This is a note to let you know that I've just added the patch titled serial: 8250: Flush DMA Rx on RLSI to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: serial-8250-flush-dma-rx-on-rlsi.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 1980860e0c8299316cddaf0992dd9e1258ec9d88 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@xxxxxxxxxxxxxxx> Date: Tue, 8 Nov 2022 14:19:52 +0200 Subject: serial: 8250: Flush DMA Rx on RLSI MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx> 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(-) --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1873,10 +1873,9 @@ static bool handle_rx_dma(struct uart_82 if (!up->dma->rx_running) break; fallthrough; + case UART_IIR_RLSI: case UART_IIR_RX_TIMEOUT: serial8250_rx_dma_flush(up); - fallthrough; - case UART_IIR_RLSI: return true; } return up->dma->rx_dma(up); Patches currently in stable-queue which might be from ilpo.jarvinen@xxxxxxxxxxxxxxx are queue-5.10/serial-8250-remove-serial_rs485-sanitization-from-em.patch queue-5.10/serial-8250-flush-dma-rx-on-rlsi.patch queue-5.10/serial-8250_lpss-configure-dma-also-w-o-dma-filter.patch queue-5.10/serial-8250-fall-back-to-non-dma-rx-if-iir_rdi-occurs.patch queue-5.10/serial-8250_omap-remove-wait-loop-from-errata-i202-w.patch