USB: stop io performed by mos7720 upon close()

This fixes a problem where the mos7720 driver will make io to a device from
which it has been logically disconnected. It does so by introducing a flag by
which the generic usb serial code can signal the subdrivers their
disconnection and appropriate locking.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 34 insertions, 29 deletions

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 725991fadc26..40f3a0188807 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -564,22 +564,25 @@ static void mos7720_close(struct usb_serial_port *port, struct file *filp)
         }
 
         /* While closing port, shutdown all bulk read, write  *
-         * and interrupt read if they exists                  */
-        if (serial->dev) {
-                dbg("Shutdown bulk write");
-                usb_kill_urb(port->write_urb);
-                dbg("Shutdown bulk read");
-                usb_kill_urb(port->read_urb);
+         * and interrupt read if they exists, otherwise nop   */
+        dbg("Shutdown bulk write");
+        usb_kill_urb(port->write_urb);
+        dbg("Shutdown bulk read");
+        usb_kill_urb(port->read_urb);
+
+        mutex_lock(&serial->disc_mutex);
+        /* these commands must not be issued if the device has
+         * been disconnected */
+        if (!serial->disconnected) {
+                data = 0x00;
+                send_mos_cmd(serial, MOS_WRITE, port->number - port->serial->minor,
+                             0x04, &data);
+
+                data = 0x00;
+                send_mos_cmd(serial, MOS_WRITE, port->number - port->serial->minor,
+                             0x01, &data);
         }
-
-        data = 0x00;
-        send_mos_cmd(serial, MOS_WRITE, port->number - port->serial->minor,
-                     0x04, &data);
-
-        data = 0x00;
-        send_mos_cmd(serial, MOS_WRITE, port->number - port->serial->minor,
-                     0x01, &data);
-
+        mutex_unlock(&serial->disc_mutex);
         mos7720_port->open = 0;
 
         dbg("Leaving %s", __FUNCTION__);
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 28315b05c9cc..3ce98e8d7bce 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -634,6 +634,7 @@ static struct usb_serial * create_serial (struct usb_device *dev,
         serial->type = driver;
         serial->interface = interface;
         kref_init(&serial->kref);
+        mutex_init(&serial->disc_mutex);
 
         return serial;
 }
@@ -1089,20 +1090,22 @@ void usb_serial_disconnect(struct usb_interface *interface)
         usb_serial_console_disconnect(serial);
         dbg ("%s", __FUNCTION__);
 
+        mutex_lock(&serial->disc_mutex);
         usb_set_intfdata (interface, NULL);
-        if (serial) {
-                for (i = 0; i < serial->num_ports; ++i) {
-                        port = serial->port[i];
-                        if (port) {
-                                if (port->tty)
-                                        tty_hangup(port->tty);
-                                kill_traffic(port);
-                        }
+        /* must set a flag, to signal subdrivers */
+        serial->disconnected = 1;
+        for (i = 0; i < serial->num_ports; ++i) {
+                port = serial->port[i];
+                if (port) {
+                        if (port->tty)
+                                tty_hangup(port->tty);
+                        kill_traffic(port);
                 }
-                /* let the last holder of this object 
-                 * cause it to be cleaned up */
-                usb_serial_put(serial);
         }
+        /* let the last holder of this object
+         * cause it to be cleaned up */
+        mutex_unlock(&serial->disc_mutex);
+        usb_serial_put(serial);
         dev_info(dev, "device disconnected\n");
 }
 
@@ -1112,9 +1115,6 @@ int usb_serial_suspend(struct usb_interface *intf, pm_message_t message)
         struct usb_serial_port *port;
         int i, r = 0;
 
-        if (!serial) /* device has been disconnected */
-                return 0;
-
         for (i = 0; i < serial->num_ports; ++i) {
                 port = serial->port[i];
                 if (port)
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index ef1e430f7bfa..63b29b5332e6 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -129,6 +129,7 @@ struct usb_serial {
         struct usb_device *             dev;
         struct usb_serial_driver *      type;
         struct usb_interface *          interface;
+        unsigned char                   disconnected;
         unsigned char                   minor;
         unsigned char                   num_ports;
         unsigned char                   num_port_pointers;
@@ -138,6 +139,7 @@ struct usb_serial {
         char                            num_bulk_out;
         struct usb_serial_port *        port[MAX_NUM_PORTS];
         struct kref                     kref;
+        struct mutex                    disc_mutex;
         void *                          private;
 };
 #define to_usb_serial(d) container_of(d, struct usb_serial, kref)