[PATCH] USB console: fix disconnection issues

Prevent sending further output to a USB-serial console after the dongle is
disconnected, take care not to leak kref.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 29 insertions, 7 deletions

diff --git a/drivers/usb/serial/console.c b/drivers/usb/serial/console.c
index fc4a0f731d91..f3404e10afb4 100644
--- a/drivers/usb/serial/console.c
+++ b/drivers/usb/serial/console.c
@@ -202,7 +202,7 @@ static void usb_console_write(struct console *co, const char *buf, unsigned coun
         struct usb_serial *serial;
         int retval = -ENODEV;
 
-        if (!port)
+        if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
                 return;
         serial = port->serial;
 
@@ -255,6 +255,14 @@ static struct console usbcons = {
         .index =        -1,
 };
 
+void usb_serial_console_disconnect(struct usb_serial *serial)
+{
+        if (serial && serial->port && serial->port[0] && serial->port[0] == usbcons_info.port) {
+                usb_serial_console_exit();
+                usb_serial_put(serial);
+        }
+}
+
 void usb_serial_console_init (int serial_debug, int minor)
 {
         debug = serial_debug;
@@ -280,6 +288,11 @@ void usb_serial_console_init (int serial_debug, int minor)
 
 void usb_serial_console_exit (void)
 {
-        unregister_console(&usbcons);
+        if (usbcons_info.port) {
+                unregister_console(&usbcons);
+                if (usbcons_info.port->open_count)
+                        usbcons_info.port->open_count--;
+                usbcons_info.port = NULL;
+        }
 }
 
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index de9111d97a58..92200f05b531 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -168,6 +168,11 @@ static void destroy_serial(struct kref *kref)
         kfree (serial);
 }
 
+void usb_serial_put(struct usb_serial *serial)
+{
+        kref_put(&serial->kref, destroy_serial);
+}
+
 /*****************************************************************************
  * Driver tty interface functions
  *****************************************************************************/
@@ -232,7 +237,7 @@ bailout_mutex_unlock:
         port->open_count = 0;
         mutex_unlock(&port->mutex);
 bailout_kref_put:
-        kref_put(&serial->kref, destroy_serial);
+        usb_serial_put(serial);
         return retval;
 }
 
@@ -268,7 +273,7 @@ static void serial_close(struct tty_struct *tty, struct file * filp)
         }
 
         mutex_unlock(&port->mutex);
-        kref_put(&port->serial->kref, destroy_serial);
+        usb_serial_put(port->serial);
 }
 
 static int serial_write (struct tty_struct * tty, const unsigned char *buf, int count)
@@ -276,7 +281,7 @@ static int serial_write (struct tty_struct * tty, const unsigned char *buf, int
         struct usb_serial_port *port = tty->driver_data;
         int retval = -EINVAL;
 
-        if (!port)
+        if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
                 goto exit;
 
         dbg("%s - port %d, %d byte(s)", __FUNCTION__, port->number, count);
@@ -473,7 +478,7 @@ static int serial_read_proc (char *page, char **start, off_t off, int count, int
                         begin += length;
                         length = 0;
                 }
-                kref_put(&serial->kref, destroy_serial);
+                usb_serial_put(serial);
         }
         *eof = 1;
 done:
@@ -985,6 +990,7 @@ void usb_serial_disconnect(struct usb_interface *interface)
         struct device *dev = &interface->dev;
         struct usb_serial_port *port;
 
+        usb_serial_console_disconnect(serial);
         dbg ("%s", __FUNCTION__);
 
         usb_set_intfdata (interface, NULL);
@@ -996,7 +1002,7 @@ void usb_serial_disconnect(struct usb_interface *interface)
                 }
                 /* let the last holder of this object 
                  * cause it to be cleaned up */
-                kref_put(&serial->kref, destroy_serial);
+                usb_serial_put(serial);
         }
         dev_info(dev, "device disconnected\n");
 }
diff --git a/drivers/usb/serial/usb-serial.h b/drivers/usb/serial/usb-serial.h
index dc89d8710460..c07ece3fef1d 100644
--- a/drivers/usb/serial/usb-serial.h
+++ b/drivers/usb/serial/usb-serial.h
@@ -248,13 +248,16 @@ extern int ezusb_set_reset (struct usb_serial *serial, unsigned char reset_bit);
 #ifdef CONFIG_USB_SERIAL_CONSOLE
 extern void usb_serial_console_init (int debug, int minor);
 extern void usb_serial_console_exit (void);
+extern void usb_serial_console_disconnect(struct usb_serial *serial);
 #else
 static inline void usb_serial_console_init (int debug, int minor) { }
 static inline void usb_serial_console_exit (void) { }
+static inline void usb_serial_console_disconnect(struct usb_serial *serial) {}
 #endif
 
 /* Functions needed by other parts of the usbserial core */
 extern struct usb_serial *usb_serial_get_by_index (unsigned int minor);
+extern void usb_serial_put(struct usb_serial *serial);
 extern int usb_serial_generic_open (struct usb_serial_port *port, struct file *filp);
 extern int usb_serial_generic_write (struct usb_serial_port *port, const unsigned char *buf, int count);
 extern void usb_serial_generic_close (struct usb_serial_port *port, struct file *filp);