Openvswitch原理与代码分析(2): ovs-vswitchd的启动
ovs-vswitchd.c的main函数最终会进入一个while循环，在这个无限循环中，里面最重要的两个函数是bridge_run()和netdev_run()。Openvswitch主要管理两种类型的设备，一个是创建的虚拟网桥，一个是连接到虚拟网桥上的设备。
其中bridge_run就是初始化数据库中已经创建的虚拟网桥。
一、虚拟网桥的初始化bridge_run
bridge_run会调用bridge_run__，bridge_run__中最重要的是对于所有的网桥，都调用ofproto_run
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staticvoid
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bridge_run__(void)
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{
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……
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/* Let each bridge do the work that it needs to do. */
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HMAP_FOR_EACH (br, node, &all_bridges) {
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ofproto_run(br->ofproto);
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}
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}
Int ofproto_run(struct ofproto *p)会调用error = p->ofproto_class->run(p);
ofproto_class的定义在ofproto-provider.h中，它的实现定义在ofproto-dpif.c中，这里面的所有的函数，在这个文件中都有定义。
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conststruct ofproto_class ofproto_dpif_class = {
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init,
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enumerate_types,
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enumerate_names,
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del,
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port_open_type,
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type_run,
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type_wait,
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alloc,
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construct,
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destruct,
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dealloc,
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run,
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wait,
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NULL, /* get_memory_usage. */
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type_get_memory_usage,
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flush,
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query_tables,
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set_tables_version,
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port_alloc,
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port_construct,
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port_destruct,
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port_dealloc,
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port_modified,
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port_reconfigured,
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port_query_by_name,
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port_add,
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port_del,
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port_get_stats,
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port_dump_start,
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port_dump_next,
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port_dump_done,
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port_poll,
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port_poll_wait,
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port_is_lacp_current,
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port_get_lacp_stats,
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NULL, /* rule_choose_table */
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rule_alloc,
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rule_construct,
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rule_insert,
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rule_delete,
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rule_destruct,
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rule_dealloc,
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rule_get_stats,
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rule_execute,
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set_frag_handling,
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packet_out,
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set_netflow,
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get_netflow_ids,
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set_sflow,
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set_ipfix,
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set_cfm,
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cfm_status_changed,
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get_cfm_status,
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set_lldp,
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get_lldp_status,
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set_aa,
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aa_mapping_set,
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aa_mapping_unset,
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aa_vlan_get_queued,
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aa_vlan_get_queue_size,
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set_bfd,
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bfd_status_changed,
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get_bfd_status,
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set_stp,
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get_stp_status,
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set_stp_port,
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get_stp_port_status,
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get_stp_port_stats,
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set_rstp,
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get_rstp_status,
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set_rstp_port,
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get_rstp_port_status,
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set_queues,
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bundle_set,
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bundle_remove,
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mirror_set__,
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mirror_get_stats__,
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set_flood_vlans,
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is_mirror_output_bundle,
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forward_bpdu_changed,
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set_mac_table_config,
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set_mcast_snooping,
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set_mcast_snooping_port,
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set_realdev,
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NULL, /* meter_get_features */
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NULL, /* meter_set */
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NULL, /* meter_get */
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NULL, /* meter_del */
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group_alloc, /* group_alloc */
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group_construct, /* group_construct */
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group_destruct, /* group_destruct */
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group_dealloc, /* group_dealloc */
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group_modify, /* group_modify */
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group_get_stats, /* group_get_stats */
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get_datapath_version, /* get_datapath_version */
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};
在ofproto-provider.h中注释里是这样说的。
这里定义了四类数据结构
Struct ofproto表示一个交换机
Struct ofport表示交换机上的一个端口
Struct rule表示交换机上的一条flow规则
Struct ofgroup表示一个flow规则组
上面说到启动的过程中，会调用ofproto_class->run，也即会调用ofproto-dpif.c中的static int run(struct ofproto *ofproto_)函数。
在这个函数中，会初始化netflow, sflow, ipfix，stp, rstp, mac address learning等一系列操作。
bridge_run还会调用static void bridge_reconfigure(const struct ovsrec_open_vswitch *ovs_cfg)，其中ovs_cfg是从ovsdb-server里面读取出来的配置。
在这个函数里面，对于每一个网桥，将网卡添加进去
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HMAP_FOR_EACH (br, node, &all_bridges) {
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bridge_add_ports(br, &br->wanted_ports);
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shash_destroy(&br->wanted_ports);
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}
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staticvoid
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bridge_add_ports(struct bridge *br, conststruct shash *wanted_ports)
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{
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/* First add interfaces that request a particular port number. */
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bridge_add_ports__(br, wanted_ports, true);
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/* Then add interfaces that want automatic port number assignment.
