tty: usb-serial krefs

Use kref in the USB serial drivers so that we don't free tty structures
from under the URB receive handlers as has historically been the case if
you were unlucky. This also gives us a framework for general tty drivers to
use tty_port objects and refcount.

Contains two err->dev_err changes merged together to fix clashes in the
-next tree.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 9 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 4f7f9e3ae0a4..e7d4246027b2 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -214,7 +214,7 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
 	/* set up our port structure making the tty driver
 	 * remember our port object, and us it */
 	tty->driver_data = port;
-	port->port.tty = tty;
+	tty_port_tty_set(&port->port, tty);
 
 	if (port->port.count == 1) {
 
@@ -246,7 +246,7 @@ bailout_module_put:
 bailout_mutex_unlock:
 	port->port.count = 0;
 	tty->driver_data = NULL;
-	port->port.tty = NULL;
+	tty_port_tty_set(&port->port, NULL);
 	mutex_unlock(&port->mutex);
 bailout_kref_put:
 	usb_serial_put(serial);
@@ -276,10 +276,11 @@ static void serial_close(struct tty_struct *tty, struct file *filp)
 		port->serial->type->close(tty, port, filp);
 
 	if (port->port.count == (port->console? 1 : 0)) {
-		if (port->port.tty) {
-			if (port->port.tty->driver_data)
-				port->port.tty->driver_data = NULL;
-			port->port.tty = NULL;
+		struct tty_struct *tty = tty_port_tty_get(&port->port);
+		if (tty) {
+			if (tty->driver_data)
+				tty->driver_data = NULL;
+			tty_port_tty_set(&port->port, NULL);
 		}
 	}
 
@@ -508,11 +509,12 @@ static void usb_serial_port_work(struct work_struct *work)
 	if (!port)
 		return;
 
-	tty = port->port.tty;
+	tty = tty_port_tty_get(&port->port);
 	if (!tty)
 		return;
 
 	tty_wakeup(tty);
+	tty_kref_put(tty);
 }
 
 static void port_release(struct device *dev)
@@ -819,6 +821,7 @@ int usb_serial_probe(struct usb_interface *interface,
 		port = kzalloc(sizeof(struct usb_serial_port), GFP_KERNEL);
 		if (!port)
 			goto probe_error;
+		tty_port_init(&port->port);
 		port->serial = serial;
 		spin_lock_init(&port->lock);
 		mutex_init(&port->mutex);
@@ -1040,8 +1043,11 @@ void usb_serial_disconnect(struct usb_interface *interface)
 	for (i = 0; i < serial->num_ports; ++i) {
 		port = serial->port[i];
 		if (port) {
-			if (port->port.tty)
-				tty_hangup(port->port.tty);
+			struct tty_struct *tty = tty_port_tty_get(&port->port);
+			if (tty) {
+				tty_hangup(tty);
+				tty_kref_put(tty);
+			}
 			kill_traffic(port);
 		}
 	}