[PATCH] Serial: Adjust serial locking

This patch changes the way serial ports are locked when getting modem
status.  This change is necessary because we will need to atomically
read the modem status and take action depending on the CTS status.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 1 insertions, 6 deletions

diff --git a/drivers/serial/sunsab.c b/drivers/serial/sunsab.c
index 10e2990a40d4..8d198880756a 100644
--- a/drivers/serial/sunsab.c
+++ b/drivers/serial/sunsab.c
@@ -426,18 +426,15 @@ static void sunsab_set_mctrl(struct uart_port *port, unsigned int mctrl)
 		sunsab_tx_idle(up);
 }
 
-/* port->lock is not held.  */
+/* port->lock is held by caller and interrupts are disabled.  */
 static unsigned int sunsab_get_mctrl(struct uart_port *port)
 {
 	struct uart_sunsab_port *up = (struct uart_sunsab_port *) port;
-	unsigned long flags;
 	unsigned char val;
 	unsigned int result;
 
 	result = 0;
 
-	spin_lock_irqsave(&up->port.lock, flags);
-
 	val = readb(&up->regs->r.pvr);
 	result |= (val & up->pvr_dsr_bit) ? 0 : TIOCM_DSR;
 
@@ -447,8 +444,6 @@ static unsigned int sunsab_get_mctrl(struct uart_port *port)
 	val = readb(&up->regs->r.star);
 	result |= (val & SAB82532_STAR_CTS) ? TIOCM_CTS : 0;
 
-	spin_unlock_irqrestore(&up->port.lock, flags);
-
 	return result;
 }