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* We add these afterward to avoid accidentally taking a specifically
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* requested port number. */
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bridge_add_ports__(br, wanted_ports, false);
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}
static void bridge_add_ports__(struct bridge *br, const struct shash *wanted_ports, bool with_requested_port)会调用
static bool iface_create(struct bridge *br, const struct ovsrec_interface *iface_cfg, const struct ovsrec_port *port_cfg)会调用
static int iface_do_create(const struct bridge *br, const struct ovsrec_interface *iface_cfg, const struct ovsrec_port *port_cfg, ofp_port_t *ofp_portp, struct netdev **netdevp, char **errp)会调用
int ofproto_port_add(struct ofproto *ofproto, struct netdev *netdev, ofp_port_t *ofp_portp)会调用
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error = ofproto->ofproto_class->port_add(ofproto, netdev);
会调用ofproto-dpif.c中的ofproto_dpif_class的static int port_add(struct ofproto *ofproto_, struct netdev *netdev)函数。
会调用int dpif_port_add(struct dpif *dpif, struct netdev *netdev, odp_port_t *port_nop)会调用
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error = dpif->dpif_class->port_add(dpif, netdev, &port_no);
会调用dpif_netlink_class的port_add函数，也即dpif_netlink_port_add，也即
static int dpif_netlink_port_add(struct dpif *dpif_, struct netdev *netdev,odp_port_t *port_nop)会调用
static int dpif_netlink_port_add__(struct dpif_netlink *dpif, struct netdev *netdev, odp_port_t *port_nop)
在这个函数里面，会调用netlink的API，命令为OVS_VPORT_CMD_NEW
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constchar *name = netdev_vport_get_dpif_port(netdev,
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namebuf, sizeof namebuf);
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struct dpif_netlink_vport request, reply;
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struct nl_sock **socksp = NULL;
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if (dpif->handlers) {
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socksp = vport_create_socksp(dpif, &error);
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if (!socksp) {
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return error;
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}
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}
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dpif_netlink_vport_init(&request);
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request.cmd = OVS_VPORT_CMD_NEW;
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request.dp_ifindex = dpif->dp_ifindex;
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request.type = netdev_to_ovs_vport_type(netdev);
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request.name = name;
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upcall_pids = vport_socksp_to_pids(socksp, dpif->n_handlers);
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request.n_upcall_pids = socksp ? dpif->n_handlers : 1;
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request.upcall_pids = upcall_pids;
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error = dpif_netlink_vport_transact(&request, &reply, &buf);
这里会调用内核模块openvswitch.ko，在内核中添加虚拟网卡。这部分详细的过程将在下一节分析。
二、虚拟网卡的初始化netdev_run()
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void
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netdev_run(void)
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OVS_EXCLUDED(netdev_class_mutex, netdev_mutex)
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{
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struct netdev_registered_class *rc;
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netdev_initialize();
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ovs_mutex_lock(&netdev_class_mutex);
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HMAP_FOR_EACH (rc, hmap_node, &netdev_classes) {
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if (rc->class->run) {
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rc->class->run();
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}
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}
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ovs_mutex_unlock(&netdev_class_mutex);
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}
依次循环调用netdev_classes中的每一个run。
对于不同类型的虚拟网卡，都有对应的netdev_class。
例如对于dpdk的网卡有
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staticconststruct netdev_class dpdk_class =
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NETDEV_DPDK_CLASS(
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"dpdk",
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NULL,
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netdev_dpdk_construct,
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netdev_dpdk_destruct,
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netdev_dpdk_set_multiq,
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netdev_dpdk_eth_send,
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netdev_dpdk_get_carrier,
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netdev_dpdk_get_stats,
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netdev_dpdk_get_features,
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netdev_dpdk_get_status,
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netdev_dpdk_rxq_recv);
对于物理网卡，也需要有相应的netdev_class
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conststruct netdev_class netdev_linux_class =
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NETDEV_LINUX_CLASS(
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"system",
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netdev_linux_construct,
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netdev_linux_get_stats,
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netdev_linux_get_features,
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netdev_linux_get_status);
对于连接到KVM的tap网卡
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conststruct netdev_class netdev_tap_class =
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NETDEV_LINUX_CLASS(
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"tap",
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netdev_linux_construct_tap,
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netdev_tap_get_stats,
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netdev_linux_get_features,
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netdev_linux_get_status);
对于虚拟的软网卡，比如veth pair
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conststruct netdev_class netdev_internal_class =
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NETDEV_LINUX_CLASS(
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"internal",
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netdev_linux_construct,
