On Tue, Nov 22, 2022 at 03:14:10PM +0200, Ilpo Järvinen wrote:
> commit 1980860e0c8299316cddaf0992dd9e1258ec9d88 upstream.
>
> Returning true from handle_rx_dma() without flushing DMA first creates
> a data ordering hazard. If DMA Rx has handled any character at the
> point when RLSI occurs, the non-DMA path handles any pending characters
> jumping them ahead of those characters that are pending under DMA.
>
> Fixes: 75df022b5f89 ("serial: 8250_dma: Fix RX handling")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/20221108121952.5497-5-ilpo.jarvinen@xxxxxxxxxxxxxxx
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/tty/serial/8250/8250_port.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index cab3a74281ef..8aee43fe488a 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -1802,10 +1802,9 @@ static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)
> if (!up->dma->rx_running)
> break;
> /* fall-through */
> + case UART_IIR_RLSI:
> case UART_IIR_RX_TIMEOUT:
> serial8250_rx_dma_flush(up);
> - /* fall-through */
> - case UART_IIR_RLSI:
> return true;
> }
> return up->dma->rx_dma(up);
> --
> 2.30.2
Now queued up, thanks.
greg k-h
