios(struct uart_port *port, cr3 |= USART_CR3_CTSE | USART_CR3_RTSE; } - /* Handle modem control interrupts */ - if (UART_ENABLE_MS(port, termios->c_cflag)) - stm32_usart_enable_ms(port); - else - stm32_usart_disable_ms(port); - usartdiv = DIV_ROUND_CLOSEST(port->uartclk, baud); /* @@ -914,6 +908,12 @@ static void stm32_usart_set_termios(struct uart_port *port, stm32_usart_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit)); spin_unlock_irqrestore(&port->lock, flags); + + /* Handle modem control interrupts */ + if (UART_ENABLE_MS(port, termios->c_cflag)) + stm32_usart_enable_ms(port); + else + stm32_usart_disable_ms(port); } static const char *stm32_usart_type(struct uart_port *port)