| From f8fd1b0350d3a4581125f5eda6528f5a2c5f9183 Mon Sep 17 00:00:00 2001 |
| From: Loic Poulain <loic.poulain@intel.com> |
| Date: Thu, 24 Apr 2014 11:34:48 +0200 |
| Subject: serial: 8250: Fix thread unsafe __dma_tx_complete function |
| |
| From: Loic Poulain <loic.poulain@intel.com> |
| |
| commit f8fd1b0350d3a4581125f5eda6528f5a2c5f9183 upstream. |
| |
| __dma_tx_complete is not protected against concurrent |
| call of serial8250_tx_dma. it can lead to circular tail |
| index corruption or parallel call of serial_tx_dma on the |
| same data portion. |
| |
| This patch fixes this issue by holding the port lock. |
| |
| Signed-off-by: Loic Poulain <loic.poulain@intel.com> |
| Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/tty/serial/8250/8250_dma.c | 9 +++++++-- |
| 1 file changed, 7 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/tty/serial/8250/8250_dma.c |
| +++ b/drivers/tty/serial/8250/8250_dma.c |
| @@ -20,12 +20,15 @@ static void __dma_tx_complete(void *para |
| struct uart_8250_port *p = param; |
| struct uart_8250_dma *dma = p->dma; |
| struct circ_buf *xmit = &p->port.state->xmit; |
| - |
| - dma->tx_running = 0; |
| + unsigned long flags; |
| |
| dma_sync_single_for_cpu(dma->txchan->device->dev, dma->tx_addr, |
| UART_XMIT_SIZE, DMA_TO_DEVICE); |
| |
| + spin_lock_irqsave(&p->port.lock, flags); |
| + |
| + dma->tx_running = 0; |
| + |
| xmit->tail += dma->tx_size; |
| xmit->tail &= UART_XMIT_SIZE - 1; |
| p->port.icount.tx += dma->tx_size; |
| @@ -35,6 +38,8 @@ static void __dma_tx_complete(void *para |
| |
| if (!uart_circ_empty(xmit) && !uart_tx_stopped(&p->port)) |
| serial8250_tx_dma(p); |
| + |
| + spin_unlock_irqrestore(&p->port.lock, flags); |
| } |
| |
| static void __dma_rx_complete(void *param) |
