+/*
+ * Grabs an event device (along with underlying input device).
+ * This function is called with evdev->mutex taken.
+ */
+static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
+{
+ int error;
+
+ if (evdev->grab)
+ return -EBUSY;
+
+ error = input_grab_device(&evdev->handle);
+ if (error)
+ return error;
+
+ rcu_assign_pointer(evdev->grab, client);
+ synchronize_rcu();
+
+ return 0;
+}
+
+static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
+{
+ if (evdev->grab != client)
+ return -EINVAL;
+
+ rcu_assign_pointer(evdev->grab, NULL);
+ synchronize_rcu();
+ input_release_device(&evdev->handle);
+
+ return 0;
+}
+
+static void evdev_attach_client(struct evdev *evdev,
+ struct evdev_client *client)
+{
+ spin_lock(&evdev->client_lock);
+ list_add_tail_rcu(&client->node, &evdev->client_list);
+ spin_unlock(&evdev->client_lock);
+ synchronize_rcu();
+}
+
+static void evdev_detach_client(struct evdev *evdev,
+ struct evdev_client *client)
+{
+ spin_lock(&evdev->client_lock);
+ list_del_rcu(&client->node);
+ spin_unlock(&evdev->client_lock);
+ synchronize_rcu();
+}
+
+static int evdev_open_device(struct evdev *evdev)
+{
+ int retval;
+
+ retval = mutex_lock_interruptible(&evdev->mutex);
+ if (retval)
+ return retval;
+
+ if (!evdev->exist)
+ retval = -ENODEV;
+ else if (!evdev->open++) {
+ retval = input_open_device(&evdev->handle);
+ if (retval)
+ evdev->open--;
+ }
+
+ mutex_unlock(&evdev->mutex);
+ return retval;
+}
+
+static void evdev_close_device(struct evdev *evdev)
+{
+ mutex_lock(&evdev->mutex);
+
+ if (evdev->exist && !--evdev->open)
+ input_close_device(&evdev->handle);
+
+ mutex_unlock(&evdev->mutex);
+}
+
+/*
+ * Wake up users waiting for IO so they can disconnect from
+ * dead device.
+ */
+static void evdev_hangup(struct evdev *evdev)
+{
+ struct evdev_client *client;
+
+ spin_lock(&evdev->client_lock);
+ list_for_each_entry(client, &evdev->client_list, node)
+ kill_fasync(&client->fasync, SIGIO, POLL_HUP);
+ spin_unlock(&evdev->client_lock);
+
+ wake_up_interruptible(&evdev->wait);
+}
+