想來都有點恨自己，前幾個月遇到的＂難題＂．還是沒有解決．一直卡死，又找不出原因．

吐個槽，那些只貼程式碼不附上執行結果的toturial，　我表示．．．我就不明白，既然有些bloger程式碼都給出來了

讓我這種渣渣看一下腫麼用的會怎麼樣？看一下你執行結果會怎麼樣？

說明：額．．．這個問題＂貼＂沒有附上執行結果，是因為直接會卡死我的Linux主機，然後我壓根沒辦法截圖給大家看，也沒辦法debug.　希望諒解

－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－

問題程式碼一:

/***********************************************************
code writer	: EOF
code date	: 2014.09.02
code file	: proc_time_delay.c
e-mail		: 
 
[email protected]

code purpose:
	
	This code is programmed for how to delay 1 second by 
jiffies and HZ.

	If there is something wrong with my code, please touch
me by e-mail. Thank you.

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

#include <linux/fs.h>
#include <linux/proc_fs.h>	/* for procfs */
#include <linux/seq_file.h>	/* for 'struct seq_file' */
#include <linux/types.h>

#include <linux/jiffies.h>	/* for jiffies */

#define PROC_NAME "delay_one_second"

MODULE_AUTHOR("Jason Leaster");
MODULE_LICENSE("Dual BSD/GPL");

static int proc_demo_seq_show(struct seq_file* sfile,void* v)
{
	int tmp = 0;

	unsigned long jif = jiffies;
	unsigned long one_second_later = jiffies + HZ;

	for(tmp = 0; tmp < 10;tmp++)
	{
		while(time_after(one_second_later,jif))
		{
			jif = jiffies;
		}		
		one_second_later = jif + HZ;
		seq_printf(sfile,"Hello world! jiffies:%lu\n",jif);
	}

	return 0;
}

static void* proc_demo_seq_start(struct seq_file* sfile,loff_t *pos)
{
	return NULL;
}

static void proc_demo_seq_stop(struct seq_file* sfile,void* v)
{
	/* Nothing to be done. */
}

static void* proc_demo_seq_next(struct seq_file* sfile,void* v,loff_t* pos)
{
	return NULL;
}

static struct seq_operations proc_demo_ops = 
{
	.start	=	proc_demo_seq_start,
	.next	=	proc_demo_seq_next,
	.stop	=	proc_demo_seq_stop,
	.show	=	proc_demo_seq_show,
};

static int proc_demo_open(struct inode* inode, struct file* filp)
{
	return single_open(filp,&proc_demo_seq_show,NULL);
}

struct file_operations proc_demo_fops = 
{
	.owner	=	THIS_MODULE,
	.open	=	proc_demo_open,
	.read	=	seq_read,
	.release=	seq_release,
};

int proc_demo_init(void)
{
	struct proc_dir_entry * entry = NULL;
	
	entry =	proc_create(PROC_NAME,0,NULL,&proc_demo_fops);
	if(!entry)
	{
		printk(KERN_ALERT "line:%d proc_create failed!",__LINE__);
	}

	return 0;
}

void proc_demo_exit(void)
{
	/*
	**       The second parameter of 'remove_proc_entry()' is 
	** a pointer which point to parent directory.We create our
	** proc-entry-point in /proc/, so we pass NULL into it.
	*/
	remove_proc_entry(PROC_NAME,NULL);
}

module_init(proc_demo_init);
module_exit(proc_demo_exit);
 

/***********************************************************
code writer	: EOF
code date	: 2014.09.02
code file	: proc_time_delay.c
e-mail		: [email protected]

code purpose:
	
	This code is programmed for how to delay by kernel
timer.

	If there is something wrong with my code, please touch
me by e-mail. Thank you.

