From patchwork Fri Apr 16 14:05:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 423065 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 3E314C43460 for ; Fri, 16 Apr 2021 14:11:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2794A610F7 for ; Fri, 16 Apr 2021 14:11:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244365AbhDPOMF (ORCPT ); Fri, 16 Apr 2021 10:12:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:53916 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244150AbhDPOLx (ORCPT ); Fri, 16 Apr 2021 10:11:53 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CC27F610FC; Fri, 16 Apr 2021 14:11:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618582288; bh=sCFrgohLIfm8pELW6QsrCxvsgUhRMPjg/ZK7BxCTQQk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cYo7+Us2pq2cbiKNwLiTp6fHKrOg2bU3kWgYhxNN5vd1hgosIzRUAKNnhj+MWSRVh 6Ifx+TzCgKvhpE9UCQ+x7JvPzZv3s+o+PySSs9dMJPWubwtZ5o1bwUN8gvBuhwHdRC FbXdR3NWY+OOjFUsSb1bGnNrOupNloDC3okntwTFafB74WlWYwzffDbDfHEzhaccL/ 5wrBZgk9ibMgOAeACNcZm2CAC5E1heC3aPbaxIFYNtpY9xJ32Iz95kb17iuWkSd/Mf NLtYBms6uw7drrHdGtbmNLxy2kAgJ6a56E5dPzQtiBvlcA3zxgEYaBrSlPccuiF9/b Y6tD8MoyzjxCg== Received: from johan by xi.lan with local (Exim 4.93.0.4) (envelope-from ) id 1lXPBx-0006aC-Gh; Fri, 16 Apr 2021 16:11:29 +0200 From: Johan Hovold To: Greg Kroah-Hartman Cc: Jiri Slaby , Maxime Coquelin , Alexandre Torgue , dillon.minfei@gmail.com, Erwan Le Ray , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold , stable@vger.kernel.org, Alexandre TORGUE , Gerald Baeza Subject: [PATCH 2/3] serial: stm32: fix threaded interrupt handling Date: Fri, 16 Apr 2021 16:05:56 +0200 Message-Id: <20210416140557.25177-3-johan@kernel.org> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20210416140557.25177-1-johan@kernel.org> References: <20210416140557.25177-1-johan@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org When DMA is enabled the receive handler runs in a threaded handler, but the primary handler up until very recently neither disabled interrupts in the device or used IRQF_ONESHOT. This would lead to a deadlock if an interrupt comes in while the threaded receive handler is running under the port lock. Commit ad7676812437 ("serial: stm32: fix a deadlock condition with wakeup event") claimed to fix an unrelated deadlock, but unfortunately also disabled interrupts in the threaded handler. While this prevents the deadlock mentioned in the previous paragraph it also defeats the purpose of using a threaded handler in the first place. Fix this by making the interrupt one-shot and not disabling interrupts in the threaded handler. Note that (receive) DMA must not be used for a console port as the threaded handler could be interrupted while holding the port lock, something which could lead to a deadlock in case an interrupt handler ends up calling printk. Fixes: ad7676812437 ("serial: stm32: fix a deadlock condition with wakeup event") Fixes: 3489187204eb ("serial: stm32: adding dma support") Cc: stable@vger.kernel.org # 4.9 Cc: Alexandre TORGUE Cc: Gerald Baeza Signed-off-by: Johan Hovold Reviewed-by: Valentin Caron --- drivers/tty/serial/stm32-usart.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 4d277804c63e..3524ed2c0c73 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -214,14 +214,11 @@ 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, flags; + unsigned long c; u32 sr; char flag; - if (threaded) - spin_lock_irqsave(&port->lock, flags); - else - spin_lock(&port->lock); + spin_lock(&port->lock); while (stm32_usart_pending_rx(port, &sr, &stm32_port->last_res, threaded)) { @@ -278,10 +275,7 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool threaded) uart_insert_char(port, sr, USART_SR_ORE, c, flag); } - if (threaded) - spin_unlock_irqrestore(&port->lock, flags); - else - spin_unlock(&port->lock); + spin_unlock(&port->lock); tty_flip_buffer_push(tport); } @@ -667,7 +661,8 @@ static int stm32_usart_startup(struct uart_port *port) ret = request_threaded_irq(port->irq, stm32_usart_interrupt, stm32_usart_threaded_interrupt, - IRQF_NO_SUSPEND, name, port); + IRQF_ONESHOT | IRQF_NO_SUSPEND, + name, port); if (ret) return ret; @@ -1156,6 +1151,13 @@ static int stm32_usart_of_dma_rx_probe(struct stm32_port *stm32port, struct dma_async_tx_descriptor *desc = NULL; int ret; + /* + * Using DMA and threaded handler for the console could lead to + * deadlocks. + */ + if (uart_console(port)) + return -ENODEV; + /* Request DMA RX channel */ stm32port->rx_ch = dma_request_slave_channel(dev, "rx"); if (!stm32port->rx_ch) {