atmel_serial: fix spinlock lockup in RS485 code

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@evidence.eu.com>
Signed-off-by: Dave Bender <codehero@gmail.com>
Tested-by: Dave Bender <codehero@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index af9b7814965..b989495c763 100644
--- 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 *port, struct serial_rs485 *rs485conf)
 {
         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 *port, struct serial_rs485 *rs485conf)
         /* Enable interrupts */
         UART_PUT_IER(port, atmel_port->tx_done_mask);
 
-        spin_unlock(&port->lock);
+        spin_unlock_irqrestore(&port->lock, flags);
 
 }