On Fri, 23 Mar 2018 19:30:34 -0700
Alexei Starovoitov [off-list ref] wrote:

+static void *for_each_tracepoint_range(struct tracepoint * const *begin,
+				       struct tracepoint * const *end,
+				       void *(*fct)(struct tracepoint *tp, void *priv),
+				       void *priv)
 {
 	struct tracepoint * const *iter;
+	void *ret;
 
 	if (!begin)
-		return;
-	for (iter = begin; iter < end; iter++)
-		fct(*iter, priv);
+		return NULL;
+	for (iter = begin; iter < end; iter++) {
+		ret = fct(*iter, priv);
+		if (ret)
+			return ret;

So you just stopped the loop here. You have an inconsistent state. What
about the functions that were called before. How do you undo them? Or
what about the rest that haven't been touched. This function gives no
feedback to the caller.

-- Steve

+	}
+	return NULL;
 }