316 lines
7.2 KiB
C
316 lines
7.2 KiB
C
/*
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* SoftDog 0.07: A Software Watchdog Device
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*
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* (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
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* http://www.redhat.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
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* warranty for any of this software. This material is provided
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* "AS-IS" and at no charge.
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*
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* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
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*
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* Software only watchdog driver. Unlike its big brother the WDT501P
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* driver this won't always recover a failed machine.
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*
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* 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
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* Modularised.
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* Added soft_margin; use upon insmod to change the timer delay.
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* NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
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* minors.
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*
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* 19980911 Alan Cox
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* Made SMP safe for 2.3.x
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*
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* 20011127 Joel Becker (jlbec@evilplan.org>
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* Added soft_noboot; Allows testing the softdog trigger without
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* requiring a recompile.
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* Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
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*
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* 20020530 Joel Becker <joel.becker@oracle.com>
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* Added Matt Domsch's nowayout module option.
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*/
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/types.h>
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#include <linux/timer.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/fs.h>
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#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/init.h>
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#include <linux/jiffies.h>
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#include <linux/uaccess.h>
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#define PFX "SoftDog: "
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#define TIMER_MARGIN 60 /* Default is 60 seconds */
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static int soft_margin = TIMER_MARGIN; /* in seconds */
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module_param(soft_margin, int, 0);
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MODULE_PARM_DESC(soft_margin,
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"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
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__MODULE_STRING(TIMER_MARGIN) ")");
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static int nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, int, 0);
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MODULE_PARM_DESC(nowayout,
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"Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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#ifdef ONLY_TESTING
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static int soft_noboot = 1;
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#else
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static int soft_noboot = 0;
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#endif /* ONLY_TESTING */
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module_param(soft_noboot, int, 0);
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MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
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/*
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* Our timer
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*/
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static void watchdog_fire(unsigned long);
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static struct timer_list watchdog_ticktock =
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TIMER_INITIALIZER(watchdog_fire, 0, 0);
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static unsigned long driver_open, orphan_timer;
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static char expect_close;
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/*
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* If the timer expires..
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*/
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static void watchdog_fire(unsigned long data)
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{
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if (test_and_clear_bit(0, &orphan_timer))
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module_put(THIS_MODULE);
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if (soft_noboot)
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printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
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else {
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printk(KERN_CRIT PFX "Initiating system reboot.\n");
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emergency_restart();
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printk(KERN_CRIT PFX "Reboot didn't ?????\n");
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}
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}
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/*
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* Softdog operations
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*/
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static int softdog_keepalive(void)
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{
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mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
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return 0;
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}
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static int softdog_stop(void)
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{
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del_timer(&watchdog_ticktock);
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return 0;
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}
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static int softdog_set_heartbeat(int t)
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{
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if ((t < 0x0001) || (t > 0xFFFF))
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return -EINVAL;
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soft_margin = t;
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return 0;
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}
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/*
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* /dev/watchdog handling
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*/
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static int softdog_open(struct inode *inode, struct file *file)
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{
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if (test_and_set_bit(0, &driver_open))
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return -EBUSY;
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if (!test_and_clear_bit(0, &orphan_timer))
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__module_get(THIS_MODULE);
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/*
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* Activate timer
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*/
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softdog_keepalive();
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return nonseekable_open(inode, file);
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}
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static int softdog_release(struct inode *inode, struct file *file)
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{
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/*
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* Shut off the timer.
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* Lock it in if it's a module and we set nowayout
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*/
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if (expect_close == 42) {
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softdog_stop();
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module_put(THIS_MODULE);
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} else {
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printk(KERN_CRIT PFX
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"Unexpected close, not stopping watchdog!\n");
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set_bit(0, &orphan_timer);
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softdog_keepalive();
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}
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clear_bit(0, &driver_open);
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expect_close = 0;
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return 0;
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}
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static ssize_t softdog_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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{
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/*
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* Refresh the timer.
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*/
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if (len) {
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if (!nowayout) {
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size_t i;
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/* In case it was set long ago */
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expect_close = 0;
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for (i = 0; i != len; i++) {
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char c;
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if (get_user(c, data + i))
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return -EFAULT;
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if (c == 'V')
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expect_close = 42;
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}
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}
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softdog_keepalive();
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}
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return len;
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}
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static long softdog_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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int new_margin;
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static const struct watchdog_info ident = {
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.options = WDIOF_SETTIMEOUT |
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WDIOF_KEEPALIVEPING |
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WDIOF_MAGICCLOSE,
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.firmware_version = 0,
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.identity = "Software Watchdog",
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};
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, p);
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case WDIOC_KEEPALIVE:
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softdog_keepalive();
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return 0;
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case WDIOC_SETTIMEOUT:
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if (get_user(new_margin, p))
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return -EFAULT;
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if (softdog_set_heartbeat(new_margin))
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return -EINVAL;
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softdog_keepalive();
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/* Fall */
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case WDIOC_GETTIMEOUT:
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return put_user(soft_margin, p);
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default:
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return -ENOTTY;
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}
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}
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/*
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* Notifier for system down
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*/
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static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
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void *unused)
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{
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if (code == SYS_DOWN || code == SYS_HALT)
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/* Turn the WDT off */
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softdog_stop();
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return NOTIFY_DONE;
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}
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/*
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* Kernel Interfaces
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*/
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static const struct file_operations softdog_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = softdog_write,
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.unlocked_ioctl = softdog_ioctl,
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.open = softdog_open,
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.release = softdog_release,
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};
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static struct miscdevice softdog_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &softdog_fops,
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};
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static struct notifier_block softdog_notifier = {
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.notifier_call = softdog_notify_sys,
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};
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static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
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static int __init watchdog_init(void)
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{
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int ret;
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/* Check that the soft_margin value is within it's range;
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if not reset to the default */
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if (softdog_set_heartbeat(soft_margin)) {
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softdog_set_heartbeat(TIMER_MARGIN);
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printk(KERN_INFO PFX
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"soft_margin must be 0 < soft_margin < 65536, using %d\n",
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TIMER_MARGIN);
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}
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ret = register_reboot_notifier(&softdog_notifier);
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if (ret) {
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printk(KERN_ERR PFX
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"cannot register reboot notifier (err=%d)\n", ret);
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return ret;
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}
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ret = misc_register(&softdog_miscdev);
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if (ret) {
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printk(KERN_ERR PFX
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"cannot register miscdev on minor=%d (err=%d)\n",
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WATCHDOG_MINOR, ret);
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unregister_reboot_notifier(&softdog_notifier);
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return ret;
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}
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printk(banner, soft_noboot, soft_margin, nowayout);
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return 0;
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}
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static void __exit watchdog_exit(void)
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{
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misc_deregister(&softdog_miscdev);
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unregister_reboot_notifier(&softdog_notifier);
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}
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module_init(watchdog_init);
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module_exit(watchdog_exit);
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MODULE_AUTHOR("Alan Cox");
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MODULE_DESCRIPTION("Software Watchdog Device Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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