From patchwork Wed May 12 14:43:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 436477 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 8CBF0C2B9FD for ; Wed, 12 May 2021 16:37:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 71B1C611BE for ; Wed, 12 May 2021 16:37:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236964AbhELQhz (ORCPT ); Wed, 12 May 2021 12:37:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:47150 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234679AbhELQ2R (ORCPT ); Wed, 12 May 2021 12:28:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9756261438; Wed, 12 May 2021 15:56:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620834984; bh=ErVlzjerLrMRDf2W80JWhlFN6tgQoqq/H8051ynk2rc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tJlWWnbXD67HdOrt2j26AHiTErYfd371kBypZftr6owPU95GyFu6z8W6jYEWk+sj3 idu6q8AXO23kcVTjHXvO1M5Z98KYtjFv4GEQwSViWJmJi9TrePZuDHIe+mSDdhm6WJ 1V9ebXtrRDza0IjDtMIIDfQOXzaAXtH9Uq/DN7mk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Erwan Le Ray , Fabrice Gasnier , Sasha Levin Subject: [PATCH 5.12 163/677] serial: stm32: fix a deadlock condition with wakeup event Date: Wed, 12 May 2021 16:43:29 +0200 Message-Id: <20210512144842.664477681@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144837.204217980@linuxfoundation.org> References: <20210512144837.204217980@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 ad7676812437a00a4c6be155fc17926069f99084 ] Deadlock issue is seen when enabling CONFIG_PROVE_LOCKING=Y, and uart console as wakeup source. Deadlock occurs when resuming from low power mode if system is waked up via usart console. The deadlock is triggered 100% when also disabling console suspend prior to go to suspend. Simplified call stack, deadlock condition: - stm32_console_write <-- spin_lock already held - print_circular_bug - pm_wakeup_dev_event <-- triggers lockdep as seen above - stm32_receive_chars - stm32_interrupt <-- wakeup via uart console, takes the lock So, revisit spin_lock in stm32-usart driver: - there is no need to hold the lock to access ICR (atomic clear of status flags) - only hold the lock inside stm32_receive_chars() routine (no need to call pm_wakeup_dev_event with lock held) - keep stm32_transmit_chars() routine called with lock held Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver") Signed-off-by: Erwan Le Ray Signed-off-by: Fabrice Gasnier Link: https://lore.kernel.org/r/20210304162308.8984-6-erwan.leray@foss.st.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/stm32-usart.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 223cec70c57c..370141445780 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -214,13 +214,18 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool threaded) struct tty_port *tport = &port->state->port; struct stm32_port *stm32_port = to_stm32_port(port); const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; - unsigned long c; + unsigned long c, flags; u32 sr; char flag; if (irqd_is_wakeup_set(irq_get_irq_data(port->irq))) pm_wakeup_event(tport->tty->dev, 0); + if (threaded) + spin_lock_irqsave(&port->lock, flags); + else + spin_lock(&port->lock); + while (stm32_usart_pending_rx(port, &sr, &stm32_port->last_res, threaded)) { sr |= USART_SR_DUMMY_RX; @@ -276,9 +281,12 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool threaded) uart_insert_char(port, sr, USART_SR_ORE, c, flag); } - spin_unlock(&port->lock); + if (threaded) + spin_unlock_irqrestore(&port->lock, flags); + else + spin_unlock(&port->lock); + tty_flip_buffer_push(tport); - spin_lock(&port->lock); } static void stm32_usart_tx_dma_complete(void *arg) @@ -459,8 +467,6 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; u32 sr; - spin_lock(&port->lock); - sr = readl_relaxed(port->membase + ofs->isr); if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG) @@ -474,10 +480,11 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) if ((sr & USART_SR_RXNE) && !(stm32_port->rx_ch)) stm32_usart_receive_chars(port, false); - if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch)) + if ((sr & USART_SR_TXE) && !(stm32_port->tx_ch)) { + spin_lock(&port->lock); stm32_usart_transmit_chars(port); - - spin_unlock(&port->lock); + spin_unlock(&port->lock); + } if (stm32_port->rx_ch) return IRQ_WAKE_THREAD; @@ -490,13 +497,9 @@ static irqreturn_t stm32_usart_threaded_interrupt(int irq, void *ptr) struct uart_port *port = ptr; struct stm32_port *stm32_port = to_stm32_port(port); - spin_lock(&port->lock); - if (stm32_port->rx_ch) stm32_usart_receive_chars(port, true); - spin_unlock(&port->lock); - return IRQ_HANDLED; }