__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@xxxxxxxxx>
---
v2: extend lock to protect xmit tail (cf doc)
and tx_running. tx_running and tail have to
be updated atomically.
update commit message.
drivers/tty/serial/8250/8250_dma.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index 7046769..ab9096d 100644
--- 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 *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)
--
1.8.3.2
--
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