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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()。
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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。
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其中bridge_run就是初始化数据库中已经创建的虚拟网桥。
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一、虚拟网桥的初始化bridge_run
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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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static
void
bridge_run__(void)
{
……
????/* Let each bridge do the work that it needs to do. */
????HMAP_FOR_EACH (br, node, &all_bridges) {
????????ofproto_run(br->ofproto);
????}
}
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Int ofproto_run(struct ofproto *p)会调用error = p->ofproto_class->run(p);
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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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const
struct ofproto_class ofproto_dpif_class = {
????init,
????enumerate_types,
????enumerate_names,
????del,
????port_open_type,
????type_run,
????type_wait,
????alloc,
????construct,
????destruct,
????dealloc,
????run,
????wait,
????NULL, /* get_memory_usage. */
????type_get_memory_usage,
????flush,
????query_tables,
????set_tables_version,
????port_alloc,
????port_construct,
????port_destruct,
????port_dealloc,
????port_modified,
????port_reconfigured,
????port_query_by_name,
????port_add,
????port_del,
????port_get_stats,
????port_dump_start,
????port_dump_next,
????port_dump_done,
????port_poll,
????port_poll_wait,
????port_is_lacp_current,
????port_get_lacp_stats,
????NULL, /* rule_choose_table */
????rule_alloc,
????rule_construct,
????rule_insert,
????rule_delete,
????rule_destruct,
????rule_dealloc,
????rule_get_stats,
????rule_execute,
????set_frag_handling,
????packet_out,
????set_netflow,
????get_netflow_ids,
????set_sflow,
????set_ipfix,
????set_cfm,
????cfm_status_changed,
????get_cfm_status,
????set_lldp,
????get_lldp_status,
????set_aa,
????aa_mapping_set,
????aa_mapping_unset,
????aa_vlan_get_queued,
????aa_vlan_get_queue_size,
????set_bfd,
????bfd_status_changed,
????get_bfd_status,
????set_stp,
????get_stp_status,
????set_stp_port,
????get_stp_port_status,
????get_stp_port_stats,
????set_rstp,
????get_rstp_status,
????set_rstp_port,
????get_rstp_port_status,
????set_queues,
????bundle_set,
????bundle_remove,
????mirror_set__,
????mirror_get_stats__,
????set_flood_vlans,
????is_mirror_output_bundle,
????forward_bpdu_changed,
????set_mac_table_config,
????set_mcast_snooping,
????set_mcast_snooping_port,
????set_realdev,
????NULL, /* meter_get_features */
????NULL, /* meter_set */
????NULL, /* meter_get */
????NULL, /* meter_del */
????group_alloc, /* group_alloc */
????group_construct, /* group_construct */
????group_destruct, /* group_destruct */
????group_dealloc, /* group_dealloc */
????group_modify, /* group_modify */
????group_get_stats, /* group_get_stats */
????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
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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。
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在这个函数中，会初始化netflow, sflow, ipfix，stp, rstp, mac address learning等一系列操作。
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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。
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在这个函数里面，对于每一个网桥，将网卡添加进去
HMAP_FOR_EACH (br, node, &all_bridges) {
????bridge_add_ports(br, &br->wanted_ports);
????shash_destroy(&br->wanted_ports);
}
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static
void
bridge_add_ports(struct bridge *br, const
struct shash *wanted_ports)
{
????/* First add interfaces that request a particular port number. */
????bridge_add_ports__(br, wanted_ports, true);
? ????/* Then add interfaces that want automatic port number assignment.
?????* We add these afterward to avoid accidentally taking a specifically
?????* requested port number. */
????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);
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会调用ofproto-dpif.c中的ofproto_dpif_class的static int port_add(struct ofproto *ofproto_, struct netdev *netdev)函数。
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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);
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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)
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在这个函数里面，会调用netlink的API，命令为OVS_VPORT_CMD_NEW
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const
char *name = netdev_vport_get_dpif_port(netdev,
??????????????????????????????????????????????????namebuf, sizeof namebuf);
struct dpif_netlink_vport request, reply;
struct nl_sock **socksp = NULL;
? if (dpif->handlers) {
????socksp = vport_create_socksp(dpif, &error);
????if (!socksp) {
????????return error;
????}
}
? dpif_netlink_vport_init(&request);
request.cmd = OVS_VPORT_CMD_NEW;
request.dp_ifindex = dpif->dp_ifindex;
request.type = netdev_to_ovs_vport_type(netdev);
? request.name = name;
? upcall_pids = vport_socksp_to_pids(socksp, dpif->n_handlers);
request.n_upcall_pids = socksp ? dpif->n_handlers : 1;
request.upcall_pids = upcall_pids;
error = dpif_netlink_vport_transact(&request, &reply, &buf);
