LXR linux/drivers/watchdog/softdog.c

   1/*
   2 *      SoftDog:        A Software Watchdog Device
   3 *
   4 *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   5 *                                                      All Rights Reserved.
   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
  22#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  23
  24#include <linux/hrtimer.h>
  25#include <linux/init.h>
  26#include <linux/kernel.h>
  27#include <linux/module.h>
  28#include <linux/moduleparam.h>
  29#include <linux/reboot.h>
  30#include <linux/types.h>
  31#include <linux/watchdog.h>
  32
  33#define TIMER_MARGIN    60              /* Default is 60 seconds */
  34static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
  35module_param(soft_margin, uint, 0);
  36MODULE_PARM_DESC(soft_margin,
  37        "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
  38                                        __MODULE_STRING(TIMER_MARGIN) ")");
  39
  40static bool nowayout = WATCHDOG_NOWAYOUT;
  41module_param(nowayout, bool, 0);
  42MODULE_PARM_DESC(nowayout,
  43                "Watchdog cannot be stopped once started (default="
  44                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  45
  46static int soft_noboot;
  47module_param(soft_noboot, int, 0);
  48MODULE_PARM_DESC(soft_noboot,
  49        "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
  50
  51static int soft_panic;
  52module_param(soft_panic, int, 0);
  53MODULE_PARM_DESC(soft_panic,
  54        "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
  55
  56static struct hrtimer softdog_ticktock;
  57static struct hrtimer softdog_preticktock;
  58
  59static enum hrtimer_restart softdog_fire(struct hrtimer *timer)
  60{
  61        module_put(THIS_MODULE);
  62        if (soft_noboot) {
  63                pr_crit("Triggered - Reboot ignored\n");
  64        } else if (soft_panic) {
  65                pr_crit("Initiating panic\n");
  66                panic("Software Watchdog Timer expired");
  67        } else {
  68                pr_crit("Initiating system reboot\n");
  69                emergency_restart();
  70                pr_crit("Reboot didn't ?????\n");
  71        }
  72
  73        return HRTIMER_NORESTART;
  74}
  75
  76static struct watchdog_device softdog_dev;
  77
  78static enum hrtimer_restart softdog_pretimeout(struct hrtimer *timer)
  79{
  80        watchdog_notify_pretimeout(&softdog_dev);
  81
  82        return HRTIMER_NORESTART;
  83}
  84
  85static int softdog_ping(struct watchdog_device *w)
  86{
  87        if (!hrtimer_active(&softdog_ticktock))
  88                __module_get(THIS_MODULE);
  89        hrtimer_start(&softdog_ticktock, ktime_set(w->timeout, 0),
  90                      HRTIMER_MODE_REL);
  91
  92        if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) {
  93                if (w->pretimeout)
  94                        hrtimer_start(&softdog_preticktock,
  95                                      ktime_set(w->timeout - w->pretimeout, 0),
  96                                      HRTIMER_MODE_REL);
  97                else
  98                        hrtimer_cancel(&softdog_preticktock);
  99        }
 100
 101        return 0;
 102}
 103
 104static int softdog_stop(struct watchdog_device *w)
 105{
 106        if (hrtimer_cancel(&softdog_ticktock))
 107                module_put(THIS_MODULE);
 108
 109        if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT))
 110                hrtimer_cancel(&softdog_preticktock);
 111
 112        return 0;
 113}
 114
 115static struct watchdog_info softdog_info = {
 116        .identity = "Software Watchdog",
 117        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 118};
 119
 120static const struct watchdog_ops softdog_ops = {
 121        .owner = THIS_MODULE,
 122        .start = softdog_ping,
 123        .stop = softdog_stop,
 124};
 125
 126static struct watchdog_device softdog_dev = {
 127        .info = &softdog_info,
 128        .ops = &softdog_ops,
 129        .min_timeout = 1,
 130        .max_timeout = 65535,
 131        .timeout = TIMER_MARGIN,
 132};
 133
 134static int __init softdog_init(void)
 135{
 136        int ret;
 137
 138        watchdog_init_timeout(&softdog_dev, soft_margin, NULL);
 139        watchdog_set_nowayout(&softdog_dev, nowayout);
 140        watchdog_stop_on_reboot(&softdog_dev);
 141
 142        hrtimer_init(&softdog_ticktock, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 143        softdog_ticktock.function = softdog_fire;
 144
 145        if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) {
 146                softdog_info.options |= WDIOF_PRETIMEOUT;
 147                hrtimer_init(&softdog_preticktock, CLOCK_MONOTONIC,
 148                             HRTIMER_MODE_REL);
 149                softdog_preticktock.function = softdog_pretimeout;
 150        }
 151
 152        ret = watchdog_register_device(&softdog_dev);
 153        if (ret)
 154                return ret;
 155
 156        pr_info("initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
 157                soft_noboot, softdog_dev.timeout, soft_panic, nowayout);
 158
 159        return 0;
 160}
 161module_init(softdog_init);
 162
 163static void __exit softdog_exit(void)
 164{
 165        watchdog_unregister_device(&softdog_dev);
 166}
 167module_exit(softdog_exit);
 168
 169MODULE_AUTHOR("Alan Cox");
 170MODULE_DESCRIPTION("Software Watchdog Device Driver");
 171MODULE_LICENSE("GPL");
 172