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

#include <linux/fs.h>
#include <linux/proc_fs.h>	/* for procfs */
#include <linux/seq_file.h>	/* for 'struct seq_file' */
#include <linux/types.h>

#include <linux/jiffies.h>	/* for jiffies */
#include <linux/timer.h>	/* for timer*/

#include <linux/sched.h>
#include <linux/slab.h>

#define PROC_NAME "delay_kernel_timer"

MODULE_AUTHOR("Jason Leaster");
MODULE_LICENSE("Dual BSD/GPL");

#define LOOP 5

/*
**	First of all, you should make abstract a model
** for our device driver and include the timer.
*/

struct timer_delay_model
{
	struct timer_list timer;
	wait_queue_head_t wait;
	unsigned long prevjiffies;
	struct seq_file	* output;

	int loops ;
	/*	...	*/
};

void jif_timer_fn(unsigned long arg)
{
	struct timer_delay_model* p_model = (struct timer_delay_model*)arg;
	unsigned long jif = jiffies;

	seq_printf(p_model->output,"Hello world! jiffies:%lu\n",jif);

	printk(KERN_ALERT "in jif_timer_fc %d\n",p_model->loops);

/*
	if(--(p_model->loops))
	{
		p_model->timer.expires += HZ;
		p_model->prevjiffies	= jif;

		add_timer(&p_model->timer);
	}
	else
	{
		wake_up_interruptible(&p_model->wait);
	}
*/

	p_model->loops = 0;
}

static int proc_demo_seq_show(struct seq_file* sfile,void* v)
{
	unsigned long jif = jiffies;

	struct timer_delay_model* p_model;

	p_model = kmalloc(sizeof(struct timer_delay_model),GFP_KERNEL);

	if(!p_model)
	{
		printk(KERN_ALERT "kmalloc error in %d %s\n",__LINE__,__FUNCTION__);
		return -ENOMEM;
	}
	else
	{
		printk(KERN_ALERT "start to initialization %lu\n",jiffies);
		init_timer(&p_model->timer);
		init_waitqueue_head(&p_model->wait);
	
		p_model->prevjiffies	= jif;
		p_model->output		= sfile;
		p_model->loops		= LOOP;
		p_model->timer.data	= (unsigned long) sfile;
		p_model->timer.function = jif_timer_fn;
		p_model->timer.expires	= jif + HZ;// delay 1 second
		printk(KERN_ALERT "add_timer  ing %lu\n",jiffies);
		add_timer(&p_model->timer);
	}

	printk(KERN_ALERT "add_timer  finished %lu\n",jiffies);

//	wait_event_interruptible(p_model->wait,!(p_model->loops));

	while(time_after(p_model->prevjiffies + HZ,jif))
	{
		jif = jiffies;
	}		

	printk(KERN_ALERT "wait finished\n");

	kfree(p_model);

	if (signal_pending(current))
		return -ERESTARTSYS;

	return 0;
}

static void* proc_demo_seq_start(struct seq_file* sfile,loff_t *pos)
{
	return NULL;
}

static void proc_demo_seq_stop(struct seq_file* sfile,void* v)
{
	/* Nothing to be done. */
}

static void* proc_demo_seq_next(struct seq_file* sfile,void* v,loff_t* pos)
{
	return NULL;
}

static struct seq_operations proc_demo_ops = 
{
	.start	=	proc_demo_seq_start,
	.next	=	proc_demo_seq_next,
	.stop	=	proc_demo_seq_stop,
	.show	=	proc_demo_seq_show,
};

static int proc_demo_open(struct inode* inode, struct file* filp)
{
	return single_open(filp,&proc_demo_seq_show,NULL);
}

struct file_operations proc_demo_fops = 
{
	.owner	=	THIS_MODULE,
	.open	=	proc_demo_open,
	.read	=	seq_read,
	.release=	single_release,
};

int proc_demo_init(void)
{
	struct proc_dir_entry * entry = NULL;
	
	entry =	proc_create(PROC_NAME,0,NULL,&proc_demo_fops);
	if(!entry)
	{
		printk(KERN_ALERT "line:%d proc_create failed!",__LINE__);
	}

	return 0;
}

void proc_demo_exit(void)
{
	/*
	**       The second parameter of 'remove_proc_entry()' is 
	** a pointer which point to parent directory.We create our
	** proc-entry-point in /proc/, so we pass NULL into it.
	*/
	remove_proc_entry(PROC_NAME,NULL);
}

module_init(proc_demo_init);
module_exit(proc_demo_exit);