How to understand the macro __init?

* How to understand the macro __init?
@ 2012-08-14  2:14 王哲
  2012-08-14  4:04 ` Mulyadi Santosa
  0 siblings, 1 reply; 17+ messages in thread
From: 王哲 @ 2012-08-14  2:14 UTC (permalink / raw)
  To: kernelnewbies

 hi all

        in the kernel modules,we often use the macro __init.
if we only discuss the __init for functions.__init tells the
compiler to put  the function in a special section.and the
function are used once.So the code of this function should
be freed from the memory after the first call.

so i write a sample module:

#include <linux/module.h>
#include <linux/init.h>

void __init print_k(void)
{
    int k = 9;
    printk("<0>k = %d\n",k);
}

static int __init hello_init(void)
{
    printk("<0>hello kernel!\n");
    print_k();
    print_k();
    return 0;
}

static void __exit hello_exit(void)
{
    printk("<0>bye kernel!\n");
}

module_init(hello_init);
module_exit(hello_exit);
MODULE_LICENSE("GPL");

i use the __init for function print_k.
in my opinion  after the fisrt invoking the print_k in the hello_init.
the memory of print_k will be freed,and the second invoking will
not be executed.but the result of second invoking is executing .

why?

Thanks in advance!
wanny
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