【OVS2.5.0源码分析】datapath之流表创建过程

上一篇分析了流表查找过程，支撑流表查询的相关信息是什么时候建立，是怎么建立的将在本篇分析。 datapath流表更新的入口函数都定义在dp_flow_genl_ops中，流表创建的入口函数是ovs_flow_cmd_new函数，通过该函数，我们可以一窥流表相关信息的建立。

1、ovs_flow_cmd_new函数

static int ovs_flow_cmd_new(struct sk_buff *skb, struct genl_info *info)
{
	struct net *net = sock_net(skb->sk);
	struct nlattr **a = info->attrs;
	struct ovs_header *ovs_header = info->userhdr;
	struct sw_flow *flow = NULL, *new_flow;
	struct sw_flow_mask mask;
	struct sk_buff *reply;
	struct datapath *dp;
	struct sw_flow_key key;
	struct sw_flow_actions *acts;
	struct sw_flow_match match;
	u32 ufid_flags = ovs_nla_get_ufid_flags(a[OVS_FLOW_ATTR_UFID_FLAGS]);
	int error;
	bool log = !a[OVS_FLOW_ATTR_PROBE];

	/* Must have key and actions. */
	error = -EINVAL;
	if (!a[OVS_FLOW_ATTR_KEY]) {
		OVS_NLERR(log, "Flow key attr not present in new flow.");
		goto error;
	}
	if (!a[OVS_FLOW_ATTR_ACTIONS]) {
		OVS_NLERR(log, "Flow actions attr not present in new flow.");
		goto error;
	}

	/* Most of the time we need to allocate a new flow, do it before
	 * locking.
	 */
	new_flow = ovs_flow_alloc();
	if (IS_ERR(new_flow)) {
		error = PTR_ERR(new_flow);
		goto error;
	}

	/* Extract key. */
	ovs_match_init(&match, &key, &mask);
	error = ovs_nla_get_match(net, &match, a[OVS_FLOW_ATTR_KEY],         //完成key和match的信息设置
				  a[OVS_FLOW_ATTR_MASK], log);
	if (error)
		goto err_kfree_flow;

	ovs_flow_mask_key(&new_flow->key, &key, true, &mask);          //根据key和m