Use a variable before it's declaration

[Bjørn Mork]

Rock Lee <rocklee_104 at outlook.com> writes:

> Hi, all:
> 	Here is a snippet of linux-v3.4 which drives me crazy.
> Because init_task hasn't been declared yet when init_thread_union is 
> initializing. Why is there no compiling error? Any hint would be helpful.
>
> union thread_union init_thread_union __init_task_data = 
>
>      { INIT_THREAD_INFO(init_task) }; 
>
>  
>
> /* 
>
>   * Initial task structure. 
>
>   * 
>
>   * All other task structs will be allocated on slabs in fork.c 
>
>   */ 
>
> struct task_struct init_task = INIT_TASK(init_task);


Because init_task is declared "extern" in linux/sched.h


Bjørn