Linux内核中流量控制(9)
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5.9 ingressingress流控方法是针对输入数据进行流控处理的，在net/sched/sch_ingress.c中定义, 使用时要求在内核配置中定义CONFIG_NET_CLS_ACT或CONFIG_NETFILTER，不过从代码实现看起来好象没什么意义。5.9.1 ingress操作结构定义// ingress私有数据结构struct ingress_qdisc_data {// 内部流控 struct Qdisc  *q;// 过滤规则 struct tcf_proto *filter_list;};// ingress流控操作结构static struct Qdisc_ops ingress_qdisc_ops = { .next  = NULL, .cl_ops  = &ingress_class_ops, .id  = "ingress", .priv_size = sizeof(struct ingress_qdisc_data), .enqueue = ingress_enqueue, .dequeue = ingress_dequeue, .requeue = ingress_requeue, .drop  = ingress_drop, .init  = ingress_init, .reset  = ingress_reset, .destroy = ingress_destroy,// 无change函数 .change  = NULL, .dump  = ingress_dump, .owner  = THIS_MODULE,}; // ingress类别操作结构static struct Qdisc_class_ops ingress_class_ops = { .graft  = ingress_graft, .leaf  = ingress_leaf, .get  = ingress_get, .put  = ingress_put, .change  = ingress_change, .delete  = NULL, .walk  = ingress_walk, .tcf_chain = ingress_find_tcf, .bind_tcf = ingress_bind_filter, .unbind_tcf = ingress_put, .dump  = NULL,};5.9.1 ingress的netfilter节点// 没定义NET_CLS_ACT, 而定义了NETFILTER的情况下才有效, 在netfilter节点中进行// 数据包是否接收的判断// 但如果定义了NET_CLS_ACT后, 该段代码无效#ifndef CONFIG_NET_CLS_ACT#ifdef CONFIG_NETFILTER/* after ipt_filter */static struct nf_hook_ops ing_ops = {// 钩子函数 .hook           = ing_hook, .owner  = THIS_MODULE, .pf             = PF_INET,// 挂接在PREROUTING点 .hooknum        = NF_IP_PRE_ROUTING,// 优先权NF_IP_PRI_FILTER + 1, 不过在PREROUTING点缺省好象没定义NF_IP_PRI_FILTER// 级别的节点 .priority       = NF_IP_PRI_FILTER + 1,};static struct nf_hook_ops ing6_ops = { .hook           = ing_hook, .owner  = THIS_MODULE, .pf             = PF_INET6, .hooknum        = NF_IP6_PRE_ROUTING, .priority       = NF_IP6_PRI_FILTER + 1,};static unsigned inting_hook(unsigned int hook, struct sk_buff **pskb,                             const struct net_device *indev,                             const struct net_device *outdev,                      int (*okfn)(struct sk_buff *)){  struct Qdisc *q; struct sk_buff *skb = *pskb;        struct net_device *dev = skb->dev;// 缺省动作, 接受 int fwres=NF_ACCEPT; DPRINTK("ing_hook: skb %s dev=%s len=%u\n",  skb->sk ? "(owned)" : "(unowned)",  skb->dev ? (*pskb)->dev->name : "(no dev)",  skb->len);/*revisit later: Use a private since lock dev->queue_lock is alsoused on the egress (might slow things for an iota)*/// 如果设备里定义了接收流控 if (dev->qdisc_ingress) {  spin_lock(&dev->queue_lock);  if ((q = dev->qdisc_ingress) != NULL)// 调用接收流控的入队函数, 返回值是对数据包的判断结果   fwres = q->enqueue(skb, q);  spin_unlock(&dev->queue_lock);        }// 如果没定义, 就直接返回缺省动作: 通过  return fwres;}#endif#endif5.9.3 初始化static int ingress_init(struct Qdisc *sch,struct rtattr *opt){ struct ingress_qdisc_data *p = PRIV(sch);/* Make sure either netfilter or preferably CLS_ACT is* compiled in */// 输入接收流控必须在内核选项中定义分类动作NET_CLS_ACT或NETFILTER#ifndef