/* * SoftDog 0.07: A Software Watchdog Device * * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved. * http://www.redhat.com * * 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);