rv: Fix missing unlock on double nested monitors return path

RV doesn't support nested monitors having children monitors themselves
and exits with the EINVAL code. However, it returns without unlocking
the rv_interface_lock.

Unlock the lock before returning from the initialisation function.

Cc: Masami Hiramatsu <[email protected]>
Link: https://lore.kernel.org/[email protected]
Fixes: cb85c66 ("rv: Add option for nested monitors and include sched")
Reported-by: kernel test robot <[email protected]>
Reported-by: Julia Lawall <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]
Signed-off-by: Gabriele Monaco <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: glemco

kernel/trace/rv/rv.c

@@ -809,7 +809,8 @@ int rv_register_monitor(struct rv_monitor *monitor, struct rv_monitor *parent)
 	if (p && rv_is_nested_monitor(p)) {
 		pr_info("Parent monitor %s is already nested, cannot nest further\n",
 			parent->name);
-		return -EINVAL;
+		retval = -EINVAL;
+		goto out_unlock;
 	}
 
 	r = kzalloc(sizeof(struct rv_monitor_def), GFP_KERNEL);