dpvs之l2层数据包处理

• 二层数据报处理入口函数

void lcore_process_packets(struct netif_queue_conf *qconf, struct rte_mbuf **mbufs,lcoreid_t cid, uint16_t count, bool pkts_from_ring)
{int i, t;struct ether_hdr *eth_hdr;struct rte_mbuf * mbuf_copied = NULL;/* prefetch packets *///prefetch预取一定数量的mbuf，主要提高cache命中率，提高效率for (t = 0; t < count && t < NETIF_PKT_PREFETCH_OFFSET; t++){rte_prefetch0(rte_pktmbuf_mtod(mbufs[t], void *));}/* L2 filter */for (i = 0; i < count; i++){struct rte_mbuf *mbuf = mbufs[i];//获取数据包对应的网课信息struct netif_port *dev = netif_port_get(mbuf->port);//如果未找到对应的net_device层设备,释放数据报,更新统计信息if (unlikely(!dev)){rte_pktmbuf_free(mbuf);lcore_stats[cid].dropped++;continue;}//处理网卡是bond情况,将net_device设备更改为绑定至的设备if (dev->type == PORT_TYPE_BOND_SLAVE){dev        = dev->bond->slave.master;mbuf->port = dev->id;}//在处理当前数据包同时，预取接下来处理数据包if (t < count){rte_prefetch0(rte_pktmbuf_mtod(mbufs[t], void *));t++;}//获取以太网头,并判断当前二层包类型,本机RTE_ETH_PKT_HOST,广播或组播等eth_hdr = rte_pktmbuf_mtod(mbuf, struct ether_hdr *);/* reuse mbuf.packet_type, it was RTE_PTYPE_XXX */mbuf->packet_type = eth_type_parse(eth_hdr, dev);/** In NETIF_PORT_FLAG_FORWARD2KNI mode.* All packets received are deep copied and sent to  KNI* for the purpose of capturing forwarding packets.Since the* rte_mbuf will be modified in the following procedure,* we should use mbuf_copy instead of rte_pktmbuf_clone.*///kni模式的所有的包都要透传到内核,深拷贝一份if (dev->flag & NETIF_PORT_FLAG_FORWARD2KNI){if (likely(NULL != (mbuf_copied = mbuf_copy(mbuf,pktmbuf_pool[dev->socket])))){kni_ingress(mbuf_copied, dev, qconf);}else{RTE_LOG(WARNING, NETIF, "%s: Failed to copy mbuf\\n",__func__);}}/** do not drop pkt to other hosts (ETH_PKT_OTHERHOST)* since virtual devices may have different MAC with* underlying device.*//** handle VLAN* if HW offload vlan strip, it's still need vlan module* to act as VLAN filter.*///兼容处理vlan的情况,如果下层协议是vlan,或者vlan已经被硬件负载功能stripped,进行vlan处理if (eth_hdr->ether_type == htons(ETH_P_8021Q) ||mbuf->ol_flags & PKT_RX_VLAN_STRIPPED){//vlan处理失败,释放数据报,更新统计信息if (vlan_rcv(mbuf, netif_port_get(mbuf->port)) != EDPVS_OK){rte_pktmbuf_free(mbuf);lcore_stats[cid].dropped++;continue;}//获取对应的dev设备,在vlan_rcv中mbuf->port会变更改为对应vlanid的port号，所以此处重新获取devdev = netif_port_get(mbuf->port);if (unlikely(!dev)){rte_pktmbuf_free(mbuf);lcore_stats[cid].dropped++;continue;}//重新获取eth_hdr,未启用vlan_stripped硬件负载功能时,会移除vlan信息,导致eth_hdr->ether_type发生变更eth_hdr = rte_pktmbuf_mtod(mbuf, struct ether_hdr *);}/* handler should free mbuf *///数据包转发函数netif_deliver_mbuf(mbuf, eth_hdr->ether_type, dev, qconf,(dev->flag & NETIF_PORT_FLAG_FORWARD2KNI) ? true : false,cid, pkts_from_ring);//更新统计数据lcore_stats[cid].ibytes += mbuf->pkt_len;lcore_stats[cid].ipackets++;}
}

