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

Change-Id: I3ad39b420ce79a8602a7eca1daac1f56b30bad5c
Signed-off-by: Benoit Goby <benoit@android.com>

1 files changed, 24 insertions, 4 deletions

diff --git a/drivers/usb/gadget/android.c b/drivers/usb/gadget/android.c
index 2b76310..00a446b 100644
--- a/drivers/usb/gadget/android.c
+++ b/drivers/usb/gadget/android.c
@@ -100,6 +100,7 @@ struct android_dev {
 	struct device *dev;
 
 	bool enabled;
+	struct mutex mutex;
 	bool connected;
 	bool sw_connected;
 	struct work_struct work;
@@ -774,8 +775,13 @@ 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;
@@ -790,6 +796,13 @@ 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));
@@ -804,6 +817,8 @@ functions_store(struct device *pdev, struct device_attribute *attr,
 		}
 	}
 
+	mutex_unlock(&dev->mutex);
+
 	return size;
 }
 
@@ -821,6 +836,8 @@ static ssize_t enable_store(struct device *pdev, struct device_attribute *attr,
 	struct usb_composite_dev *cdev = dev->cdev;
 	int enabled = 0;
 
+	mutex_lock(&dev->mutex);
+
 	sscanf(buff, "%d", &enabled);
 	if (enabled && !dev->enabled) {
 		cdev->next_string_id = 0;
@@ -845,6 +862,8 @@ 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;
 }
 
@@ -878,9 +897,9 @@ field ## _show(struct device *dev, struct device_attribute *attr,	\
 }									\
 static ssize_t								\
 field ## _store(struct device *dev, struct device_attribute *attr,	\
-		const char *buf, size_t size)		       		\
+		const char *buf, size_t size)				\
 {									\
-	int value;					       		\
+	int value;							\
 	if (sscanf(buf, format_string, &value) == 1) {			\
 		device_desc.field = value;				\
 		return size;						\
@@ -898,10 +917,10 @@ field ## _show(struct device *dev, struct device_attribute *attr,	\
 }									\
 static ssize_t								\
 field ## _store(struct device *dev, struct device_attribute *attr,	\
-		const char *buf, size_t size)		       		\
+		const char *buf, size_t size)				\
 {									\
 	if (size >= sizeof(buffer)) return -EINVAL;			\
-	if (sscanf(buf, "%s", buffer) == 1) {			       	\
+	if (sscanf(buf, "%s", buffer) == 1) {				\
 		return size;						\
 	}								\
 	return -1;							\
@@ -1136,6 +1155,7 @@ 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) {