CONFIG_NET_CLS_ACT#ifndef CONFIG_NETFILTER// 两者都没定义的话就初始化失败 printk("You MUST compile classifier actions into the kernel\n"); return -EINVAL;#else// 使用NET_CLS_ACT优于使用NETFILTER printk("Ingress scheduler: Classifier actions prefered over netfilter\n");#endif#endif                                                                               #ifndef CONFIG_NET_CLS_ACT#ifdef CONFIG_NETFILTER// 没定义NET_CLS_ACT, 而定义了NETFILTER的情况// 登记输入流控的netfilter钩子节点函数 if (!nf_registered) {// 登记IPV4钩子节点  if (nf_register_hook(&ing_ops) < 0) {   printk("ingress qdisc registration error \n");   return -EINVAL;  }// 非0表示已经登记了  nf_registered++;// 登记IPV4钩子节点  if (nf_register_hook(&ing6_ops) < 0) {   printk("IPv6 ingress qdisc registration error, " \       "disabling IPv6 support.\n");  } else   nf_registered++; }#endif#endif DPRINTK("ingress_init(sch %p,[qdisc %p],opt %p)\n",sch,p,opt);// 初始内部流控初始化为noop, 丢包的 p->q = &noop_qdisc; return 0;} 5.9.5 入队sstatic int ingress_enqueue(struct sk_buff *skb,struct Qdisc *sch){// 接收流控私有数据 struct ingress_qdisc_data *p = PRIV(sch);// 分类结果 struct tcf_result res; int result; D2PRINTK("ingress_enqueue(skb %p,sch %p,[qdisc %p])\n", skb, sch, p);// 对数据进行分类 result = tc_classify(skb, p->filter_list, &res); D2PRINTK("result %d class 0x%04x\n", result, res.classid); /*  * Unlike normal "enqueue" functions, ingress_enqueue returns a  * firewall FW_* code.  */#ifdef CONFIG_NET_CLS_ACT// 在定义了NET_CLS_ACT的情况, 这时不会返回NF_*, 而是返回TC_ACT_* sch->bstats.packets++; sch->bstats.bytes += skb->len; switch (result) {  case TC_ACT_SHOT:// 丢包   result = TC_ACT_SHOT;   sch->qstats.drops++;   break;  case TC_ACT_STOLEN:  case TC_ACT_QUEUED:// 偷包, 重新处理   result = TC_ACT_STOLEN;   break;  case TC_ACT_RECLASSIFY:  case TC_ACT_OK:  case TC_ACT_UNSPEC:  default:// 接受, 计算tc_index   skb->tc_index = TC_H_MIN(res.classid);   result = TC_ACT_OK;   break; };/* backward compat */#else// 在没有定义了NET_CLS_ACT的情况, 这时存在netfilter节点, 返回NF_*结果#ifdef CONFIG_NET_CLS_POLICE // 在定义了NET_CLS_POLICE的情况 switch (result) {  case TC_POLICE_SHOT:// 丢包  result = NF_DROP;  sch->qstats.drops++;  break;  case TC_POLICE_RECLASSIFY: /* DSCP remarking here ? */  case TC_POLICE_OK:  case TC_POLICE_UNSPEC:  default:// 其他情况都是ACCEPT  sch->bstats.packets++;  sch->bstats.bytes += skb->len;  result = NF_ACCEPT;  break; };#else// 那两个NET_CLS选项都没定义的话直接ACCEPT D2PRINTK("Overriding result to ACCEPT\n"); result = NF_ACCEPT; sch->bstats.packets++; sch->bstats.bytes += skb->len;#endif#endif return result;} 5.9.6 重入队空函数static int ingress_requeue(struct sk_buff *skb,struct Qdisc *sch){/* struct ingress_qdisc_data *p = PRIV(sch); D2PRINTK("ingress_requeue(skb %p,sch %p,[qdisc %p])\n",skb,sch,PRIV(p));*/ return 0;} 5.9.7 出队// 空函数,因为不会有真正的dequeue操作static struct sk_buff *ingress_dequeue(struct Qdisc *sch){/* struct ingress_qdisc_data *p = PRIV(sch); D2PRINTK("ingress_dequeue(sch %p,[qdisc %p])\n",sch,PRIV(p));*/ return