On Mon, Nov 21, 2022 at 02:49:25PM +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(-)
Applied to 5.4.y only. Fails to apply to 4.9.y, 4.14.y, or 4.19.y :(
