/* vim: set ts=4: *//* * Copywrite 2002 Der Herr Hofrat * License GPL V2 * Author der.herr@hofr.at *//* * sample sysctl usage  */ #include <linux/module.h> /* module macros etc. */#include <linux/version.h>#include <linux/kernel.h> /* printk levels */#ifndef CONFIG_SYSCTL	#error "Need CONFIG_SYSCTL set to build this sample properly"	#ifndef CONFIG_PROC_FS		#error "Need CONFIG_PROC_FS to build this sample properly"	#endif /* CONFIG_PROC_FS */#endif /* CONFIG_SYSCTL */#include <linux/sysctl.h> /* sysctl stuff */#include <linux/fs.h> /* filp */static void simple_sysctl_register(void);enum {	DEV_SIMPLE_INFO=1,	DEV_SIMPLE_DEBUG=2};MODULE_LICENSE("GPL v2");MODULE_AUTHOR("Der Herr Hofrat <der.herr@hofr.at>");MODULE_DESCRIPTION("sample usage of sysctl functions");#define INFO_STR_SIZE 1024static int debug;struct simple_sysctl_settings {	char	info[INFO_STR_SIZE];	/* general info */	int	debug;			/* debug level */} simple_sysctl_settings;int simple_sysctl_info(ctl_table *ctl, 	int write, 	struct file * filp,	void *buffer, 	size_t *lenp){	int pos;	char *msg = simple_sysctl_settings.info;		if (!*lenp || (filp->f_pos && !write))	{		*lenp = 0;		return 0;	}	pos = sprintf(msg, "Some infos via sysctl");	return proc_dostring(ctl, write, filp, buffer, lenp);}/* This "handler" should take care of all sysctl cases you might need  * thats why we have this seemingly useless switch in here  */static int simple_sysctl_handler(ctl_table *ctl, 	int write, 	struct file * filp,	void *buffer, 	size_t *lenp){	int *valp = ctl->data;	int val = *valp;	int ret;	/* grab data if it is int */		ret = proc_dointvec(ctl, write, filp, buffer, lenp);	/* sanity check - is this write ? did we get anything ? */	if (write && *valp != val) {		printk("received %d",*valp);			/* sanity check - only want 1 or 0. */		if (*valp)			*valp = 1;		else			*valp = 0;		switch (ctl->ctl_name) {			case DEV_SIMPLE_DEBUG: {				if (valp == &simple_sysctl_settings.debug)					debug = simple_sysctl_settings.debug;				break;			}		}		printk(" - setting debug to %d\n",*valp);	} /* nothing to do if we are not called in write mode */	return ret;}/* files go in /proc/sys/dev/simple as "info" "debug" etc. */ctl_table simple_table[] = {	{DEV_SIMPLE_INFO, "info", &simple_sysctl_settings.info, 		INFO_STR_SIZE, 0444, NULL, &simple_sysctl_info},	{DEV_SIMPLE_DEBUG, "debug", &simple_sysctl_settings.debug, 		sizeof(int), 0644, NULL, &simple_sysctl_handler},	{0}};/* setup a simple subdir */ctl_table simple_simple_table[] = {	{DEV_SIMPLE_INFO, "simple", NULL, 0, 0555, simple_table},	{0}};/* Make sure that /proc/sys/dev is setup */ctl_table simple_root_table[] = {	{CTL_DEV, "dev", NULL, 0, 0555, simple_simple_table},	{0}};static struct ctl_table_header *simple_sysctl_header;static void simple_sysctl_register(void){	static int initialized;	if (initialized == 1)		return;	simple_sysctl_header = register_sysctl_table(simple_root_table, 1);	simple_sysctl_settings.debug = debug;	initialized = 1;}static void simple_sysctl_unregister(void){	if (simple_sysctl_header)		unregister_sysctl_table(simple_sysctl_header);}static int __init simple_dev_init(void){		simple_sysctl_register();		return 0;}static void __exit simple_dev_exit(void){	simple_sysctl_unregister();}module_init(simple_dev_init);module_exit(simple_dev_exit);