[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>
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 36b1ae0..f5ce58d 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -828,7 +828,10 @@
if ((!file || !tty_hung_up_p(file)) &&
!(tty->flags & (1 << TTY_IO_ERROR))) {
result = port->mctrl;
+
+ spin_lock_irq(&port->lock);
result |= port->ops->get_mctrl(port);
+ spin_unlock_irq(&port->lock);
}
up(&state->sem);
@@ -1369,6 +1372,7 @@
DECLARE_WAITQUEUE(wait, current);
struct uart_info *info = state->info;
struct uart_port *port = state->port;
+ unsigned int mctrl;
info->blocked_open++;
state->count--;
@@ -1416,7 +1420,10 @@
* and wait for the carrier to indicate that the
* modem is ready for us.
*/
- if (port->ops->get_mctrl(port) & TIOCM_CAR)
+ spin_lock_irq(&port->lock);
+ mctrl = port->ops->get_mctrl(port);
+ spin_unlock_irq(&port->lock);
+ if (mctrl & TIOCM_CAR)
break;
up(&state->sem);
@@ -1618,7 +1625,9 @@
if(capable(CAP_SYS_ADMIN))
{
+ spin_lock_irq(&port->lock);
status = port->ops->get_mctrl(port);
+ spin_unlock_irq(&port->lock);
ret += sprintf(buf + ret, " tx:%d rx:%d",
port->icount.tx, port->icount.rx);