This is a note to let you know that I've just added the patch titled
tty/serial: atmel: fix race condition (TX+DMA)
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 31ca2c63fdc0aee725cbd4f207c1256f5deaabde Mon Sep 17 00:00:00 2001
From: Richard Genoud <richard.genoud@xxxxxxxxx>
Date: Mon, 20 Mar 2017 11:52:41 +0100
Subject: tty/serial: atmel: fix race condition (TX+DMA)
If uart_flush_buffer() is called between atmel_tx_dma() and
atmel_complete_tx_dma(), the circular buffer has been cleared, but not
atmel_port->tx_len.
That leads to a circular buffer overflow (dumping (UART_XMIT_SIZE -
atmel_port->tx_len) bytes).
Tested-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
Signed-off-by: Richard Genoud <richard.genoud@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx> # 3.12+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/atmel_serial.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index dcebb28ffbc4..5f644515ed33 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1951,6 +1951,11 @@ static void atmel_flush_buffer(struct uart_port *port)
atmel_uart_writel(port, ATMEL_PDC_TCR, 0);
atmel_port->pdc_tx.ofs = 0;
}
+ /*
+ * in uart_flush_buffer(), the xmit circular buffer has just
+ * been cleared, so we have to reset tx_len accordingly.
+ */
+ atmel_port->tx_len = 0;
}
/*
--
2.12.1