路由2 【转载: 再议路由初始化】

  1 看源代码，发现路由最初初始化的函数在net/ipv4/route.c
  2 int __init ip_rt_init(void)
  3 {
  4     int rc = 0;
  5 
  6 #ifdef CONFIG_NET_CLS_ROUTE
  7     ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct));
  8     if (!ip_rt_acct)
  9         panic("IP: failed to allocate ip_rt_acct\n");
 10 #endif
 11     
 12     /*既然是全局变量，肯定很重要*/
 13     ipv4_dst_ops.kmem_cachep =
 14         kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
 15                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
 16 
 17     ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
 18 
 19     /*创建struct rt_hash_bucket 类型的哈希表*/
 20     rt_hash_table = (struct rt_hash_bucket *)
 21         alloc_large_system_hash("IP route cache",
 22                     sizeof(struct rt_hash_bucket),
 23                     rhash_entries,
 24                     (num_physpages >= 128 * 1024) ? 15 : 17,
 25                     0,
 26                     &rt_hash_log,
 27                     &rt_hash_mask,
 28                     0);
 29     memset(rt_hash_table, 0, (rt_hash_mask + 1) * sizeof(struct rt_hash_bucket));
 30     rt_hash_lock_init();
 31 
 32     /*垃圾回收阀值*/
 33     ipv4_dst_ops.gc_thresh = (rt_hash_mask + 1);
 34     ip_rt_max_size = (rt_hash_mask + 1) * 16;
 35 
 36     /*主要的初始化函数*/
 37     devinet_init();
 38     ip_fib_init();
 39 
 40     /* All the timers, started at system startup tend
 41        to synchronize. Perturb it a bit.
 42      */
 43     schedule_delayed_work(&expires_work,
 44         net_random() % ip_rt_gc_interval + ip_rt_gc_interval);
 45 
 46     if (register_pernet_subsys(&rt_secret_timer_ops))
 47         printk(KERN_ERR "Unable to setup rt_secret_timer\n");
 48 
 49     if (ip_rt_proc_init())
 50         printk(KERN_ERR "Unable to create route proc files\n");
 51 #ifdef CONFIG_XFRM
 52     xfrm_init();
 53     xfrm4_init();
 54 #endif
 55     /*注册rtnetlink 消息， 这里是获取路由， 在devinet_init()中还有其他三种消息*/
 56     rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL);
 57 
 58 #ifdef CONFIG_SYSCTL
 59     register_pernet_subsys(&sysctl_route_ops);
 60 #endif
 61     return rc;
 62 }
 63 
 64 /*
 65  * allocate a large system hash table from bootmem
 66  * - it is assumed that the hash table must contain an exact power-of-2
 67  *   quantity of entries(假定哈希表包含2的指数级的表项)
 68  * - limit is the number of hash buckets, not the total allocation size
 69  *   (limit 是哈希桶的数量， 不是所分配的整个空间的大小)
 70  */
 71 void *__init alloc_large_system_hash(const char *tablename,
 72                      unsigned long bucketsize,
 73                      unsigned long numentries,
 74                      int scale,
 75                      int flags,
 76                      unsigned int *_hash_shift,
 77                      unsigned int *_hash_mask,
 78                      unsigned long limit)
 79 
 80 void __init devinet_init(void)
 81 {
 82     /*还是初始struct net结构中的部分变量*/
 83     register_pernet_subsys(&devinet_ops);
 84 
 85     register_gifconf(PF_INET, inet_gifconf);
 86     /*注册一个通知链，主要处理设备的状态改变*/
 87     register_netdevice_notifier(&ip_netdev_notifier);
 88 
 89     /*另外的两个消息*/
 90     rtnl_register(PF_INET, RTM_NEWADDR, inet_rtm_newaddr, NULL);
 91     rtnl_register(PF_INET, RTM_DELADDR, inet_rtm_deladdr, NULL);
 92     rtnl_register(PF_INET, RTM_GETADDR, NULL, inet_dump_ifaddr);
 93 }
 94 
 95 这是ip_netdev_notifier的初始化值：
 96 static struct notifier_block ip_netdev_notifier = {
 97     .notifier_call = inetdev_event,
 98 };
 99 
100 ip_fib_init()在上一篇中已经介绍过！
posted on 2017-05-12 16:57 listenerln 阅读(619) 评论(0) 收藏举报
路由2 【转载: 再议路由初始化 】

路由2 【转载: 再议路由初始化】
