处理完毕后会得到多个flow_miss。
结构体dpif_upcall代表的是由内核传到用户空间的一个包，包含上传原因，packet data。以及以netlink attr形式存在的键值。 struct dpif_upcall { /* All types. */ enum dpif_upcall_type type; struct ofpbuf *packet; /* Packet data. */ struct nlattr *key; /* Flow key. */ size_t key_len; /* Length of 'key' in bytes. */ /* DPIF_UC_ACTION only. */ uint64_t userdata; /* Argument to OVS_ACTION_ATTR_USERSPACE. */ }; 结构体flow_miss是将具有同样流特征的packets统一起来（ batching），性能可能会更优，所以这个结构体要将datapath interface相关的数据队列起来。每一个flow_miss相应的是发送的一个或多个数据包，另外可能会在dpif中安装流项。 struct flow_miss { struct hmap_node hmap_node; struct flow flow; //流特征。 enum odp_key_fitness key_fitness; const struct nlattr *key; size_t key_len; ovs_be16 initial_tci; struct list packets; //具有该流特征的全部的packets； enum dpif_upcall_type upcall_type; }; 2. 接下来。函数handle_miss_upcalls（）会依次遍历这个flow_misses数组，完毕的工作有：1）得到odp_key_fitness （也就是内核层/用户层在流匹配上的一致程度）；2）从packet data中析取出流信息miss->flow。3）然后对miss->flow进行哈希。假设不存在则插入到TO-DO-List中。4）将这个upcall->packet插入到对应的节点上。 3.然后对于TO-DO-List中的每一个元素，调用handle_flow_miss（）函数。它会从这个flow_miss中构造得到flow_miss_op，详细的过程是：1）查询ofproto的facet表ofproto->facets看针对这个flow的facet是否已存在。2）从ofproto的分类表中查找与这个flow相应的分类规则，对于第一个进入系统的包，还没有建立起cls_rule。此时返回ofproto->miss_rule（ 是怎样初始化的呢？）；3）构造一个facet，和当前的flow和rule_dpif关联起来；4）这时候与flow_miss 匹配的facet也有了，接着呼叫函数 handle_flow_miss_with_facet（）可能会添加须要的操作到flow_miss_op中。详细过程是：先是通过内核传上来的key找subfacet是否存在，假设不存在就构建一个；然后针对每一个连接到这个flow_miss中的packet进行分别处理；handle_flow_miss_common（）会推断假设rule->up.cr.priority = FAIL_OPEN_PRIORITY的话就会发送一个packetin到SDN Controller；对于刚创建的subfacet，其actions为空，所以函数subfacet_make_actions（）会依据subfacet中的rule来创建datapath action，存储在odp_actions中。假设upcall的类型是DPIF_UC_MISS。就创建一个DPIF_OP_FLOW_PUT类型的flow_miss_op（即dpif_flow_put），然后compose_slow_path（）会构建一个用户空间的user_action_cookie，它的类型是USER_ACTION_COOKIE_SLOW_PATH 表示这个流得到了用户空间的处理。然后-> odp_put_userspace_action() 会添加一个OVS_ACTION_ATTR_USERSPACE action到odp_actions中，属性值包含netlink pid 和 刚才的cookie。 struct flow_miss_op { struct dpif_op dpif_op; //据此能够得到操作类型handler； struct subfacet *subfacet; // Subfacet ，据此能够得到全部的flow和rule等数据。 void *garbage; /* Pointer to pass to free(), NULL if none. */ uint64_t stub[1024 / 8]; /* Temporary buffer. */ }; struct dpif_op { enum dpif_op_type type; int error; union { struct dpif_flow_put flow_put; struct dpif_flow_del flow_del; struct dpif_execute execute; } u; }; enum dpif_op_type { DPIF_OP_FLOW_PUT = 1, DPIF_OP_FLOW_DEL, DPIF_OP_EXECUTE, }; 结构体facet是openflow flow的全然匹配（ exact-match）的实例抽象。它与"struct flow"关联。代表OVS用户空间对于exact match flow的观点。有一个或多个subfacet。每一个subfacet追踪着内核层datapath对于这个exact-match flow 的观点。当内核层和用户空间对一个flow key观点一致的时候，就仅仅有一个subfacet（通常如此）。很多其它理解參考[]。 struct facet { /* Owners. */ struct hmap_node hmap_node; /* In owning ofproto's 'facets' hmap. */ struct list list_node; /* In owning rule's 'facets' list. */ struct rule_dpif *rule; /* Owning rule. */ /* Owned data. */ struct list subfacets; long long int used; /* Time last used; time created if not used. */ /* Key. */ struct flow flow; // 接下来是 一些统计字段； /* Storage for a single subfacet, to reduce malloc() time and space * overhead. (A facet always has at least one subfacet and in the common * case has exactly one subfacet.) */ struct subfacet one_subfacet; }; struct rule_dpif { struct rule up; uint64_t packet_count; /* Number of packets received. */ uint64_t byte_count; /* Number of bytes received. */ tag_type tag; /* Caches rule_calculate_tag() result. */ struct list facets; /* List of "struct facet"s. */ }; /* An OpenFlow flow within a "struct ofproto". * * With few exceptions, ofproto implementations may look at these fields but * should not modify them. */ struct rule { struct list ofproto_node; /* Owned by ofproto base code. */ struct ofproto *ofproto; /* The ofproto that contains this rule. */ struct cls_rule cr; /* In