Data Structure

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1019 static const struct net_proto_family inet_family_ops = {
1020         .family = PF_INET,
1021         .create = inet_create,
1022         .owner  = THIS_MODULE,
1023 };

call trace

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> inet_create
> > search the right inetsw array element with type/protocol
> > sock->ops = answer->ops;
> > k = sk_alloc(net, PF_INET, GFP_KERNEL, answer_prot);
> > sock_init_data(sock, sk);
> > init the sk

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Summary

System call socket will do two things:

1. create a struct socket *sock.
   Mainly done by __sock_create, which alloc a struct socket *sock,
   then init it with the creating method of net_families[family].
2. map the sock to a file descriptor by sock_map_fd.
   TODO…..

call trace:

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> socket
> > sock_create
> > > __sock_create
> > > > sock = sock_alloc();
> > > > sock->type = type;
> > > > rcu_read_lock();
> > > > pf = rcu_dereference(net_families[family]);
> > > > try_module_get(pf->owner))
> > > > rcu_read_unlock();
> > > > pf->create(net, sock, protocol, kern);
> > > > module_put(pf->owner)
> > socket_map_fd

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summary

Each family has a corresponding array element of struct net_proto_family,
which will be called in system call socket.

Data Structure

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181 struct net_proto_family {
182         int             family;
183         int             (*create)(struct net *net, struct socket *sock,
184                                   int protocol, int kern);
185         struct module   *owner;
186 };

The create is important, which is first and basic function during
system call socket.

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164 static DEFINE_SPINLOCK(net_family_lock);
165 static const struct net_proto_family __rcu *net_families[NPROTO] __read_mostly;

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Requirement

I want to write blog with github page and octopress in the office
and in the home.

Steps

The github page has work well done with pc in the home.
Now setup the environment in office to write github page.
The github page repo:
https://github.com/martinbj2008/martinbj2008.github.io

the octopress is pushed to git repo as branch “source”

How to write blog and sync them to github while avoid conflict with home?

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calltrace

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> ip_rcv_finish
> > ip_route_input_noref
> > > ip_route_input_slow
> > > > fib_lookup
> > > > > fib_table_lookup with RT_TABLE_LOCAL
> > > > > fib_table_lookup with RT_TABLE_MAIN
> > > > ip_mkroute_input

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On ubuntu 13.04, create the file ~/.config/gtk-3.0/gtk.css with following lines

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martin@ubuntu:~$ cat ~/.config/gtk-3.0/gtk.css 
TerminalWindow .notebook tab:active {
    background-color: #0000FF;	
    }
martin@ubuntu:~$ 

summary

inflate duplicate a new node whose child array is double of orignal node,
and put original node’s child into the new node.

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call trace

以插入一条新的路由为例。

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> fib_insert_node
> > trie_rebalance
> > > while loop
> > > > resize
> > > > tnode_put_child_reorg
> > > > tnode_free_flush

trie_rebalance

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for_each_node(from current node tn to  fib_trie root)
	call resize()
	tnode_put_child_reorg

从当前节点开始一直到根节点，以当前节点作为一个子树，
反复调用resize, 并通过tnode_put_child_reorg
更新当前节点的父节点的统计信息。

注： resize可能会更改子树的根节点！

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summary

softirq 真正干活的函数是__do_softirq。
linuxv3.11内核里能够执行__do_softirq,有如下调用,
这里指真正执行softirq的地方，不是触发(设置)softirq标志 !!!

1. 每个硬中断退出的时。
2. 当bh使能的时。
3. 发送回环报文时。

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steps

step 1. 循环fib_trie, 直到当前节点为空或者是叶子节点时，停止。
1.a
比较当前节点的key跟待插入的key的前pos位,
如果不相等，循环结束。如果相等执行1.b
（作为改进，加上父节点已经比较了前posx位， 那么只需比较
(posx，pos)这区间的位即可。 注意posx有可能与pos相等。
1.b
记录已经比较的位数(tn->pos + tn->bits)
取当前节点的一个孩子节点，
tkey_extract_bits(key, tn->pos, tn->bits)
继续执行。

step 2. 循环结束，当前节点n有可能为空，也有可能是个叶子节点,或者中间节点(1.a).

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if (n == NULL)
	if (fib_trie == NULL)
		shit! 树的第一个节点。
	else
		当前节点是父节点的一个空孩子节点。
		以为树不是空的，所以父节点肯定存在。
		见 case2
else n is a leaf 
	if (tkey_equals(key, n->key)) //'key'值相同
		case 1:
		路由前缀相同（可能掩码不一样)
	else
		case 3b.
else
	//assert n is a internal node
	并且，当前节点的key的pos位跟待插入的key的前pos位不相等。
	见case3a

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