net: flow_offload: add flow_block_cb_alloc() and flow_block_cb_free()

Add a new helper function to allocate flow_block_cb objects.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/flow_offload.h

@@ -260,6 +260,20 @@ struct flow_block_offload {
 	struct netlink_ext_ack *extack;
 };
 
+struct flow_block_cb {
+	struct list_head	list;
+	tc_setup_cb_t		*cb;
+	void			*cb_ident;
+	void			*cb_priv;
+	void			(*release)(void *cb_priv);
+	unsigned int		refcnt;
+};
+
+struct flow_block_cb *flow_block_cb_alloc(struct net *net, tc_setup_cb_t *cb,
+					  void *cb_ident, void *cb_priv,
+					  void (*release)(void *cb_priv));
+void flow_block_cb_free(struct flow_block_cb *block_cb);
+
 int flow_block_cb_setup_simple(struct flow_block_offload *f,
 			       struct list_head *driver_list, tc_setup_cb_t *cb,
 			       void *cb_ident, void *cb_priv, bool ingress_only);

net/core/flow_offload.c

@@ -166,6 +166,34 @@ void flow_rule_match_enc_opts(const struct flow_rule *rule,
 }
 EXPORT_SYMBOL(flow_rule_match_enc_opts);
 
+struct flow_block_cb *flow_block_cb_alloc(struct net *net, tc_setup_cb_t *cb,
+					  void *cb_ident, void *cb_priv,
+					  void (*release)(void *cb_priv))
+{
+	struct flow_block_cb *block_cb;
+
+	block_cb = kzalloc(sizeof(*block_cb), GFP_KERNEL);
+	if (!block_cb)
+		return ERR_PTR(-ENOMEM);
+
+	block_cb->cb = cb;
+	block_cb->cb_ident = cb_ident;
+	block_cb->cb_priv = cb_priv;
+	block_cb->release = release;
+
+	return block_cb;
+}
+EXPORT_SYMBOL(flow_block_cb_alloc);
+
+void flow_block_cb_free(struct flow_block_cb *block_cb)
+{
+	if (block_cb->release)
+		block_cb->release(block_cb->cb_priv);
+
+	kfree(block_cb);
+}
+EXPORT_SYMBOL(flow_block_cb_free);
+
 int flow_block_cb_setup_simple(struct flow_block_offload *f,
 			       struct list_head *driver_block_list,
 			       tc_setup_cb_t *cb, void *cb_ident, void *cb_priv,