This is a note to let you know that I've just added the patch titled
serial: sh-sci: Fix race condition causing garbage during shutdown
to the 4.4-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-sh-sci-fix-race-condition-causing-garbage-during-shutdown.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Apr 10 10:31:53 CEST 2018
From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Date: Tue, 25 Apr 2017 20:15:35 +0200
Subject: serial: sh-sci: Fix race condition causing garbage during shutdown
From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
[ Upstream commit 1cf4a7efdc71cab84c42cfea7200608711ea954f ]
If DMA is enabled and used, a burst of old data may be seen on the
serial console during "poweroff" or "reboot". uart_flush_buffer()
clears the circular buffer, but sci_port.tx_dma_len is not reset.
This leads to a circular buffer overflow, dumping (UART_XMIT_SIZE -
sci_port.tx_dma_len) bytes.
To fix this, add a .flush_buffer() callback that resets
sci_port.tx_dma_len.
Inspired by commit 31ca2c63fdc0aee7 ("tty/serial: atmel: fix race
condition (TX+DMA)").
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/sh-sci.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1457,7 +1457,16 @@ static void sci_free_dma(struct uart_por
if (s->chan_rx)
sci_rx_dma_release(s, false);
}
-#else
+
+static void sci_flush_buffer(struct uart_port *port)
+{
+ /*
+ * In uart_flush_buffer(), the xmit circular buffer has just been
+ * cleared, so we have to reset tx_dma_len accordingly.
+ */
+ to_sci_port(port)->tx_dma_len = 0;
+}
+#else /* !CONFIG_SERIAL_SH_SCI_DMA */
static inline void sci_request_dma(struct uart_port *port)
{
}
@@ -1465,7 +1474,9 @@ static inline void sci_request_dma(struc
static inline void sci_free_dma(struct uart_port *port)
{
}
-#endif
+
+#define sci_flush_buffer NULL
+#endif /* !CONFIG_SERIAL_SH_SCI_DMA */
static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
{
@@ -2205,6 +2216,7 @@ static struct uart_ops sci_uart_ops = {
.break_ctl = sci_break_ctl,
.startup = sci_startup,
.shutdown = sci_shutdown,
+ .flush_buffer = sci_flush_buffer,
.set_termios = sci_set_termios,
.pm = sci_pm,
.type = sci_type,
Patches currently in stable-queue which might be from geert+renesas@xxxxxxxxx are
queue-4.4/serial-sh-sci-fix-race-condition-causing-garbage-during-shutdown.patch
queue-4.4/sh_eth-use-platform-device-for-printing-before-register_netdev.patch