On Wed, Dec 17, 2025 at 08:48:14PM -0500, Steven Rostedt wrote:

On Mon, 15 Dec 2025 22:13:58 +0100
Jiri Olsa [off-list ref] wrote:

quoted

+/**
+ * hash_sub - substracts @b from @a and returns the result
+ * @a: struct ftrace_hash object
+ * @b: struct ftrace_hash object
+ *
+ * Returns struct ftrace_hash object on success, NULL on error.
+ */
+static struct ftrace_hash *hash_sub(struct ftrace_hash *a, struct ftrace_hash *b)
+{
+	struct ftrace_func_entry *entry, *del;
+	struct ftrace_hash *sub;
+	int size, i;
+
+	sub = alloc_and_copy_ftrace_hash(a->size_bits, a);
+	if (!sub)
+		goto error;

Again, this can be just return NULL;

ok

quoted

+
+	size = 1 << b->size_bits;
+	for (i = 0; i < size; i++) {

You can make this for (int i = 0; ...) too.

ok

quoted

+		hlist_for_each_entry(entry, &b->buckets[i], hlist) {
+			del = __ftrace_lookup_ip(sub, entry->ip);
+			if (WARN_ON_ONCE(!del))
+				goto error;

And you can remove the error label here too:

ok

			if (WARN_ON_ONCE(!del)) {
				free_ftrace_hash(sub);
				return NULL;
			}

quoted

+			remove_hash_entry(sub, del);
+			kfree(del);
+		}
+	}
+	return sub;
+
+ error:
+	free_ftrace_hash(sub);
+	return NULL;
+}
+
+int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
+{
+	struct ftrace_hash *old_direct_functions = NULL, *new_direct_functions;
+	struct ftrace_hash *old_filter_hash, *new_filter_hash = NULL;
+	struct ftrace_func_entry *del, *entry;

One variable per line.

ok

quoted

+	unsigned long size, i;
+	int err = -EINVAL;
+
+	if (!hash_count(hash))
+		return -EINVAL;
+	if (check_direct_multi(ops))
+		return -EINVAL;
+	if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
+		return -EINVAL;
+	if (direct_functions == EMPTY_HASH)
+		return -EINVAL;
+
+	mutex_lock(&direct_mutex);
+
+	old_filter_hash = ops->func_hash ? ops->func_hash->filter_hash : NULL;
+
+	if (!hash_count(old_filter_hash))
+		goto out_unlock;
+
+	/* Make sure requested entries are already registered. */
+	size = 1 << hash->size_bits;
+	for (i = 0; i < size; i++) {

	for (int i = 0; ...) 

ack

thanks,
jirka