Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758309Ab2EIG0x (ORCPT ); Wed, 9 May 2012 02:26:53 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:38791 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755586Ab2EIFw6 (ORCPT ); Wed, 9 May 2012 01:52:58 -0400 Message-Id: <20120509055033.426055874@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Wed, 09 May 2012 06:50:57 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Tomoya MORINAGA , Greg Kroah-Hartman Subject: [ 028/167] [PATCH] pch_uart: Fix dma channel unallocated issue In-Reply-To: <20120509055029.588587017@decadent.org.uk> X-SA-Exim-Connect-IP: 192.168.4.185 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1862 Lines: 63 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tomoya MORINAGA commit af6d17cdc8c89aeb3101f0d27cd32fc0592b40b2 upstream. This driver anticipates pch_uart_verify_port() is not called during installation. However, actually pch_uart_verify_port() is called during installation. As a result, memory access violation occurs like below. 0. initial value: use_dma=0 1. starup() - dma channel is not allocated because use_dma=0 2. pch_uart_verify_port() - Set use_dma=1 3. UART processing acts DMA mode because use_dma=1 - memory access violation occurs! This patch fixes the issue. Solution: Whenever pch_uart_verify_port() is called and then dma channel is not allocated, the channel should be allocated. Signed-off-by: Tomoya MORINAGA Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- drivers/tty/serial/pch_uart.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c index bbbec4a..c2816f4 100644 --- a/drivers/tty/serial/pch_uart.c +++ b/drivers/tty/serial/pch_uart.c @@ -1447,9 +1447,11 @@ static int pch_uart_verify_port(struct uart_port *port, __func__); return -EOPNOTSUPP; #endif - priv->use_dma = 1; priv->use_dma_flag = 1; dev_info(priv->port.dev, "PCH UART : Use DMA Mode\n"); + if (!priv->use_dma) + pch_request_dma(port); + priv->use_dma = 1; } return 0; -- 1.7.10 -- 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/