[mirror_ubuntu-bionic-kernel.git] / drivers / watchdog / softdog.c

/*
 *	SoftDog	0.07:	A Software Watchdog Device
 *
 *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
 *							All Rights Reserved.
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
 *	warranty for any of this software. This material is provided
 *	"AS-IS" and at no charge.
 *
 *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 *	Software only watchdog driver. Unlike its big brother the WDT501P
 *	driver this won't always recover a failed machine.
 *
 *  03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
 *	Modularised.
 *	Added soft_margin; use upon insmod to change the timer delay.
 *	NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
 *	    minors.
 *
 *  19980911 Alan Cox
 *	Made SMP safe for 2.3.x
 *
 *  20011127 Joel Becker (jlbec@evilplan.org>
 *	Added soft_noboot; Allows testing the softdog trigger without
 *	requiring a recompile.
 *	Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
 *
 *  20020530 Joel Becker <joel.becker@oracle.com>
 *	Added Matt Domsch's nowayout module option.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/uaccess.h>

#define PFX "SoftDog: "

#define TIMER_MARGIN	60		/* Default is 60 seconds */
static int soft_margin = TIMER_MARGIN;	/* in seconds */
module_param(soft_margin, int, 0);
MODULE_PARM_DESC(soft_margin,
	"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
					__MODULE_STRING(TIMER_MARGIN) ")");

static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout,
		"Watchdog cannot be stopped once started (default="
				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

#ifdef ONLY_TESTING
static int soft_noboot = 1;
#else
static int soft_noboot = 0;
#endif  /* ONLY_TESTING */

module_param(soft_noboot, int, 0);
MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");

/*
 *	Our timer
 */

static void watchdog_fire(unsigned long);

static struct timer_list watchdog_ticktock =
		TIMER_INITIALIZER(watchdog_fire, 0, 0);
static unsigned long driver_open, orphan_timer;
static char expect_close;


/*
 *	If the timer expires..
 */

static void watchdog_fire(unsigned long data)
{
	if (test_and_clear_bit(0, &orphan_timer))
		module_put(THIS_MODULE);

	if (soft_noboot)
		printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
	else {
		printk(KERN_CRIT PFX "Initiating system reboot.\n");
		emergency_restart();
		printk(KERN_CRIT PFX "Reboot didn't ?????\n");
	}
}

/*
 *	Softdog operations
 */

static int softdog_keepalive(void)
{
	mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
	return 0;
}

static int softdog_stop(void)
{
	del_timer(&watchdog_ticktock);
	return 0;
}

static int softdog_set_heartbeat(int t)
{
	if ((t < 0x0001) || (t > 0xFFFF))
		return -EINVAL;

	soft_margin = t;
	return 0;
}

/*
 *	/dev/watchdog handling
 */

static int softdog_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(0, &driver_open))
		return -EBUSY;
	if (!test_and_clear_bit(0, &orphan_timer))
		__module_get(THIS_MODULE);
	/*
	 *	Activate timer
	 */
	softdog_keepalive();
	return nonseekable_open(inode, file);
}

static int softdog_release(struct inode *inode, struct file *file)
{
	/*
	 *	Shut off the timer.
	 * 	Lock it in if it's a module and we set nowayout
	 */
	if (expect_close == 42) {
		softdog_stop();
		module_put(THIS_MODULE);
	} else {
		printk(KERN_CRIT PFX
			"Unexpected close, not stopping watchdog!\n");
		set_bit(0, &orphan_timer);
		softdog_keepalive();
	}
	clear_bit(0, &driver_open);
	expect_close = 0;
	return 0;
}

static ssize_t softdog_write(struct file *file, const char __user *data,
						size_t len, loff_t *ppos)
{
	/*
	 *	Refresh the timer.
	 */
	if (len) {
		if (!nowayout) {
			size_t i;

			/* In case it was set long ago */
			expect_close = 0;

			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					expect_close = 42;
			}
		}
		softdog_keepalive();
	}
	return len;
}

static long softdog_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	int new_margin;
	static const struct watchdog_info ident = {
		.options =		WDIOF_SETTIMEOUT |
					WDIOF_KEEPALIVEPING |
					WDIOF_MAGICCLOSE,
		.firmware_version =	0,
		.identity =		"Software Watchdog",
	};
	switch (cmd) {
	case WDIOC_GETSUPPORT:
		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		return put_user(0, p);
	case WDIOC_KEEPALIVE:
		softdog_keepalive();
		return 0;
	case WDIOC_SETTIMEOUT:
		if (get_user(new_margin, p))
			return -EFAULT;
		if (softdog_set_heartbeat(new_margin))
			return -EINVAL;
		softdog_keepalive();
		/* Fall */
	case WDIOC_GETTIMEOUT:
		return put_user(soft_margin, p);
	default:
		return -ENOTTY;
	}
}

