Linux workqueue 实例分析

先贴代码，稍后分析

 

/*
 * work_queue.c: [e-mail]
 * 2009-01-03
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>

#include <linux/time.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <asm/atomic.h>


MODULE_AUTHOR("dreamice");
MODULE_LICENSE("Dual BSD/GPL");

struct timer_data {
        struct timer_list timer;
        struct workqueue_struct *work_queue;
        unsigned long prev_jiffies;
        unsigned int loops;
};

struct timer_data test_data;
struct timer_data test_data1;

static void do_work(void *);
static DECLARE_WORK(test_work, do_work, NULL);

static DECLARE_WORK(test_work1, do_work, NULL);

static struct workqueue_struct *test_workqueue;

atomic_t wq_run_times;
unsigned int failed_cnt = 0;

static int work_delay = 2 * HZ; /* timer interval */

void test_timer_fn(unsigned long arg)
{
        struct timer_data *data = (struct timer_data *)arg;
        unsigned long j = jiffies;
        data->timer.expires += work_delay;
        data->prev_jiffies = j;
        add_timer(&data->timer);
        if (queue_work(test_workqueue, &test_work) == 0) {
                printk("Timer (0) add work queue failed\n");
                (*(&failed_cnt))++;
        }
        data->loops++;
        printk("timer-0 loops: %u\n", data->loops);
}
void test_timer_fn1(unsigned long arg)
{
        struct timer_data *data = (struct timer_data *)arg;
        unsigned long j = jiffies;
        data->timer.expires += 3 * HZ;
        data->prev_jiffies = j;
        add_timer(&data->timer);
        //if (queue_work(test_workqueue, &test_work) == 0) {

        if (queue_work(test_workqueue, &test_work1) == 0) {
                printk("Timer (1) add work queue failed\n");
                (*(&failed_cnt))++;
        }
        data->loops++;
        printk("timer-1 loops: %u\n", data->loops);
}

void do_work(void *arg)
{
        atomic_inc(&wq_run_times);
        printk("====work queue run times: %u====\n", atomic_read(&wq_run_times));
        printk("====failed count: %u====\n", *(&failed_cnt));
}

int wq_init(void)
{
        unsigned long j = jiffies;
        printk("jiffies: %lu\n", jiffies);
        atomic_set(&wq_run_times, 0);

        init_timer(&test_data.timer);
        test_data.loops = 0;
       test_data.prev_jiffies = j;
        test_data.timer.function = test_timer_fn;
        test_data.timer.data = (unsigned long)(&test_data);
        test_data.timer.expires = j + 2 * HZ;
        add_timer(&test_data.timer);

        init_timer(&test_data1.timer);
        test_data1.loops = 0;
        test_data1.prev_jiffies = j;
        test_data1.timer.function = test_timer_fn1;
        test_data1.timer.data = (unsigned long)(&test_data1);
        test_data1.timer.expires = j + 3 * HZ;
        add_timer(&test_data1.timer);

        test_workqueue = create_singlethread_workqueue("test-wq");

        printk("test-wq init success\n");
        printk("jiffies: %lu\n", jiffies);
        return 0;
}
void wq_exit(void)
{
        del_timer(&test_data.timer);
        del_timer(&test_data1.timer);
        destroy_workqueue(test_workqueue);
        printk("wq exit success\n");
}
module_init(wq_init);
module_exit(wq_exit)


 

本文通过内核定时器来触发工作队列工作。除了工作队列的函数接口以外，我们还必须注意，如果一个函数已经在工作队列中了，那么，当再次添加该调用函数到同一工作队列中时，将失败。这也是本文测试注释掉的部分，测试时会显示添加失败。