The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
Possible dependencies:
1980860e0c82 ("serial: 8250: Flush DMA Rx on RLSI")
a931237cbea2 ("serial: 8250: Fall back to non-DMA Rx if IIR_RDI occurs")
df561f6688fe ("treewide: Use fallthrough pseudo-keyword")
37711e5e2325 ("Merge tag 'nfs-for-5.9-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>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: [PATCH] serial: 8250: Flush DMA Rx on RLSI
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
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>
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 92dd18716169..388172289627 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1901,10 +1901,9 @@ 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);
- fallthrough;
- case UART_IIR_RLSI:
return true;
}
return up->dma->rx_dma(up);
