From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759212Ab1KWAks (ORCPT ); Tue, 22 Nov 2011 19:40:48 -0500 Received: from cantor2.suse.de ([195.135.220.15]:42824 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757256Ab1KWAkp (ORCPT ); Tue, 22 Nov 2011 19:40:45 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Tue Nov 22 16:24:06 2011 Message-Id: <20111123002406.394797983@clark.kroah.org> User-Agent: quilt/0.48-20.1.2 Date: Tue, 22 Nov 2011 16:23:26 -0800 From: Greg KH 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 , Alan Cox Subject: [19/53] pch_uart: Fix DMA resource leak issue In-Reply-To: <20111123002419.GA8531@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tomoya MORINAGA commit 90f04c2926cfb5bf74533b0a7766bc896f6a0c0e upstream. Changing UART mode PIO->DMA->PIO->DMA like below, pch_uart driver can't get DMA channel resource. setserial /dev/ttyPCH0 ^low_latency setserial /dev/ttyPCH0 low_latency CAUSE: Changing mode using setserial command, ".startup" function which gets DMA channel is called before ".verify_port" function which sets dma-flag(use_dma/use_dma_flag) as 1. PIO->DMA .startup: Since dma-flag is 0, DMA channel is not requested. .verify_port: dma-flag is set as 1. .shutdown: N/A DMA->PIO .startup: Since dma-flag is 1, DMA channel is requested. .verify_port: dma-flag is set as 0. .shutdown: Since dma-flag is 0, DMA channel is not released. This means DMA channel resource leak occurs. Next time, this driver can't get DMA channel resource forever. MODIFICATION: Currently, when release DMA channel resource, this driver checks dma-flag. However, this specification occurs the above issue. This driver must check whether dma_request_channel is executed or not. The values are saved in private data variable "chan_tx/chan_tx". These variables mean if the value is NULL, DMA channel is not requested, if not NULL, DMA channel is requested. This patch fixes the issue. Signed-off-by: Tomoya MORINAGA Acked-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/pch_uart.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/serial/pch_uart.c +++ b/drivers/tty/serial/pch_uart.c @@ -625,6 +625,7 @@ static void pch_request_dma(struct uart_ dev_err(priv->port.dev, "%s:dma_request_channel FAILS(Rx)\n", __func__); dma_release_channel(priv->chan_tx); + priv->chan_tx = NULL; return; } @@ -1212,8 +1213,7 @@ static void pch_uart_shutdown(struct uar dev_err(priv->port.dev, "pch_uart_hal_set_fifo Failed(ret=%d)\n", ret); - if (priv->use_dma_flag) - pch_free_dma(port); + pch_free_dma(port); free_irq(priv->port.irq, priv); }