/*
 *	Notifier for system down
 */

static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
	void *unused)
{
	if (code == SYS_DOWN || code == SYS_HALT)
		/* Turn the WDT off */
		softdog_stop();
	return NOTIFY_DONE;
}

/*
 *	Kernel Interfaces
 */

static const struct file_operations softdog_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= softdog_write,
	.unlocked_ioctl	= softdog_ioctl,
	.open		= softdog_open,
	.release	= softdog_release,
};

static struct miscdevice softdog_miscdev = {
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &softdog_fops,
};

static struct notifier_block softdog_notifier = {
	.notifier_call	= softdog_notify_sys,
};

static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";

static int __init watchdog_init(void)
{
	int ret;

	/* Check that the soft_margin value is within it's range;
	   if not reset to the default */
	if (softdog_set_heartbeat(soft_margin)) {
		softdog_set_heartbeat(TIMER_MARGIN);
		printk(KERN_INFO PFX
		    "soft_margin must be 0 < soft_margin < 65536, using %d\n",
			TIMER_MARGIN);
	}

	ret = register_reboot_notifier(&softdog_notifier);
	if (ret) {
		printk(KERN_ERR PFX
			"cannot register reboot notifier (err=%d)\n", ret);
		return ret;
	}

	ret = misc_register(&softdog_miscdev);
	if (ret) {
		printk(KERN_ERR PFX
			"cannot register miscdev on minor=%d (err=%d)\n",
						WATCHDOG_MINOR, ret);
		unregister_reboot_notifier(&softdog_notifier);
		return ret;
	}

	printk(banner, soft_noboot, soft_margin, nowayout);

	return 0;
}

static void __exit watchdog_exit(void)
{
	misc_deregister(&softdog_miscdev);
	unregister_reboot_notifier(&softdog_notifier);
}

module_init(watchdog_init);
module_exit(watchdog_exit);

MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("Software Watchdog Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* SoftDog 0.07: A Software Watchdog Device
	3	*
143a2e54 WVS	4	* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
143a2e54 WVS	5	* All Rights Reserved.
1da177e4 LT	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public License
	9	* as published by the Free Software Foundation; either version
	10	* 2 of the License, or (at your option) any later version.
	11	*
	12	* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
	13	* warranty for any of this software. This material is provided
	14	* "AS-IS" and at no charge.
	15	*
	16	* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
	17	*
	18	* Software only watchdog driver. Unlike its big brother the WDT501P
	19	* driver this won't always recover a failed machine.
	20	*
	21	* 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
	22	* Modularised.
	23	* Added soft_margin; use upon insmod to change the timer delay.
	24	* NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
	25	* minors.
	26	*
	27	* 19980911 Alan Cox
	28	* Made SMP safe for 2.3.x
	29	*
	30	* 20011127 Joel Becker (jlbec@evilplan.org>
	31	* Added soft_noboot; Allows testing the softdog trigger without
	32	* requiring a recompile.
	33	* Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
	34	*
	35	* 20020530 Joel Becker <joel.becker@oracle.com>
143a2e54	36	* Added Matt Domsch's nowayout module option.
1da177e4 LT	37	*/
	38
	39	#include <linux/module.h>
	40	#include <linux/moduleparam.h>
1da177e4 LT	41	#include <linux/types.h>
	42	#include <linux/timer.h>
	43	#include <linux/miscdevice.h>
	44	#include <linux/watchdog.h>
	45	#include <linux/fs.h>
	46	#include <linux/notifier.h>
	47	#include <linux/reboot.h>
	48	#include <linux/init.h>
4e57b681	49	#include <linux/jiffies.h>
f92d3749	50	#include <linux/uaccess.h>
1da177e4 LT	51
	52	#define PFX "SoftDog: "
	53
	54	#define TIMER_MARGIN 60 /* Default is 60 seconds */
	55	static int soft_margin = TIMER_MARGIN; /* in seconds */
	56	module_param(soft_margin, int, 0);
f92d3749 AC	57	MODULE_PARM_DESC(soft_margin,
	58	"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
	59	__MODULE_STRING(TIMER_MARGIN) ")");
1da177e4	60
4bfdf378	61	static int nowayout = WATCHDOG_NOWAYOUT;
1da177e4	62	module_param(nowayout, int, 0);
f92d3749 AC	63	MODULE_PARM_DESC(nowayout,
	64	"Watchdog cannot be stopped once started (default="
	65	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
1da177e4 LT	66
	67	#ifdef ONLY_TESTING
	68	static int soft_noboot = 1;
	69	#else
	70	static int soft_noboot = 0;
	71	#endif /* ONLY_TESTING */
	72
	73	module_param(soft_noboot, int, 0);
	74	MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
	75
	76	/*
	77	* Our timer
	78	*/
	79
	80	static void watchdog_fire(unsigned long);
	81
	82	static struct timer_list watchdog_ticktock =
	83	TIMER_INITIALIZER(watchdog_fire, 0, 0);
1cc77248	84	static unsigned long driver_open, orphan_timer;
1da177e4 LT	85	static char expect_close;
	86
	87
	88	/*
	89	* If the timer expires..
	90	*/
	91
	92	static void watchdog_fire(unsigned long data)
	93	{
1cc77248 CE	94	if (test_and_clear_bit(0, &orphan_timer))
	95	module_put(THIS_MODULE);
	96
1da177e4 LT	97	if (soft_noboot)
1da177e4 LT	98	printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
f92d3749	99	else {
1da177e4	100	printk(KERN_CRIT PFX "Initiating system reboot.\n");
479d0f41	101	emergency_restart();
1da177e4 LT	102	printk(KERN_CRIT PFX "Reboot didn't ?????\n");
	103	}
	104	}
	105
	106	/*
	107	* Softdog operations
	108	*/
	109
	110	static int softdog_keepalive(void)
	111	{
	112	mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
	113	return 0;
	114	}
	115
	116	static int softdog_stop(void)
	117	{
	118	del_timer(&watchdog_ticktock);
	119	return 0;
	120	}
	121
	122	static int softdog_set_heartbeat(int t)
	123	{
	124	if ((t < 0x0001) \|\| (t > 0xFFFF))
	125	return -EINVAL;
	126
	127	soft_margin = t;
	128	return 0;
	129	}
	130
	131	/*
	132	* /dev/watchdog handling
	133	*/
	134
	135	static int softdog_open(struct inode inode, struct file file)
	136	{
1cc77248	137	if (test_and_set_bit(0, &driver_open))
1da177e4	138	return -EBUSY;
1cc77248	139	if (!test_and_clear_bit(0, &orphan_timer))
1da177e4 LT	140	__module_get(THIS_MODULE);
	141	/*
	142	* Activate timer
	143	*/
	144	softdog_keepalive();
	145	return nonseekable_open(inode, file);
	146	}
	147
	148	static int softdog_release(struct inode inode, struct file file)
	149	{
	150	/*
	151	* Shut off the timer.
