trace: use prepare credential guard

Use the prepare credential guard for allocating a new set of
credentials.

Link: https://patch.msgid.link/20251103-work-creds-guards-prepare_creds-v1-11-b447b82f2c9b@kernel.org
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: brauner

kernel/trace/trace_events_user.c

@@ -1451,10 +1451,8 @@ static int user_event_set_call_visible(struct user_event *user, bool visible)
 {
 	int ret;
 	const struct cred *old_cred;
-	struct cred *cred;
-
-	cred = prepare_creds();
 
+	CLASS(prepare_creds, cred)();
 	if (!cred)
 		return -ENOMEM;
 
@@ -1477,7 +1475,6 @@ static int user_event_set_call_visible(struct user_event *user, bool visible)
 		ret = trace_remove_event_call(&user->call);
 
 	revert_creds(old_cred);
-	put_cred(cred);
 
 	return ret;
 }