• netif_deliver_mbuf

  • 二层数据包分发，包括kni，arp数据报广播，和pkt_type查找

  static inline int netif_deliver_mbuf(struct rte_mbuf *mbuf,uint16_t eth_type,struct netif_port *dev,struct netif_queue_conf *qconf,bool forward2kni,lcoreid_t cid,bool pkts_from_ring)
  {struct pkt_type *pt;int      err;uint16_t data_off;//校验相关assert(mbuf->port <= NETIF_MAX_PORTS);assert(dev != NULL);//pkt_type对应L3层处理函数,比如arp_pkt_type,ipv4_pkt_typept = pkt_type_get(eth_type, dev);//pt为空说明没有对应协议的处理if (NULL == pt){//如果没有转发过,则转发到kni,否则释放数据包if (!forward2kni){kni_ingress(mbuf, dev, qconf);}else{rte_pktmbuf_free(mbuf);}return(EDPVS_OK);}/*clone arp pkt to every queue*///如果是 arp 类型的包，复制拷到所有队列。这块为什么这么处理呢？猜测，dpdk 程序是每个核都有本地变量，无锁的，所以邻居//子系统也要每个核都是全量的if (pt->type == rte_cpu_to_be_16(ETHER_TYPE_ARP) && !pkts_from_ring){struct rte_mempool *mbuf_pool;struct rte_mbuf *   mbuf_clone;uint8_t             i;struct arp_hdr *    arp;unsigned            socket_id;socket_id = rte_socket_id();mbuf_pool = pktmbuf_pool[socket_id];rte_pktmbuf_adj(mbuf, sizeof(struct ether_hdr));arp = rte_pktmbuf_mtod(mbuf, struct arp_hdr *);rte_pktmbuf_prepend(mbuf, (uint16_t)sizeof(struct ether_hdr));//判断arp_op是否是ARP_OP_REPLY，是的话，需要clone mbuf，然后调用rte_ring_enqueue发送到其他每个核一份if (rte_be_to_cpu_16(arp->arp_op) == ARP_OP_REPLY){for (i = 0; i < DPVS_MAX_LCORE; i++){if ((i == cid) || (!is_lcore_id_fwd(i)) ||(i == rte_get_master_lcore())){continue;}/*rte_pktmbuf_clone will not clone pkt.data, just copy pointer!*/mbuf_clone = rte_pktmbuf_clone(mbuf, mbuf_pool);if (mbuf_clone){int ret = rte_ring_enqueue(arp_ring[i], mbuf_clone);if (unlikely(-EDQUOT == ret)){RTE_LOG(WARNING, NETIF, "%s: arp ring of lcore %d quota exceeded\\n",__func__, i);}else if (ret < 0){RTE_LOG(WARNING, NETIF, "%s: arp ring of lcore %d enqueue failed\\n",__func__, i);rte_pktmbuf_free(mbuf_clone);}}}}}//设置l2层数据长度mbuf->l2_len = sizeof(struct ether_hdr);/* Remove ether_hdr at the beginning of an mbuf */data_off = mbuf->data_off;//调整mbuf指向三层首部,数据包一直往上传递时,直接指向当前层的开头,避免多次解析数据包//长度校验,此处是否忘记释放数据包if (unlikely(NULL == rte_pktmbuf_adj(mbuf, sizeof(struct ether_hdr)))){return(EDPVS_INVPKT);}//执行pkt_type对应处理函数,如果ipv4则对应ipv4_rcverr = pt->func(mbuf, dev);//是否需要通过kni传递至linux 内核处理if (err == EDPVS_KNICONTINUE){//如果不是本地lcore收到的数据报,或者已经传递过forward2kni,则直接释放,防止重复数据报传递至内核if (pkts_from_ring || forward2kni){rte_pktmbuf_free(mbuf);return(EDPVS_OK);}//此处将数据包的起始地址进行复原,在传递至L3层之前,data_off记录了原始的mbuf data起始地址if (likely(NULL != rte_pktmbuf_prepend(mbuf,(mbuf->data_off - data_off)))){kni_ingress(mbuf, dev, qconf);}else{rte_pktmbuf_free(mbuf);}}return(EDPVS_OK);
  }