On Mon, Jan 30, 2023 at 01:48:40PM +0200, Ilpo Järvinen wrote:
__dma_rx_complete() is called from two places:
- Through the DMA completion callback dma_rx_complete()
- From serial8250_rx_dma_flush() after IIR_RLSI or IIR_RX_TIMEOUT
The former does not hold port's lock during __dma_rx_complete() which allows these two to race and potentially insert the same data twice.
Extend port's lock coverage in dma_rx_complete() to prevent the race and check if the DMA Rx is still pending completion before calling into __dma_rx_complete().
Reported-by: Gilles BULOZ gilles.buloz@kontron.com Tested-by: Gilles BULOZ gilles.buloz@kontron.com Fixes: 9ee4b83e51f7 ("serial: 8250: Add support for dmaengine") Cc: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com
FWIW:
Acked-by: Heikki Krogerus heikki.krogerus@linux.intel.com
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 37d6af2ec427..5594883a96f8 100644 --- a/drivers/tty/serial/8250/8250_dma.c +++ b/drivers/tty/serial/8250/8250_dma.c @@ -62,9 +62,14 @@ static void dma_rx_complete(void *param) struct uart_8250_dma *dma = p->dma; unsigned long flags;
- __dma_rx_complete(p);
- spin_lock_irqsave(&p->port.lock, flags);
- if (dma->rx_running)
__dma_rx_complete(p);- /*
* Cannot be combined with the previous check because __dma_rx_complete()* changes dma->rx_running.*/-- 2.30.2