1 files changed, 47 insertions, 64 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 87802ea8bbc8..7d207d91a6a8 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -187,100 +187,92 @@ void usb_serial_put(struct usb_serial *serial)
  * Create the termios objects for this tty.  We use the default
  * USB serial settings but permit them to be overridden by
  * serial->type->init_termios.
+ *
+ * This is the first place a new tty gets used.  Hence this is where we
+ * acquire references to the usb_serial structure and the driver module,
+ * where we store a pointer to the port, and where we do an autoresume.
+ * All these actions are reversed in serial_do_free().
  */
 static int serial_install(struct tty_driver *driver, struct tty_struct *tty)
 {
         int idx = tty->index;
         struct usb_serial *serial;
-        int retval;
+        struct usb_serial_port *port;
+        int retval = -ENODEV;
+
+        serial = usb_serial_get_by_index(idx);
+        if (!serial)
+                return retval;
+
+        port = serial->port[idx - serial->minor];
+        if (!port)
+                goto error_no_port;
+        if (!try_module_get(serial->type->driver.owner))
+                goto error_module_get;
+
+        retval = usb_autopm_get_interface(serial->interface);
+        if (retval)
+                goto error_get_interface;
 
         /* If the termios setup has yet to be done */
         if (tty->driver->termios[idx] == NULL) {
                 /* perform the standard setup */
                 retval = tty_init_termios(tty);
                 if (retval)
-                        return retval;
+                        goto error_init_termios;
                 /* allow the driver to update it */
-                serial = usb_serial_get_by_index(tty->index);
-                if (serial) {
-                        if (serial->type->init_termios)
-                                serial->type->init_termios(tty);
-                        usb_serial_put(serial);
-                        mutex_unlock(&serial->disc_mutex);
-                }
+                if (serial->type->init_termios)
+                        serial->type->init_termios(tty);
         }
+        mutex_unlock(&serial->disc_mutex);
+
+        tty->driver_data = port;
+
         /* Final install (we use the default method) */
         tty_driver_kref_get(driver);
         tty->count++;
         driver->ttys[idx] = tty;
-        return 0;
+        return retval;
+
+ error_init_termios:
+        usb_autopm_put_interface(serial->interface);
+ error_get_interface:
+        module_put(serial->type->driver.owner);
+ error_module_get:
+ error_no_port:
+        usb_serial_put(serial);
+        mutex_unlock(&serial->disc_mutex);
+        return retval;
 }
 
 static int serial_open (struct tty_struct *tty, struct file *filp)
 {
         struct usb_serial *serial;
         struct usb_serial_port *port;
-        unsigned int portNumber;
         int retval = 0;
         int first = 0;
 
         dbg("%s", __func__);
 
-        /* get the serial object associated with this tty pointer */
-        serial = usb_serial_get_by_index(tty->index);
-        if (!serial) {
-                tty->driver_data = NULL;
-                return -ENODEV;
-        }
-
-        portNumber = tty->index - serial->minor;
-        port = serial->port[portNumber];
-        if (!port || serial->disconnected)
-                retval = -ENODEV;
-        /*
-         * Note: Our locking order requirement does not allow port->mutex
-         * to be acquired while serial->disc_mutex is held.
-         */
-        mutex_unlock(&serial->disc_mutex);
-        if (retval)
-                goto bailout_serial_put;
+        port = tty->driver_data;
+        serial = port->serial;
 
-        if (mutex_lock_interruptible(&port->mutex)) {
-                retval = -ERESTARTSYS;
-                goto bailout_serial_put;
-        }
+        if (mutex_lock_interruptible(&port->mutex))
+                return -ERESTARTSYS;
 
         ++port->port.count;
-
-        /* set up our port structure making the tty driver
-         * remember our port object, and us it */
-        tty->driver_data = port;
         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;
-                /* lock this module before we call it
-                 * this may fail, which means we must bail out,
-                 * safe because we are called with BKL held */
-                if (!try_module_get(serial->type->driver.owner)) {
-                        retval = -ENODEV;
-                        goto bailout_mutex_unlock;
-                }
-
                 mutex_lock(&serial->disc_mutex);
-                if (serial->disconnected)
-                        retval = -ENODEV;
-                else
-                        retval = usb_autopm_get_interface(serial->interface);
-                if (retval)
-                        goto bailout_module_put;
 
                 /* 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_interface_put;
+                        goto bailout_module_put;
                 mutex_unlock(&serial->disc_mutex);
                 set_bit(ASYNCB_INITIALIZED, &port->port.flags);
         }
@@ -297,18 +289,11 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
                 goto bailout_mutex_unlock;
         /* Undo the initial port actions */
         mutex_lock(&serial->disc_mutex);
-bailout_interface_put:
-        usb_autopm_put_interface(serial->interface);
 bailout_module_put:
         mutex_unlock(&serial->disc_mutex);
-        module_put(serial->type->driver.owner);
 bailout_mutex_unlock:
         port->port.count = 0;
-        tty->driver_data = NULL;
-        tty_port_tty_set(&port->port, NULL);
         mutex_unlock(&port->mutex);
-bailout_serial_put:
-        usb_serial_put(serial);
         return retval;
 }
 
@@ -355,9 +340,6 @@ static void serial_close(struct tty_struct *tty, struct file *filp)
 {
         struct usb_serial_port *port = tty->driver_data;
 
-        if (!port)
-                return;
-
         dbg("%s - port %d", __func__, port->number);
 
         if (tty_port_close_start(&port->port, tty, filp) == 0)
@@ -365,7 +347,6 @@ static void serial_close(struct tty_struct *tty, struct file *filp)
         serial_do_down(port);
         tty_port_close_end(&port->port, tty);
         tty_port_tty_set(&port->port, NULL);
-
 }
 
 /**
@@ -386,9 +367,11 @@ static void serial_do_free(struct tty_struct *tty)
         /* The console is magical.  Do not hang up the console hardware
          * or there will be tears.
          */
-        if (port == NULL || port->console)
+        if (port->console)
                 return;
 
+        tty->driver_data = NULL;
+
         serial = port->serial;
         owner = serial->type->driver.owner;