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二、虚拟网卡的初始化netdev_run()
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void
netdev_run(void)
????OVS_EXCLUDED(netdev_class_mutex, netdev_mutex)
{
????struct netdev_registered_class *rc;
? ????netdev_initialize();
????ovs_mutex_lock(&netdev_class_mutex);
????HMAP_FOR_EACH (rc, hmap_node, &netdev_classes) {
????????if (rc->class->run) {
????????????rc->class->run();
????????}
????}
????ovs_mutex_unlock(&netdev_class_mutex);
}
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依次循环调用netdev_classes中的每一个run。
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对于不同类型的虚拟网卡，都有对应的netdev_class。
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例如对于dpdk的网卡有
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static
const
struct netdev_class dpdk_class =
????NETDEV_DPDK_CLASS(
????????"dpdk",
????????NULL,
????????netdev_dpdk_construct,
????????netdev_dpdk_destruct,
????????netdev_dpdk_set_multiq,
????????netdev_dpdk_eth_send,
????????netdev_dpdk_get_carrier,
????????netdev_dpdk_get_stats,
????????netdev_dpdk_get_features,
????????netdev_dpdk_get_status,
????????netdev_dpdk_rxq_recv);
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对于物理网卡，也需要有相应的netdev_class
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const
struct netdev_class netdev_linux_class =
????NETDEV_LINUX_CLASS(
????????"system",
????????netdev_linux_construct,
????????netdev_linux_get_stats,
????????netdev_linux_get_features,
????????netdev_linux_get_status);
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对于连接到KVM的tap网卡
const
struct netdev_class netdev_tap_class =
????NETDEV_LINUX_CLASS(
????????"tap",
????????netdev_linux_construct_tap,
????????netdev_tap_get_stats,
????????netdev_linux_get_features,
????????netdev_linux_get_status);
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对于虚拟的软网卡，比如veth pair
const
struct netdev_class netdev_internal_class =
????NETDEV_LINUX_CLASS(
????????"internal",
????????netdev_linux_construct,
????????netdev_internal_get_stats,
????????NULL, /* get_features */
????????netdev_internal_get_status);
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其中NETDEV_LINUX_CLASS是一个宏，不是所有的参数都需要全部填写。
#define NETDEV_LINUX_CLASS(NAME, CONSTRUCT, GET_STATS, ???????????????????????????GET_FEATURES, GET_STATUS) { ????NAME, ???????????????????????????????????????????????????????????????? ????NULL, ????netdev_linux_run, ????netdev_linux_wait, ???????????????????????????????????????????????????????????????? ????netdev_linux_alloc, ????CONSTRUCT, ????netdev_linux_destruct, ????netdev_linux_dealloc, ????NULL, /* get_config */ ????NULL, /* set_config */ ????NULL, /* get_tunnel_config */ ????NULL, /* build header */ ????NULL, /* push header */ ????NULL, /* pop header */ ????NULL, /* get_numa_id */ ????NULL, /* set_multiq */ ???????????????????????????????????????????????????????????????? ????netdev_linux_send, ????netdev_linux_send_wait, ???????????????????????????????????????????????????????????????? ????netdev_linux_set_etheraddr, ????netdev_linux_get_etheraddr, ????netdev_linux_get_mtu, ????netdev_linux_set_mtu, ????netdev_linux_get_ifindex, ????netdev_linux_get_carrier, ????netdev_linux_get_carrier_resets, ????netdev_linux_set_miimon_interval, ????GET_STATS, ???????????????????????????????????????????????????????????????? ????GET_FEATURES, ????netdev_linux_set_advertisements, ???????????????????????????????????????????????????????????????? ????netdev_linux_set_policing, ????netdev_linux_get_qos_types, ????netdev_linux_get_qos_capabilities, ????netdev_linux_get_qos, ????netdev_linux_set_qos, ????netdev_linux_get_queue, ????netdev_linux_set_queue, ????netdev_linux_delete_queue, ????netdev_linux_get_queue_stats, ????netdev_linux_queue_dump_start, ????netdev_linux_queue_dump_next, ????netdev_linux_queue_dump_done, ????netdev_linux_dump_queue_stats, ???????????????????????????????????????????????????????????????? ????netdev_linux_get_in4, ????netdev_linux_set_in4, ????netdev_linux_get_in6, ????netdev_linux_add_router, ????netdev_linux_get_next_hop, ????GET_STATUS, ????netdev_linux_arp_lookup, ???????????????????????????????????????????????????????????????? ????netdev_linux_update_flags, ???????????????????????????????????????????????????????????????? ????netdev_linux_rxq_alloc, ????netdev_linux_rxq_construct, ????netdev_linux_rxq_destruct, ????netdev_linux_rxq_dealloc, ????netdev_linux_rxq_recv, ????netdev_linux_rxq_wait, ????netdev_linux_rxq_drain, }
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rc->class->run()调用的是netdev-linux.c下的netdev_linux_run
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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);
if (!error) {
????struct rtnetlink_change change;
????if (rtnetlink_parse(&buf, &change)) {
????????struct netdev *netdev_ = netdev_from_name(change.ifname);
????????if (netdev_ && is_netdev_linux_class(netdev_->netdev_class)) {
???????????struct netdev_linux *netdev = netdev_linux_cast(netdev_);
???????????ovs_mutex_lock(&netdev->mutex);
???????????netdev_linux_update(netdev, &change);
???????????ovs_mutex_unlock(&netdev->mutex);
????????}
????????netdev_close(netdev_);
?????}
}
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Openvswitch原理与代码分析(2): ovs-vswitchd的启动
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原文地址：http://www.cnblogs.com/popsuper1982/p/5851603.html
