数据交换sysctl + 定时器（code）

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

#include <linux/sysctl.h>
#include <linux/timer.h>

int value;

static struct ctl_table debug_table[] = {
	{
		.ctl_name       = CTL_UNNUMBERED,
		.procname       = "value",
		.data           = &value,
		.maxlen         = sizeof(value),
		.mode           = 0644,
		.proc_handler   = &proc_dointvec, },
	{ },
};

static struct ctl_table ws_dir_table[] = {
	{
		.ctl_name       = CTL_UNNUMBERED,
		.procname        = "debug",
		.mode            = 0555,
		.child           = debug_table, },
	{ },
};

static struct ctl_table ipv4_dir_table[] = {
	{
		.ctl_name       = NET_IPV4,
		.procname    = "ipv4",
		.mode        = 0555,
		.child       = ws_dir_table, },
	{ },
};

static ctl_table net_dir_table[] = {
	{
		.ctl_name       = CTL_NET,
		.procname    = "net",
		.mode        = 0555,
		.child           = ipv4_dir_table, },
	{ },
};

struct timer_list timer_last_stat;
static void output_value(unsigned long data)
{
	printk("value = %d\n", value);
	mod_timer(&timer_last_stat, jiffies+HZ*5);
}

struct ctl_table_header *ctl_header = NULL;
static int __init file_test_init(void)
{
	printk("sysctl test init\n");
	value = 111;
	ctl_header= register_sysctl_table (net_dir_table, 0);
	if(!ctl_header){
		printk(KERN_ERR"SYNPROXY: sp_sysctl_init() calls failed.");
		return -1;
	}
	setup_timer(&timer_last_stat, output_value, 0);
	mod_timer(&timer_last_stat, jiffies+HZ*5);
	return 0;
}

static void __exit file_test_exit(void)
{
	if (ctl_header)
		unregister_sysctl_table(ctl_header);
	del_timer(&timer_last_stat);
	printk("sysctl test exit\n");
}

module_init(file_test_init);
module_exit(file_test_exit);

MODULE_LICENSE("GPL");

$ dmesg
...
value = 111
$ echo 123 > /proc/sys/net/ipv4/debug/value
$ dmesg
...
value = 111
value = 123