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netdev_internal_get_stats,
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NULL, /* get_features */
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netdev_internal_get_status);
其中NETDEV_LINUX_CLASS是一个宏，不是所有的参数都需要全部填写。
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#define NETDEV_LINUX_CLASS(NAME, CONSTRUCT, GET_STATS, \
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GET_FEATURES, GET_STATUS) \
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{ \
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NAME, \
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\
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NULL, \
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netdev_linux_run, \
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netdev_linux_wait, \
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\
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netdev_linux_alloc, \
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CONSTRUCT, \
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netdev_linux_destruct, \
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netdev_linux_dealloc, \
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NULL, /* get_config */ \
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NULL, /* set_config */ \
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NULL, /* get_tunnel_config */ \
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NULL, /* build header */ \
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NULL, /* push header */ \
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NULL, /* pop header */ \
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NULL, /* get_numa_id */ \
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NULL, /* set_multiq */ \
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\
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netdev_linux_send, \
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netdev_linux_send_wait, \
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\
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netdev_linux_set_etheraddr, \
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netdev_linux_get_etheraddr, \
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netdev_linux_get_mtu, \
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netdev_linux_set_mtu, \
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netdev_linux_get_ifindex, \
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netdev_linux_get_carrier, \
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netdev_linux_get_carrier_resets, \
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netdev_linux_set_miimon_interval, \
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GET_STATS, \
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\
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GET_FEATURES, \
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netdev_linux_set_advertisements, \
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\
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netdev_linux_set_policing, \
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netdev_linux_get_qos_types, \
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netdev_linux_get_qos_capabilities, \
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netdev_linux_get_qos, \
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netdev_linux_set_qos, \
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netdev_linux_get_queue, \
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netdev_linux_set_queue, \
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netdev_linux_delete_queue, \
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netdev_linux_get_queue_stats, \
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netdev_linux_queue_dump_start, \
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netdev_linux_queue_dump_next, \
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netdev_linux_queue_dump_done, \
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netdev_linux_dump_queue_stats, \
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\
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netdev_linux_get_in4, \
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netdev_linux_set_in4, \
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netdev_linux_get_in6, \
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netdev_linux_add_router, \
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netdev_linux_get_next_hop, \
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GET_STATUS, \
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netdev_linux_arp_lookup, \
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\
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netdev_linux_update_flags, \
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\
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netdev_linux_rxq_alloc, \
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netdev_linux_rxq_construct, \
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netdev_linux_rxq_destruct, \
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netdev_linux_rxq_dealloc, \
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netdev_linux_rxq_recv, \
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netdev_linux_rxq_wait, \
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netdev_linux_rxq_drain, \
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}
rc->class->run()调用的是netdev-linux.c下的netdev_linux_run
netdev_linux_run会调用netlink的sock得到虚拟网卡的状态，并且更新状态。
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error = nl_sock_recv(sock, &buf, false);
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if (!error) {
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struct rtnetlink_change change;
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if (rtnetlink_parse(&buf, &change)) {
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struct netdev *netdev_ = netdev_from_name(change.ifname);
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if (netdev_ && is_netdev_linux_class(netdev_->netdev_class)) {
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struct netdev_linux *netdev = netdev_linux_cast(netdev_);
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ovs_mutex_lock(&netdev->mutex);
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netdev_linux_update(netdev, &change);
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ovs_mutex_unlock(&netdev->mutex);
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}
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netdev_close(netdev_);
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}
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}
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