From patchwork Tue Jul 2 11:07:33 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 256379 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id E3B722C00A0 for ; Tue, 2 Jul 2013 21:11:15 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UtyUG-00045w-MY; Tue, 02 Jul 2013 11:11:08 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UtyRu-0002pv-AL for kernel-team@lists.ubuntu.com; Tue, 02 Jul 2013 11:08:42 +0000 Received: from bl20-124-73.dsl.telepac.pt ([2.81.124.73] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UtyRt-0000lM-6i; Tue, 02 Jul 2013 11:08:41 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 45/50] pch_uart: fix a deadlock when pch_uart as console Date: Tue, 2 Jul 2013 12:07:33 +0100 Message-Id: <1372763258-20664-46-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1372763258-20664-1-git-send-email-luis.henriques@canonical.com> References: <1372763258-20664-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Cc: Yijing Wang , Greg Kroah-Hartman , Liang Li X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.5.7.16 -stable review patch. If anyone has any objections, please let me know. ------------------ 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 Cc: Yijing Wang Signed-off-by: Luis Henriques --- drivers/tty/serial/pch_uart.c | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c index 558ce85..4798e94 100644 --- a/drivers/tty/serial/pch_uart.c +++ b/drivers/tty/serial/pch_uart.c @@ -1034,22 +1034,37 @@ 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) - dev_err(&priv->pdev->dev, "Framing Error\n"); + if (lsr & UART_LSR_FE) { + port->icount.frame++; + error_msg[i++] = " Framing Error\n"; + } - if (lsr & UART_LSR_PE) - dev_err(&priv->pdev->dev, "Parity Error\n"); + if (lsr & UART_LSR_PE) { + port->icount.parity++; + error_msg[i++] = " Parity Error\n"; + } - if (lsr & UART_LSR_OE) - dev_err(&priv->pdev->dev, "Overrun Error\n"); + if (lsr & UART_LSR_OE) { + port->icount.overrun++; + error_msg[i++] = " 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)