	152	* Lock it in if it's a module and we set nowayout
	153	*/
	154	if (expect_close == 42) {
	155	softdog_stop();
1cc77248	156	module_put(THIS_MODULE);
1da177e4	157	} else {
f92d3749 AC	158	printk(KERN_CRIT PFX
f92d3749 AC	159	"Unexpected close, not stopping watchdog!\n");
1cc77248	160	set_bit(0, &orphan_timer);
1da177e4 LT	161	softdog_keepalive();
1da177e4 LT	162	}
1cc77248	163	clear_bit(0, &driver_open);
1da177e4 LT	164	expect_close = 0;
	165	return 0;
	166	}
	167
f92d3749 AC	168	static ssize_t softdog_write(struct file file, const char __user data,
f92d3749 AC	169	size_t len, loff_t *ppos)
1da177e4 LT	170	{
	171	/*
	172	* Refresh the timer.
	173	*/
f92d3749	174	if (len) {
1da177e4 LT	175	if (!nowayout) {
	176	size_t i;
	177
	178	/* In case it was set long ago */
	179	expect_close = 0;
	180
	181	for (i = 0; i != len; i++) {
	182	char c;
	183
	184	if (get_user(c, data + i))
	185	return -EFAULT;
	186	if (c == 'V')
	187	expect_close = 42;
	188	}
	189	}
	190	softdog_keepalive();
	191	}
	192	return len;
	193	}
	194
f92d3749 AC	195	static long softdog_ioctl(struct file *file, unsigned int cmd,
f92d3749 AC	196	unsigned long arg)
1da177e4 LT	197	{
	198	void __user argp = (void __user )arg;
	199	int __user *p = argp;
	200	int new_margin;
f92d3749	201	static const struct watchdog_info ident = {
1da177e4 LT	202	.options = WDIOF_SETTIMEOUT \|
	203	WDIOF_KEEPALIVEPING \|
	204	WDIOF_MAGICCLOSE,
	205	.firmware_version = 0,
	206	.identity = "Software Watchdog",
	207	};
	208	switch (cmd) {
f92d3749 AC	209	case WDIOC_GETSUPPORT:
	210	return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	211	case WDIOC_GETSTATUS:
	212	case WDIOC_GETBOOTSTATUS:
	213	return put_user(0, p);
	214	case WDIOC_KEEPALIVE:
	215	softdog_keepalive();
	216	return 0;
	217	case WDIOC_SETTIMEOUT:
	218	if (get_user(new_margin, p))
	219	return -EFAULT;
	220	if (softdog_set_heartbeat(new_margin))
	221	return -EINVAL;
	222	softdog_keepalive();
	223	/* Fall */
	224	case WDIOC_GETTIMEOUT:
	225	return put_user(soft_margin, p);
0c06090c WVS	226	default:
0c06090c WVS	227	return -ENOTTY;
1da177e4 LT	228	}
	229	}
	230
	231	/*
	232	* Notifier for system down
	233	*/
	234
	235	static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
	236	void *unused)
	237	{
f92d3749	238	if (code == SYS_DOWN \|\| code == SYS_HALT)
1da177e4 LT	239	/* Turn the WDT off */
1da177e4 LT	240	softdog_stop();
1da177e4 LT	241	return NOTIFY_DONE;
	242	}
	243
	244	/*
	245	* Kernel Interfaces
	246	*/
	247
62322d25	248	static const struct file_operations softdog_fops = {
1da177e4 LT	249	.owner = THIS_MODULE,
	250	.llseek = no_llseek,
	251	.write = softdog_write,
f92d3749	252	.unlocked_ioctl = softdog_ioctl,
1da177e4 LT	253	.open = softdog_open,
	254	.release = softdog_release,
	255	};
	256
	257	static struct miscdevice softdog_miscdev = {
	258	.minor = WATCHDOG_MINOR,
	259	.name = "watchdog",
	260	.fops = &softdog_fops,
	261	};
	262
	263	static struct notifier_block softdog_notifier = {
	264	.notifier_call = softdog_notify_sys,
	265	};
	266
	267	static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
	268
	269	static int __init watchdog_init(void)
	270	{
	271	int ret;
	272
f92d3749 AC	273	/* Check that the soft_margin value is within it's range;
f92d3749 AC	274	if not reset to the default */
1da177e4 LT	275	if (softdog_set_heartbeat(soft_margin)) {
1da177e4 LT	276	softdog_set_heartbeat(TIMER_MARGIN);
f92d3749 AC	277	printk(KERN_INFO PFX
f92d3749 AC	278	"soft_margin must be 0 < soft_margin < 65536, using %d\n",
1da177e4 LT	279	TIMER_MARGIN);
	280	}
	281
	282	ret = register_reboot_notifier(&softdog_notifier);
	283	if (ret) {
f92d3749 AC	284	printk(KERN_ERR PFX
f92d3749 AC	285	"cannot register reboot notifier (err=%d)\n", ret);
1da177e4 LT	286	return ret;
	287	}
	288
	289	ret = misc_register(&softdog_miscdev);
	290	if (ret) {
f92d3749 AC	291	printk(KERN_ERR PFX
	292	"cannot register miscdev on minor=%d (err=%d)\n",
	293	WATCHDOG_MINOR, ret);
1da177e4 LT	294	unregister_reboot_notifier(&softdog_notifier);
	295	return ret;
	296	}
	297
	298	printk(banner, soft_noboot, soft_margin, nowayout);
	299
	300	return 0;
	301	}
	302
	303	static void __exit watchdog_exit(void)
	304	{
	305	misc_deregister(&softdog_miscdev);
	306	unregister_reboot_notifier(&softdog_notifier);
	307	}
	308
	309	module_init(watchdog_init);
	310	module_exit(watchdog_exit);
	311
	312	MODULE_AUTHOR("Alan Cox");
	313	MODULE_DESCRIPTION("Software Watchdog Device Driver");
	314	MODULE_LICENSE("GPL");
	315	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);