tty_port: add "tty_port_open" helper

For the moment this just moves the USB logic over and fixes the 'what if
we open and hangup at the same time' race noticed by Oliver Neukum.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 20 insertions, 29 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index bd3fa7ff15b1..b0649d92251f 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -247,41 +247,31 @@ static int serial_install(struct tty_driver *driver, struct tty_struct *tty)
         return retval;
 }
 
-static int serial_open(struct tty_struct *tty, struct file *filp)
+static int serial_activate(struct tty_port *tport, struct tty_struct *tty)
 {
-        struct usb_serial_port *port = tty->driver_data;
+        struct usb_serial_port *port =
+                container_of(tport, struct usb_serial_port, port);
         struct usb_serial *serial = port->serial;
         int retval;
 
-        dbg("%s - port %d", __func__, port->number);
-
-        spin_lock_irq(&port->port.lock);
-        if (!tty_hung_up_p(filp))
-                ++port->port.count;
-        spin_unlock_irq(&port->port.lock);
-        tty_port_tty_set(&port->port, tty);
+        if (mutex_lock_interruptible(&port->mutex))
+                return -ERESTARTSYS;
+        mutex_lock(&serial->disc_mutex);
+        if (serial->disconnected)
+                retval = -ENODEV;
+        else
+                retval = port->serial->type->open(tty, port);
+        mutex_unlock(&serial->disc_mutex);
+        mutex_unlock(&port->mutex);
+        return retval;
+}
 
-        /* Do the device-specific open only if the hardware isn't
-         * already initialized.
-         */
-        if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
-                if (mutex_lock_interruptible(&port->mutex))
-                        return -ERESTARTSYS;
-                mutex_lock(&serial->disc_mutex);
-                if (serial->disconnected)
-                        retval = -ENODEV;
-                else
-                        retval = port->serial->type->open(tty, port);
-                mutex_unlock(&serial->disc_mutex);
-                mutex_unlock(&port->mutex);
-                if (retval)
-                        return retval;
-                set_bit(ASYNCB_INITIALIZED, &port->port.flags);
-        }
+static int serial_open(struct tty_struct *tty, struct file *filp)
+{
+        struct usb_serial_port *port = tty->driver_data;
 
-        /* Now do the correct tty layer semantics */
-        retval = tty_port_block_til_ready(&port->port, tty, filp);
-        return retval;
+        dbg("%s - port %d", __func__, port->number);
+        return tty_port_open(&port->port, tty, filp);
 }
 
 /**
@@ -725,6 +715,7 @@ static void serial_dtr_rts(struct tty_port *port, int on)
 static const struct tty_port_operations serial_port_ops = {
         .carrier_raised = serial_carrier_raised,
         .dtr_rts = serial_dtr_rts,
+        .activate = serial_activate,
 };
 
 int usb_serial_probe(struct usb_interface *interface,