From 32a7f0645111a99df3f68e59e362fe97de093736 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Tue, 8 Nov 2022 14:19:52 +0200 Subject: [PATCH] serial: 8250: Flush DMA Rx on RLSI MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: Signed-off-by: Ilpo Järvinen Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20221108121952.5497-5-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- 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 8b76d5666f59..907130244e1f 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1824,10 +1824,9 @@ static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir) if (!up->dma->rx_running) break; fallthrough; + 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);