UBI: cleanup usage of try_module_get

The use of try_module_get(THIS_MODULE) in ubi_get_device_info does not
offer real protection against unexpected driver unloads, since we could
be preempted before try_modules_get gets executed. It is the caller who
should manipulate the refcounts. Besides, ubi_get_device_info is an
exported symbol which guarantees protection when accessed through
symbol_get.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/kapi.c

@@ -37,12 +37,8 @@ int ubi_get_device_info(int ubi_num, struct ubi_device_info *di)
 {
 	const struct ubi_device *ubi;
 
-	if (!try_module_get(THIS_MODULE))
-		return -ENODEV;
-
 	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES ||
 	    !ubi_devices[ubi_num]) {
-		module_put(THIS_MODULE);
 		return -ENODEV;
 	}
 
@@ -52,7 +48,6 @@ int ubi_get_device_info(int ubi_num, struct ubi_device_info *di)
 	di->min_io_size = ubi->min_io_size;
 	di->ro_mode = ubi->ro_mode;
 	di->cdev = MKDEV(ubi->major, 0);
-	module_put(THIS_MODULE);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(ubi_get_device_info);