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serial: 8250: Fix thread unsafe __dma_tx_complete function

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__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 <[email protected]>
Reviewed-by: Heikki Krogerus <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
This commit is contained in:
Loic Poulain 2014-04-24 11:34:48 +02:00 • committed by Greg Kroah-Hartman
commit f8fd1b0350
1 changed files with 7 additions and 2 deletions
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9
drivers/tty/serial/8250/8250_dma.c
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@ -20,12 +20,15 @@ static void __dma_tx_complete(void *param)
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 *param)
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)