USB: gadget: f_fs: use usb_string_ids_n()

Use usb_string_ids_n() function to simplify string ids
registeration.
Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/f_fs.c

@@ -1375,7 +1375,8 @@ static void ffs_data_reset(struct ffs_data *ffs)
 
 static int functionfs_bind(struct ffs_data *ffs, struct usb_composite_dev *cdev)
 {
-	unsigned i, count;
+	struct usb_gadget_strings **lang;
+	int first_id;
 
 	ENTER();
 
@@ -1383,7 +1384,9 @@ static int functionfs_bind(struct ffs_data *ffs, struct usb_composite_dev *cdev)
 		 || test_and_set_bit(FFS_FL_BOUND, &ffs->flags)))
 		return -EBADFD;
 
-	ffs_data_get(ffs);
+	first_id = usb_string_ids_n(cdev, ffs->strings_count);
+	if (unlikely(first_id < 0))
+		return first_id;
 
 	ffs->ep0req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
 	if (unlikely(!ffs->ep0req))
@@ -1391,25 +1394,16 @@ static int functionfs_bind(struct ffs_data *ffs, struct usb_composite_dev *cdev)
 	ffs->ep0req->complete = ffs_ep0_complete;
 	ffs->ep0req->context = ffs;
 
-	/* Get strings identifiers */
-	for (count = ffs->strings_count, i = 0; i < count; ++i) {
-		struct usb_gadget_strings **lang;
-
-		int id = usb_string_id(cdev);
-		if (unlikely(id < 0)) {
-			usb_ep_free_request(cdev->gadget->ep0, ffs->ep0req);
-			ffs->ep0req = NULL;
-			return id;
-		}
-
 	lang = ffs->stringtabs;
-		do {
-			(*lang)->strings[i].id = id;
-			++lang;
-		} while (*lang);
+	for (lang = ffs->stringtabs; *lang; ++lang) {
+		struct usb_string *str = (*lang)->strings;
+		int id = first_id;
+		for (; str->s; ++id, ++str)
+			str->id = id;
 	}
 
 	ffs->gadget = cdev->gadget;
+	ffs_data_get(ffs);
 	return 0;
 }