/***********************************************************************/

//完成接口

//内核中的许多部分初始化某些活动为单独的执行线程，然后等待这些线程完成。

//完成接口是一种有效并简单的方式来实现这样的代码模式。

/***********************************************************************/

#include<linux/completion.h>

#include<linux/module.h>

#include<linux/sched.h>

#include<linux/init.h>

staticDECLARE_COMPLETION(my_thread_exit); /* Completion */

staticDECLARE_WAIT_QUEUE_HEAD(my_thread_wait); /* Wait Queue */

intpink_slip = 0; /* Exit Flag */

/*Helper thread */

staticint

my_thread(void*unused)

{

DECLARE_WAITQUEUE(wait,current);

daemonize("my_thread");

add_wait_queue(&my_thread_wait,&wait);

while(1) {

/*Relinquish processor until event occurs */

set_current_state(TASK_INTERRUPTIBLE);

schedule();

/*Control gets here when the thread is woken

upfrom the my_thread_wait wait queue */

/*Quit if let go */

if(pink_slip) {

break;

}

/*Do the real work */

/*... */

}

/*Bail out of the wait queue */

__set_current_state(TASK_RUNNING);

remove_wait_queue(&my_thread_wait,&wait);

/*Atomically signal completion and exit */

complete_and_exit(&my_thread_exit,0);

}

/*Module Initialization */

staticint __init

my_init(void)

{

/*... */

/*Kick start the thread */

kernel_thread(my_thread,NULL,

CLONE_FS| CLONE_FILES | CLONE_SIGHAND | SIGCHLD);

/*... */

return0;

}

/*Module Release */

staticvoid __exit

my_release(void)

{

/*... */

pink_slip= 1; /* my_thread must go */

wake_up(&my_thread_wait); /* Activate my_thread */

wait_for_completion(&my_thread_exit);/* Wait until my_thread

quits */

/*... */

}

module_init(my_init);

module_exit(my_release);