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  • ovs源代码分析

    先整理粗稿,后面再细化。

    当调用ovs-vsctl add-port br-test eth0的时候调用netdev_create(datapath/vport-netdev.c),并通调用netdev_rx_handler_register注册设备收备报文后的处理方法:netdev_frame_hook。这样就能将接收报文将交给ovs处理,不走内核协议栈。

    netdev_port_receive->ovs_vport_receive

    void ovs_vport_receive(struct vport *vport, struct sk_buff *skb,
    		       struct ovs_key_ipv4_tunnel *tun_key)
    {
    	struct pcpu_sw_netstats *stats;
    
    	stats = this_cpu_ptr(vport->percpu_stats);
    	u64_stats_update_begin(&stats->syncp);
         //报文计数增加 stats->rx_packets++; stats->rx_bytes += skb->len; u64_stats_update_end(&stats->syncp); OVS_CB(skb)->tun_key = tun_key; ovs_dp_process_received_packet(vport, skb); }

    ovs_dp_process_received_packet-> ovs_dp_process_packet_with_key

    void ovs_dp_process_packet_with_key(struct sk_buff *skb,
    				    struct sw_flow_key *pkt_key,
    				    bool recirc)
    {
    	const struct vport *p = OVS_CB(skb)->input_vport;
    	struct datapath *dp = p->dp;
    	struct sw_flow *flow;
    	struct dp_stats_percpu *stats;
    	u64 *stats_counter;
    	u32 n_mask_hit;
    
    	stats = this_cpu_ptr(dp->stats_percpu);
    
    	/* Look up flow. */
         //查找内核态流表 flow = ovs_flow_tbl_lookup_stats(&dp->table, pkt_key, skb_get_hash(skb), &n_mask_hit);
         //未查询到内核态流表,使用netlink机制调用upcall将报文送到用户态处理并生成内核态流表 if (unlikely(!flow)) { struct dp_upcall_info upcall; upcall.cmd = OVS_PACKET_CMD_MISS; upcall.key = pkt_key; upcall.userdata = NULL; upcall.portid = ovs_vport_find_upcall_portid(p, skb); ovs_dp_upcall(dp, skb, &upcall); consume_skb(skb); stats_counter = &stats->n_missed; goto out; } OVS_CB(skb)->pkt_key = pkt_key; OVS_CB(skb)->flow = flow;      //匹配到内核态流表后执行对应的actions,对报文做处理。 ovs_flow_stats_update(OVS_CB(skb)->flow, pkt_key->tp.flags, skb); ovs_execute_actions(dp, skb, recirc); stats_counter = &stats->n_hit; out: /* Update datapath statistics. */ u64_stats_update_begin(&stats->sync); (*stats_counter)++; stats->n_mask_hit += n_mask_hit; u64_stats_update_end(&stats->sync); }

      

    综上所述,在接收报文后会有如下的函数调用。

    netdev_frame_hook-> netdev_port_receive ->ovs_skb_postpush_rcsum(?)-> ovs_vport_receive(数据统计变化) -> ovs_dp_process_received_packet->ovs_dp_process_packet_with_key->ovs_flow_tbl_lookup_stats(查找内核态,若失败则调用upcall查询用户态)->ovs_execute_actions

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  • 原文地址:https://www.cnblogs.com/haoqingchuan/p/6262927.html
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