[18/40] atmel_serial: fix spinlock lockup in RS485 code

[Greg KH]

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Claudio Scordino <claudio@xxxxxxxxxxxxxxx>

commit dbf1115d3f8c7052788aa4e6e46abd27f3b3eeba upstream.

Patch to fix a spinlock lockup in the driver that sometimes happens when the
tasklet starts.

Signed-off-by: Claudio Scordino <claudio@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Bender <codehero@xxxxxxxxx>
Tested-by: Dave Bender <codehero@xxxxxxxxx>
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/tty/serial/atmel_serial.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -199,8 +199,9 @@ void atmel_config_rs485(struct uart_port
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	unsigned int mode;
+	unsigned long flags;
 
-	spin_lock(&port->lock);
+	spin_lock_irqsave(&port->lock, flags);
 
 	/* Disable interrupts */
 	UART_PUT_IDR(port, atmel_port->tx_done_mask);
@@ -231,7 +232,7 @@ void atmel_config_rs485(struct uart_port
 	/* Enable interrupts */
 	UART_PUT_IER(port, atmel_port->tx_done_mask);
 
-	spin_unlock(&port->lock);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 }
 


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