内核开发0 --- 代码规范

注释

使用/* */ 不要使用//

宏

宏定义需要大写，函数宏可以小写

typedef

不要对结构体和指针使用typedef

Please don't use things like ``vps_t``.
It's a **mistake** to use typedef for structures and pointers. When you see a

.. code-block:: c


	vps_t a;

in the source, what does it mean?
In contrast, if it says

.. code-block:: c

	struct virtual_container *a;

you can actually tell what ``a`` is.

Lots of people think that typedefs ``help readability``. Not so. They are
useful only for:

 (a) totally opaque objects (where the typedef is actively used to **hide**
     what the object is).

     Example: ``pte_t`` etc. opaque objects that you can only access using
     the proper accessor functions.

     .. note::

       Opaqueness and ``accessor functions`` are not good in themselves.
       The reason we have them for things like pte_t etc. is that there
       really is absolutely **zero** portably accessible information there.

 (b) Clear integer types, where the abstraction **helps** avoid confusion
     whether it is ``int`` or ``long``.

     u8/u16/u32 are perfectly fine typedefs, although they fit into
     category (d) better than here.

     .. note::

       Again - there needs to be a **reason** for this. If something is
       ``unsigned long``, then there's no reason to do

	typedef unsigned long myflags_t;

     but if there is a clear reason for why it under certain circumstances
     might be an ``unsigned int`` and under other configurations might be
     ``unsigned long``, then by all means go ahead and use a typedef.

 (c) when you use sparse to literally create a **new** type for
     type-checking.

 (d) New types which are identical to standard C99 types, in certain
     exceptional circumstances.

     Although it would only take a short amount of time for the eyes and
     brain to become accustomed to the standard types like ``uint32_t``,
     some people object to their use anyway.

     Therefore, the Linux-specific ``u8/u16/u32/u64`` types and their
     signed equivalents which are identical to standard types are
     permitted -- although they are not mandatory in new code of your
     own.

     When editing existing code which already uses one or the other set
     of types, you should conform to the existing choices in that code.

 (e) Types safe for use in userspace.

     In certain structures which are visible to userspace, we cannot
     require C99 types and cannot use the ``u32`` form above. Thus, we
     use __u32 and similar types in all structures which are shared
     with userspace.

Maybe there are other cases too, but the rule should basically be to NEVER
EVER use a typedef unless you can clearly match one of those rules.

In general, a pointer, or a struct that has elements that can reasonably
be directly accessed should **never** be a typedef.
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控制访问性

不被导出的函数和变量必须声明为静态的