workqueue sample on linux kernel

sample.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/workqueue.h>

static void mykmod_work_handler(struct work_struct *w);

static struct workqueue_struct *wq = 0;
static DECLARE_DELAYED_WORK(mykmod_work, mykmod_work_handler);
static unsigned long onesec;

static void
mykmod_work_handler(struct work_struct *w)
{
        pr_info("mykmod work %u jiffies\n", (unsigned)onesec);
}


static int __devinit mykmod_init(void)
{
        onesec = msecs_to_jiffies(1000);
        pr_info("mykmod loaded %u jiffies\n", (unsigned)onesec);

        if (!wq)
                wq = create_singlethread_workqueue("mykmod");
        if (wq)
                queue_delayed_work(wq, &mykmod_work, onesec);

        return 0;
}

static void __devexit mykmod_exit(void)
{
        if (wq)
                destroy_workqueue(wq);
        pr_info("mykmod exit\n");
}

module_init(mykmod_init);
module_exit(mykmod_exit);

MODULE_DESCRIPTION("mykmod");
MODULE_LICENSE("GPL");

Don't forget to cancel the possible work in the queue (cancel_delayed_work_sync) when you close the workqueue, otherwise your kernel will crash.

You are a lifesaver, arxchruncher, I had spent an hour trying to figure out why my kernel crashed.

Here is a minimal working example using cancel_work_sync https://github.com/cirosantilli/linux-kernel-module-cheat/blob/ad077d3943f79c0f6481dab929970613c33c31a7/kernel_module/workqueue_cheat.c

Great work! @cirosantilli