owning ofproto's classifier. */ struct ofoperation *pending; /* Operation now in progress, if nonnull. */ ovs_be64 flow_cookie; /* Controller-issued identifier. */ long long int created; /* Creation time. */ long long int modified; /* Time of last modification. */ long long int used; /* Last use; time created if never used. */ uint16_t hard_timeout; /* In seconds from ->modified. */ uint16_t idle_timeout; /* In seconds from ->used. */ uint8_t table_id; /* Index in ofproto's 'tables' array. */ bool send_flow_removed; /* Send a flow removed message? */ /* Eviction groups. */ bool evictable; /* If false, prevents eviction. */ struct heap_node evg_node; /* In eviction_group's "rules" heap. */ struct eviction_group *eviction_group; /* NULL if not in any group. */ struct ofpact *ofpacts; /* Sequence of "struct ofpacts". */ unsigned int ofpacts_len; /* Size of 'ofpacts', in bytes. */ /* Flow monitors. */ enum nx_flow_monitor_flags monitor_flags; uint64_t add_seqno; /* Sequence number when added. */ uint64_t modify_seqno; /* Sequence number when changed. */ }; struct subfacet { /* Owners. */ struct hmap_node hmap_node; /* In struct ofproto_dpif 'subfacets' list. */ struct list list_node; /* In struct facet's 'facets' list. */ struct facet *facet; /* Owning facet. */ /* Key. * * To save memory in the common case, 'key' is NULL if 'key_fitness' is * ODP_FIT_PERFECT, that is, odp_flow_key_from_flow() can accurately * regenerate the ODP flow key from ->facet->flow. */ enum odp_key_fitness key_fitness; struct nlattr *key; int key_len; long long int used; /* Time last used; time created if not used. */ uint64_t dp_packet_count; /* Last known packet count in the datapath. */ uint64_t dp_byte_count; /* Last known byte count in the datapath. */ /* Datapath actions. * * These should be essentially identical for every subfacet in a facet, but * may differ in trivial ways due to VLAN splinters. */ size_t actions_len; /* Number of bytes in actions[]. */ struct nlattr *actions; /* Datapath actions. */ enum slow_path_reason slow; /* 0 if fast path may be used. */ enum subfacet_path path; /* Installed in datapath? */ }; 枚举体slow_path_reason 列举的是packet没有在内核层被转发的原因（也就是说这个packet是fast path）。 enum slow_path_reason { /* These reasons are mutually exclusive. */ SLOW_CFM = 1 << 0, /* CFM packets need per-packet processing. */ SLOW_LACP = 1 << 1, /* LACP packets need per-packet processing. */ SLOW_STP = 1 << 2, /* STP packets need per-packet processing. */ SLOW_IN_BAND = 1 << 3, /* In-band control needs every packet. */ // 和 SLOW_CFM, SLOW_LACP, SLOW_STP相互排斥，能够和SLOW_IN_BAND组合。 SLOW_CONTROLLER = 1 << 4, /* Packets must go to OpenFlow controller. */ }; 枚举体subfacet_path列举的是其可能的当前状态：1）SF_NOT_INSTALLED表示没有安装在datapath中，这样的情况出如今这个subfacet构建之后，销毁之前，或者当我们在安装一个subfacet到datapath时出错。由于subfacet中相应的有action，所以这里的facet install指的是datapath运行了由用户空间下发的详细action。2）SF_FAST_PATH说明相应的action已经得到了运行，packets能够在内核层直接转发；3）SF_SLOW_PATH是流规则指定了要发往用户空间。 enum subfacet_path { SF_NOT_INSTALLED, /* No datapath flow for this subfacet. */ SF_FAST_PATH, /* Full actions are installed. */ SF_SLOW_PATH, /* Send-to-userspace action is installed. */ }; 4. 通过上面的操作，flow_miss_op数组就得到了。接下来调用函数 dpif_operate() 依次对dpif运行这些operation。 for (i = 0; i < n_ops; i++) { struct dpif_op *op = ops[i]; switch (op->type) { case DPIF_OP_FLOW_PUT: op->error = dpif_flow_put__(dpif, &op->u.flow_put); break; case DPIF_OP_FLOW_DEL: op->error = dpif_flow_del__(dpif, &op->u.flow_del); break; case DPIF_OP_EXECUTE: op->error = dpif_execute__(dpif, &op->u.execute); break; default: NOT_REACHED(); } 这里就看flow put的情况，用户空间会通过genl把对应的动作下发给内核datapath，而且接收响应。 转载请注明出处谢谢： http://blog.csdn.net/vonzhoufz/article/details/29359299版权声明：本文博主原创文章，博客，未经同意不得转载。
转载于:https://www.cnblogs.com/gcczhongduan/p/4889476.html
