Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754333Ab3F1DLz (ORCPT ); Thu, 27 Jun 2013 23:11:55 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:10003 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753972Ab3F1DLx (ORCPT ); Thu, 27 Jun 2013 23:11:53 -0400 From: Yijing Wang To: Greg Kroah-Hartman CC: , Liang Li , Yijing Wang , Subject: [PATCH 3.4 stable][PATCH] pch_uart: fix a deadlock when pch_uart as console Date: Fri, 28 Jun 2013 11:10:39 +0800 Message-ID: <1372389039-29524-1-git-send-email-wangyijing@huawei.com> X-Mailer: git-send-email 1.7.11.msysgit.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.135.76.69] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2870 Lines: 85 From: Liang Li commit 384e301e3519599b000c1a2ecd938b533fc15d85 upstream When we use pch_uart as system console like 'console=ttyPCH0,115200', then 'send break' to it. We'll encounter the deadlock on a cpu/core, with interrupts disabled on the core. When we happen to have all irqs affinity to cpu0 then the deadlock on cpu0 actually deadlock whole system. In pch_uart_interrupt, we have spin_lock_irqsave(&priv->lock, flags) then call pch_uart_err_ir when break is received. Then the call to dev_err would actually call to pch_console_write then we'll run into another spin_lock(&priv->lock), with interrupts disabled. So in the call sequence lead by pch_uart_interrupt, we should be carefully to call functions that will 'print message to console' only in case the uart port is not being used as serial console. Signed-off-by: Liang Li Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yijing Wang Cc: stable@vger.kernel.org --- drivers/tty/serial/pch_uart.c | 29 ++++++++++++++++++++++------- 1 files changed, 22 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c index 8b40a1f..10e1a95 100644 --- a/drivers/tty/serial/pch_uart.c +++ b/drivers/tty/serial/pch_uart.c @@ -1024,22 +1024,37 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv) static void pch_uart_err_ir(struct eg20t_port *priv, unsigned int lsr) { u8 fcr = ioread8(priv->membase + UART_FCR); + struct uart_port *port = &priv->port; + struct tty_struct *tty = tty_port_tty_get(&port->state->port); + char *error_msg[5] = {}; + int i = 0; /* Reset FIFO */ fcr |= UART_FCR_CLEAR_RCVR; iowrite8(fcr, priv->membase + UART_FCR); if (lsr & PCH_UART_LSR_ERR) - dev_err(&priv->pdev->dev, "Error data in FIFO\n"); + error_msg[i++] = "Error data in FIFO\n"; + + if (lsr & UART_LSR_FE) { + port->icount.frame++; + error_msg[i++] = " Framing Error\n"; + } - if (lsr & UART_LSR_FE) - dev_err(&priv->pdev->dev, "Framing Error\n"); + if (lsr & UART_LSR_PE) { + port->icount.parity++; + error_msg[i++] = " Parity Error\n"; + } - if (lsr & UART_LSR_PE) - dev_err(&priv->pdev->dev, "Parity Error\n"); + if (lsr & UART_LSR_OE) { + port->icount.overrun++; + error_msg[i++] = " Overrun Error\n"; + } - if (lsr & UART_LSR_OE) - dev_err(&priv->pdev->dev, "Overrun Error\n"); + if (tty == NULL) { + for (i = 0; error_msg[i] != NULL; i++) + dev_err(&priv->pdev->dev, error_msg[i]); + } } static irqreturn_t pch_uart_interrupt(int irq, void *dev_id) -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/