usb: gadget: android: Don't allow changing the functions list if enabled

Change-Id: I3ad39b420ce79a8602a7eca1daac1f56b30bad5c
Signed-off-by: Benoit Goby <[email protected]>

Conflicts:

	drivers/usb/gadget/android.c

drivers/usb/gadget/android.c

@@ -109,7 +109,8 @@ struct android_dev {
 	struct device *dev;
 
 	bool enabled;
-        int disable_depth;
+	struct mutex mutex;
+	int disable_depth;
 	bool connected;
 	bool sw_connected;
 	struct work_struct work;
@@ -886,8 +887,11 @@ functions_show(struct device *pdev, struct device_attribute *attr, char *buf)
 	struct android_usb_function *f;
 	char *buff = buf;
 
+	mutex_lock(&dev->mutex);
+
 	list_for_each_entry(f, &dev->enabled_functions, enabled_list)
 		buff += sprintf(buff, "%s,", f->name);
+	mutex_unlock(&dev->mutex);
 	if (buff != buf)
 		*(buff-1) = '\n';
 	return buff - buf;
@@ -902,6 +906,13 @@ functions_store(struct device *pdev, struct device_attribute *attr,
 	char buf[256], *b;
 	int err;
 
+	mutex_lock(&dev->mutex);
+
+	if (dev->enabled) {
+		mutex_unlock(&dev->mutex);
+		return -EBUSY;
+	}
+
 	INIT_LIST_HEAD(&dev->enabled_functions);
 
 	strncpy(buf, buff, sizeof(buf));
@@ -915,6 +926,7 @@ functions_store(struct device *pdev, struct device_attribute *attr,
 				pr_err("android_usb: Cannot enable '%s'", name);
 		}
 	}
+	mutex_unlock(&dev->mutex);
 
 	return size;
 }
@@ -934,6 +946,7 @@ static ssize_t enable_store(struct device *pdev, struct device_attribute *attr,
 	struct android_usb_function *f;
 	int enabled = 0;
 
+	mutex_lock(&dev->mutex);
 	sscanf(buff, "%d", &enabled);
 	if (enabled && !dev->enabled) {
 		cdev->next_string_id = 0;
@@ -963,6 +976,7 @@ static ssize_t enable_store(struct device *pdev, struct device_attribute *attr,
 		pr_err("android_usb: already %s\n",
 				dev->enabled ? "enabled" : "disabled");
 	}
+	mutex_unlock(&dev->mutex);
 	return size;
 }
 
@@ -1254,6 +1268,7 @@ static int __init init(void)
 	dev->functions = supported_functions;
 	INIT_LIST_HEAD(&dev->enabled_functions);
 	INIT_WORK(&dev->work, android_work);
+	mutex_init(&dev->mutex);
 
 	err = android_create_device(dev);
 	if (err) {