usb-serial: straighten out serial_open

This patch (as1291) removes a bunch of code from serial_open(), things
that were rendered unnecessary by earlier patches.  A missing spinlock
is added to protect port->port.count, which needs to be incremented
even if the open fails but not if the tty has gotten a hangup.  The
test for whether the hardware has been initialized, based on the use
count, is replaced by a more transparent test of the
ASYNCB_INITIALIZED bit in the port flags.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 9a32580..9d7ca48 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -245,55 +245,40 @@ 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_open(struct tty_struct *tty, struct file *filp)
 {
-       struct usb_serial *serial;
-       struct usb_serial_port *port;
-       int retval = 0;
-       int first = 0;
-
-       port = tty->driver_data;
-       serial = port->serial;
+       struct usb_serial_port *port = tty->driver_data;
+       struct usb_serial *serial = port->serial;
+       int retval;
 
        dbg("%s - port %d", __func__, port->number);
 
-       if (mutex_lock_interruptible(&port->mutex))
-               return -ERESTARTSYS;
-
-       ++port->port.count;
+       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 the console is attached, the device is already open */
-       if (port->port.count == 1 && !port->console) {
-               first = 1;
+       /* 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);
-
-               /* only call the device specific open if this
-                * is the first time the port is opened */
-               retval = serial->type->open(tty, port);
-               if (retval)
-                       goto bailout_module_put;
+               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);
        }
-       mutex_unlock(&port->mutex);
+
        /* Now do the correct tty layer semantics */
        retval = tty_port_block_til_ready(&port->port, tty, filp);
-       if (retval == 0) {
-               if (!first)
-                       usb_serial_put(serial);
-               return 0;
-       }
-       mutex_lock(&port->mutex);
-       if (first == 0)
-               goto bailout_mutex_unlock;
-       /* Undo the initial port actions */
-       mutex_lock(&serial->disc_mutex);
-bailout_module_put:
-       mutex_unlock(&serial->disc_mutex);
-bailout_mutex_unlock:
-       port->port.count = 0;
-       mutex_unlock(&port->mutex);
        return retval;
 }