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 X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 DD682C43331 for ; Tue, 24 Mar 2020 18:48:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B2B592074D for ; Tue, 24 Mar 2020 18:48:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=walle.cc header.i=@walle.cc header.b="f55ZEELx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727942AbgCXSsV (ORCPT ); Tue, 24 Mar 2020 14:48:21 -0400 Received: from ssl.serverraum.org ([176.9.125.105]:44833 "EHLO ssl.serverraum.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727715AbgCXSsT (ORCPT ); Tue, 24 Mar 2020 14:48:19 -0400 Received: from apollo.fritz.box (unknown [IPv6:2a02:810c:c200:2e91:6257:18ff:fec4:ca34]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id C7CAE23E21; Tue, 24 Mar 2020 19:48:16 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1585075697; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=coDQ3BMYKViIn16BM07LUkgfCh1z1B3hMas8+q9F7Sw=; b=f55ZEELx7JwrXq8N7GdKDqFSn+gYu3SeNb6I2dSyn5zgnq99C6/MDIEAjK52rZENauJTVa VhB1C4dT/ElNuVPBurPT784TQ15z/UrztP1puoudFSc2ngLJlZpYDlgoPZ98W7q4Rq1EfZ Sn4ew/PKsWdDiXqfWjIE9LAtmNKX0Vo= From: Michael Walle To: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jiri Slaby , Greg Kroah-Hartman , Michael Walle , Leonard Crestez Subject: [RFC PATCH 3/3] tty: serial: fsl_lpuart: fix possible console deadlock Date: Tue, 24 Mar 2020 19:47:58 +0100 Message-Id: <20200324184758.8204-3-michael@walle.cc> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200324184758.8204-1-michael@walle.cc> References: <20200324184758.8204-1-michael@walle.cc> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spamd-Bar: ++++ X-Rspamd-Server: web X-Rspamd-Queue-Id: C7CAE23E21 X-Spamd-Result: default: False [4.90 / 15.00]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; R_MISSING_CHARSET(2.50)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; NEURAL_SPAM(0.00)[0.189]; BROKEN_CONTENT_TYPE(1.50)[]; RCPT_COUNT_FIVE(0.00)[6]; DKIM_SIGNED(0.00)[]; MID_CONTAINS_FROM(1.00)[]; RCVD_COUNT_ZERO(0.00)[0]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:31334, ipnet:2a02:810c:8000::/33, country:DE] Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the kernel console output is on this console any dev_{err,warn,info}() may result in a deadlock if the sport->port.lock spinlock is already held. This is because the _console_write() try to aquire this lock, too. Remove any error messages where the spinlock is taken or print after the lock is released. Reported-by: Leonard Crestez Signed-off-by: Michael Walle --- drivers/tty/serial/fsl_lpuart.c | 35 +++++++-------------------------- 1 file changed, 7 insertions(+), 28 deletions(-) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index bbba298b68a4..0910308b38b1 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -420,7 +420,6 @@ static void lpuart_dma_tx(struct lpuart_port *sport) { struct circ_buf *xmit = &sport->port.state->xmit; struct scatterlist *sgl = sport->tx_sgl; - struct device *dev = sport->port.dev; struct dma_chan *chan = sport->dma_tx_chan; int ret; @@ -442,10 +441,8 @@ static void lpuart_dma_tx(struct lpuart_port *sport) ret = dma_map_sg(chan->device->dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE); - if (!ret) { - dev_err(dev, "DMA mapping error for TX.\n"); + if (!ret) return; - } sport->dma_tx_desc = dmaengine_prep_slave_sg(chan, sgl, ret, DMA_MEM_TO_DEV, @@ -453,7 +450,6 @@ static void lpuart_dma_tx(struct lpuart_port *sport) if (!sport->dma_tx_desc) { dma_unmap_sg(chan->device->dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE); - dev_err(dev, "Cannot prepare TX slave DMA!\n"); return; } @@ -520,21 +516,12 @@ static int lpuart_dma_tx_request(struct uart_port *port) struct lpuart_port *sport = container_of(port, struct lpuart_port, port); struct dma_slave_config dma_tx_sconfig = {}; - int ret; dma_tx_sconfig.dst_addr = lpuart_dma_datareg_addr(sport); dma_tx_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; dma_tx_sconfig.dst_maxburst = 1; dma_tx_sconfig.direction = DMA_MEM_TO_DEV; - ret = dmaengine_slave_config(sport->dma_tx_chan, &dma_tx_sconfig); - - if (ret) { - dev_err(sport->port.dev, - "DMA slave config failed, err = %d\n", ret); - return ret; - } - - return 0; + return dmaengine_slave_config(sport->dma_tx_chan, &dma_tx_sconfig); } static bool lpuart_is_32(struct lpuart_port *sport) @@ -1074,8 +1061,8 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport) dmastat = dmaengine_tx_status(chan, sport->dma_rx_cookie, &state); if (dmastat == DMA_ERROR) { - dev_err(sport->port.dev, "Rx DMA transfer failed!\n"); spin_unlock_irqrestore(&sport->port.lock, flags); + dev_err(sport->port.dev, "Rx DMA transfer failed!\n"); return; } @@ -1179,23 +1166,17 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport) sg_init_one(&sport->rx_sgl, ring->buf, sport->rx_dma_rng_buf_len); nent = dma_map_sg(chan->device->dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE); - - if (!nent) { - dev_err(sport->port.dev, "DMA Rx mapping error\n"); + if (!nent) return -EINVAL; - } dma_rx_sconfig.src_addr = lpuart_dma_datareg_addr(sport); dma_rx_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; dma_rx_sconfig.src_maxburst = 1; dma_rx_sconfig.direction = DMA_DEV_TO_MEM; - ret = dmaengine_slave_config(chan, &dma_rx_sconfig); - if (ret < 0) { - dev_err(sport->port.dev, - "DMA Rx slave config failed, err = %d\n", ret); + ret = dmaengine_slave_config(chan, &dma_rx_sconfig); + if (ret < 0) return ret; - } sport->dma_rx_desc = dmaengine_prep_dma_cyclic(chan, sg_dma_address(&sport->rx_sgl), @@ -1203,10 +1184,8 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport) sport->rx_sgl.length / 2, DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT); - if (!sport->dma_rx_desc) { - dev_err(sport->port.dev, "Cannot prepare cyclic DMA\n"); + if (!sport->dma_rx_desc) return -EFAULT; - } sport->dma_rx_desc->callback = lpuart_dma_rx_complete; sport->dma_rx_desc->callback_param = sport; -- 2.20.1