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authorTomoya MORINAGA <tomoya.rohm@gmail.com>2011-11-11 10:55:27 +0900
committerGreg Kroah-Hartman <gregkh@suse.de>2011-11-15 12:13:43 -0800
commit90f04c2926cfb5bf74533b0a7766bc896f6a0c0e (patch)
tree36f4a4e1c0381ce5ac5217e35e437e43c529fc27 /drivers/tty
parent604fdb75094a7367e1794fd0f62183380364ce13 (diff)
pch_uart: Fix DMA resource leak issue
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 <tomoya.rohm@gmail.com> Acked-by: Alan Cox <alan@linux.intel.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/pch_uart.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index ac852b5a8f93..d6aba8c087e4 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -632,6 +632,7 @@ static void pch_request_dma(struct uart_port *port)
dev_err(priv->port.dev, "%s:dma_request_channel FAILS(Rx)\n",
__func__);
dma_release_channel(priv->chan_tx);
+ priv->chan_tx = NULL;
return;
}
@@ -1219,8 +1220,7 @@ static void pch_uart_shutdown(struct uart_port *port)
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);
}