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 5.4-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-5.4 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
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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
@@ -1824,10 +1824,9 @@ 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);
- /* fall-through */
- 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-5.4/serial-8250-flush-dma-rx-on-rlsi.patch
queue-5.4/serial-8250_lpss-configure-dma-also-w-o-dma-filter.patch
queue-5.4/serial-8250-fall-back-to-non-dma-rx-if-iir_rdi-occurs.patch
queue-5.4/serial-8250_omap-remove-wait-loop-from-errata-i202-w.patch