NULL;} 5.9.8 丢包// 基本也是空函数static unsigned int ingress_drop(struct Qdisc *sch){#ifdef DEBUG_INGRESS struct ingress_qdisc_data *p = PRIV(sch);#endif DPRINTK("ingress_drop(sch %p,[qdisc %p])\n", sch, p); return 0;} 5.9.9 复位sstatic void ingress_reset(struct Qdisc *sch){ struct ingress_qdisc_data *p = PRIV(sch); DPRINTK("ingress_reset(sch %p,[qdisc %p])\n", sch, p);/*#if 0*//* for future use */// 复位内部流控节点 qdisc_reset(p->q);/*#endif*/} 5.9.10 释放static void ingress_destroy(struct Qdisc *sch){// 私有数据 struct ingress_qdisc_data *p = PRIV(sch); struct tcf_proto *tp; DPRINTK("ingress_destroy(sch %p,[qdisc %p])\n", sch, p);// 释放TC过滤规则 while (p->filter_list) {  tp = p->filter_list;  p->filter_list = tp->next;  tcf_destroy(tp); }#if 0/* for future use */ qdisc_destroy(p->q);#endif}5.9.11 输出参数static int ingress_dump(struct Qdisc *sch, struct sk_buff *skb){ unsigned char *b = skb->tail; struct rtattr *rta; rta = (struct rtattr *) b;// 起始什么数据也没有 RTA_PUT(skb, TCA_OPTIONS, 0, NULL); rta->rta_len = skb->tail - b; return skb->len;rtattr_failure: skb_trim(skb, b - skb->data); return -1;}5.9.13 ingress类别操作// 嫁接, 增加叶子节点// 基本是空函数, 恒返回1static int ingress_graft(struct Qdisc *sch,unsigned long arg,    struct Qdisc *new,struct Qdisc **old){#ifdef DEBUG_INGRESS struct ingress_qdisc_data *p = PRIV(sch);#endif DPRINTK("ingress_graft(sch %p,[qdisc %p],new %p,old %p)\n",  sch, p, new, old); DPRINTK("\n ingress_graft: You cannot add qdiscs to classes");        return 1;}// 叶子, 空函数static struct Qdisc *ingress_leaf(struct Qdisc *sch, unsigned long arg){ return NULL;}// 计数增加, 使用类别ID计算static unsigned long ingress_get(struct Qdisc *sch,u32 classid){#ifdef DEBUG_INGRESS struct ingress_qdisc_data *p = PRIV(sch);#endif DPRINTK("ingress_get(sch %p,[qdisc %p],classid %x)\n", sch, p, classid); return TC_H_MIN(classid) + 1;}// 绑定TC过滤规则表static unsigned long ingress_bind_filter(struct Qdisc *sch,    unsigned long parent, u32 classid){ return ingress_get(sch, classid);}// 计数减少, 空函数static void ingress_put(struct Qdisc *sch, unsigned long cl){}// 空函数static int ingress_change(struct Qdisc *sch, u32 classid, u32 parent,    struct rtattr **tca, unsigned long *arg){#ifdef DEBUG_INGRESS struct ingress_qdisc_data *p = PRIV(sch);#endif DPRINTK("ingress_change(sch %p,[qdisc %p],classid %x,parent %x),"  "arg 0x%lx\n", sch, p, classid, parent, *arg); DPRINTK("No effect. sch_ingress doesn't maintain classes at the moment"); return 0;} // 遍历, 空函数static void ingress_walk(struct Qdisc *sch,struct qdisc_walker *walker){#ifdef DEBUG_INGRESS struct ingress_qdisc_data *p = PRIV(sch);#endif DPRINTK("ingress_walk(sch %p,[qdisc %p],walker %p)\n", sch, p, walker); DPRINTK("No effect. sch_ingress doesn't maintain classes at the moment");}// 获取TC过滤规则表static struct tcf_proto **ingress_find_tcf(struct Qdisc *sch,unsigned long cl){ struct ingress_qdisc_data *p = PRIV(sch); return &p->filter_list;} ...... 待续 ......