From 98f8b83d6a504615f52a095acf92a2bdad985ae0 Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter@hurleysoftware.com>
Date: Tue, 2 Sep 2014 17:39:17 -0400
Subject: [PATCH] serial: sunsab: Don't enable tx if tx stopped

The serial core may call the UART driver's start_tx() even if
tx is stopped; the UART driver must verify tx should be enabled
before transmitting.

Reported-by: Sam Ravnborg <sam@ravnborg.org>
cc: David S. Miller <davem@davemloft.net>
cc: <sparclinux@vger.kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/sunsab.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sunsab.c b/drivers/tty/serial/sunsab.c
index 0af75f8b98a4..b339fe4811cd 100644
--- a/drivers/tty/serial/sunsab.c
+++ b/drivers/tty/serial/sunsab.c
@@ -436,7 +436,7 @@ static void sunsab_start_tx(struct uart_port *port)
 	struct circ_buf *xmit = &up->port.state->xmit;
 	int i;
 
-	if (uart_circ_empty(xmit))
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 		return;
 
 	up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR);