Kernel 程式裡的命名規則
===
###### tags: `twlkh`, `naming`

# Kernel naming convention
找到幾篇關於 kernel 裡的命名規則，關於 `__` 開頭的函數與 `sys_` 與 `do_` 之間的關係。總結如下：

## `__` 開頭的函數

原本的函數在確認完輸入沒有問題[2]、處理完 lock 之後[1]，由 `__` 開頭的函數提供真正的實作。

~~~
In internal code, the convention usually is that
symbol __something is workhorse for something
excluding some management, often locking. That is
a reason for things like __d_lookup .
~~~

## `sys_` 與 `do_`
`sys_` 作為 syscall 的 C 的起始進入點，做完一些參數檢查後，真正的實作為 `do_` 開頭的函數。[3]

~~~
Functions implementing system calls under Linux
are prefixed with sys_, but they are usually
concerned only with argument checking or
arch-specific ways to pass some information
and the actual work is done by do_ functions.
~~~
# Reference
1. [What is the meaning of leading and trailing underscores in Linux kernel identifiers?](http://stackoverflow.com/questions/9432111/what-is-the-meaning-of-leading-and-trailing-underscores-in-linux-kernel-identifi)
2. [Re: double underscores](http://www.spinics.net/lists/newbies/msg02920.html)
3. [Linux Kernel 2.4 Internal: section 2.2](http://www.tldp.org/LDP/lki/lki-2.html)