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[23.128.96.18]) by mx.google.com with ESMTP id el22si6064107ejc.714.2021.02.19.09.52.06; Fri, 19 Feb 2021 09:52:38 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@foss.st.com header.s=selector1 header.b=1RvJsxDY; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=foss.st.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230253AbhBSRu4 (ORCPT + 99 others); Fri, 19 Feb 2021 12:50:56 -0500 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:60638 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S230000AbhBSRsi (ORCPT ); Fri, 19 Feb 2021 12:48:38 -0500 Received: from pps.filterd (m0046661.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 11JHliam024587; Fri, 19 Feb 2021 18:47:47 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=selector1; bh=09/kY+M5hA8Jr80kzo1oUnnWddYqgoiumzAxzpyWSaU=; b=1RvJsxDYAqXuI5c0feWaOwSFOa2sAH45Rvlmk8oMLVYGIOAWriWMVzDGPVVTPUOnXng4 9to3K7bbG2FOfV5KA3MFk75a33YUw2UZB0c9+71HNgd1C9TLb0XO7ThWkCxHXYTLmIeE BG0d6n39YxCKR9Xb7TZv9zcYXDpP/jKhx/Nu5PAxje6lGWe4x5U18mEOlgAtEYCnQl49 YEGt65jG6zRoNlmtkDv8b5G5ztJ13X/UKnMQ00y8m1Zv5NmPJMRQfGVZm0UhX/wWSxaL mQbqau9aVdZrbb7ETILVNwZ3+VSYvZLNGrs50Gb71yVlz4OXs+wEwszVl2RBOVMHalFO iw== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 36p6hq7p34-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 19 Feb 2021 18:47:47 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 24B3710002A; Fri, 19 Feb 2021 18:47:47 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag2node3.st.com [10.75.127.6]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 1927F25F3FC; Fri, 19 Feb 2021 18:47:47 +0100 (CET) Received: from localhost (10.75.127.46) by SFHDAG2NODE3.st.com (10.75.127.6) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 19 Feb 2021 18:47:46 +0100 From: Erwan Le Ray To: Greg Kroah-Hartman , Jiri Slaby , Maxime Coquelin , Alexandre Torgue CC: , , , , Erwan Le Ray , Fabrice Gasnier , Valentin Caron Subject: [PATCH 07/13] serial: stm32: fix a deadlock in set_termios Date: Fri, 19 Feb 2021 18:47:30 +0100 Message-ID: <20210219174736.1022-8-erwan.leray@foss.st.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210219174736.1022-1-erwan.leray@foss.st.com> References: <20210219174736.1022-1-erwan.leray@foss.st.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.75.127.46] X-ClientProxiedBy: SFHDAG1NODE3.st.com (10.75.127.3) To SFHDAG2NODE3.st.com (10.75.127.6) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-19_08:2021-02-18,2021-02-19 signatures=0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 14011183edfe..4ba164820904 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -829,12 +829,6 @@ 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); /* @@ -916,6 +910,12 @@ 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) -- 2.17.1