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1/*
2 * hangcheck-timer.c
3 *
4 * Driver for a little io fencing timer.
5 *
6 * Copyright (C) 2002, 2003 Oracle. All rights reserved.
7 *
8 * Author: Joel Becker <joel.becker@oracle.com>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public
12 * License version 2 as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public
20 * License along with this program; if not, write to the
21 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
22 * Boston, MA 021110-1307, USA.
23 */
24
25/*
26 * The hangcheck-timer driver uses the TSC to catch delays that
27 * jiffies does not notice. A timer is set. When the timer fires, it
28 * checks whether it was delayed and if that delay exceeds a given
29 * margin of error. The hangcheck_tick module parameter takes the timer
30 * duration in seconds. The hangcheck_margin parameter defines the
31 * margin of error, in seconds. The defaults are 60 seconds for the
32 * timer and 180 seconds for the margin of error. IOW, a timer is set
33 * for 60 seconds. When the timer fires, the callback checks the
34 * actual duration that the timer waited. If the duration exceeds the
35 * alloted time and margin (here 60 + 180, or 240 seconds), the machine
36 * is restarted. A healthy machine will have the duration match the
37 * expected timeout very closely.
38 */
39
40#include <linux/module.h>
41#include <linux/moduleparam.h>
42#include <linux/types.h>
43#include <linux/kernel.h>
44#include <linux/fs.h>
45#include <linux/mm.h>
46#include <linux/reboot.h>
47#include <linux/init.h>
48#include <linux/delay.h>
49#include <asm/uaccess.h>
50#include <linux/sysrq.h>
51#include <linux/timer.h>
52#include <linux/time.h>
53
54#define VERSION_STR "0.9.1"
55
56#define DEFAULT_IOFENCE_MARGIN 60 /* Default fudge factor, in seconds */
57#define DEFAULT_IOFENCE_TICK 180 /* Default timer timeout, in seconds */
58
59static int hangcheck_tick = DEFAULT_IOFENCE_TICK;
60static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN;
61static int hangcheck_reboot; /* Defaults to not reboot */
62static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */
63
64/* options - modular */
65module_param(hangcheck_tick, int, 0);
66MODULE_PARM_DESC(hangcheck_tick, "Timer delay.");
67module_param(hangcheck_margin, int, 0);
68MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire.");
69module_param(hangcheck_reboot, int, 0);
70MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded.");
71module_param(hangcheck_dump_tasks, int, 0);
72MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded.");
73
74MODULE_AUTHOR("Oracle");
75MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin.");
76MODULE_LICENSE("GPL");
77MODULE_VERSION(VERSION_STR);
78
79/* options - nonmodular */
80#ifndef MODULE
81
82static int __init hangcheck_parse_tick(char *str)
83{
84 int par;
85 if (get_option(&str,&par))
86 hangcheck_tick = par;
87 return 1;
88}
89
90static int __init hangcheck_parse_margin(char *str)
91{
92 int par;
93 if (get_option(&str,&par))
94 hangcheck_margin = par;
95 return 1;
96}
97
98static int __init hangcheck_parse_reboot(char *str)
99{
100 int par;
101 if (get_option(&str,&par))
102 hangcheck_reboot = par;
103 return 1;
104}
105
106static int __init hangcheck_parse_dump_tasks(char *str)
107{
108 int par;
109 if (get_option(&str,&par))
110 hangcheck_dump_tasks = par;
111 return 1;
112}
113
114__setup("hcheck_tick", hangcheck_parse_tick);
115__setup("hcheck_margin", hangcheck_parse_margin);
116__setup("hcheck_reboot", hangcheck_parse_reboot);
117__setup("hcheck_dump_tasks", hangcheck_parse_dump_tasks);
118#endif /* not MODULE */
119
120#if defined(CONFIG_S390)
121# define HAVE_MONOTONIC
122# define TIMER_FREQ 1000000000ULL
123#else
124# define TIMER_FREQ 1000000000ULL
125#endif
126
127#ifdef HAVE_MONOTONIC
128extern unsigned long long monotonic_clock(void);
129#else
130static inline unsigned long long monotonic_clock(void)
131{
132 struct timespec ts;
133 getrawmonotonic(&ts);
134 return timespec_to_ns(&ts);
135}
136#endif /* HAVE_MONOTONIC */
137
138
139/* Last time scheduled */
140static unsigned long long hangcheck_tsc, hangcheck_tsc_margin;
141
142static void hangcheck_fire(unsigned long);
143
144static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0);
145
146
147static void hangcheck_fire(unsigned long data)
148{
149 unsigned long long cur_tsc, tsc_diff;
150
151 cur_tsc = monotonic_clock();
152
153 if (cur_tsc > hangcheck_tsc)
154 tsc_diff = cur_tsc - hangcheck_tsc;
155 else
156 tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */
157
158 if (tsc_diff > hangcheck_tsc_margin) {
159 if (hangcheck_dump_tasks) {
160 printk(KERN_CRIT "Hangcheck: Task state:\n");
161#ifdef CONFIG_MAGIC_SYSRQ
162 handle_sysrq('t');
163#endif /* CONFIG_MAGIC_SYSRQ */
164 }
165 if (hangcheck_reboot) {
166 printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n");
167 emergency_restart();
168 } else {
169 printk(KERN_CRIT "Hangcheck: hangcheck value past margin!\n");
170 }
171 }
172#if 0
173 /*
174 * Enable to investigate delays in detail
175 */
176 printk("Hangcheck: called %Ld ns since last time (%Ld ns overshoot)\n",
177 tsc_diff, tsc_diff - hangcheck_tick*TIMER_FREQ);
178#endif
179 mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
180 hangcheck_tsc = monotonic_clock();
181}
182
183
184static int __init hangcheck_init(void)
185{
186 printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
187 VERSION_STR, hangcheck_tick, hangcheck_margin);
188#if defined (HAVE_MONOTONIC)
189 printk("Hangcheck: Using monotonic_clock().\n");
190#else
191 printk("Hangcheck: Using getrawmonotonic().\n");
192#endif /* HAVE_MONOTONIC */
193 hangcheck_tsc_margin =
194 (unsigned long long)(hangcheck_margin + hangcheck_tick);
195 hangcheck_tsc_margin *= (unsigned long long)TIMER_FREQ;
196
197 hangcheck_tsc = monotonic_clock();
198 mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
199
200 return 0;
201}
202
203
204static void __exit hangcheck_exit(void)
205{
206 del_timer_sync(&hangcheck_ticktock);
207 printk("Hangcheck: Stopped hangcheck timer.\n");
208}
209
210module_init(hangcheck_init);
211module_exit(hangcheck_exit);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * hangcheck-timer.c
4 *
5 * Driver for a little io fencing timer.
6 *
7 * Copyright (C) 2002, 2003 Oracle. All rights reserved.
8 *
9 * Author: Joel Becker <joel.becker@oracle.com>
10 */
11
12/*
13 * The hangcheck-timer driver uses the TSC to catch delays that
14 * jiffies does not notice. A timer is set. When the timer fires, it
15 * checks whether it was delayed and if that delay exceeds a given
16 * margin of error. The hangcheck_tick module parameter takes the timer
17 * duration in seconds. The hangcheck_margin parameter defines the
18 * margin of error, in seconds. The defaults are 60 seconds for the
19 * timer and 180 seconds for the margin of error. IOW, a timer is set
20 * for 60 seconds. When the timer fires, the callback checks the
21 * actual duration that the timer waited. If the duration exceeds the
22 * allotted time and margin (here 60 + 180, or 240 seconds), the machine
23 * is restarted. A healthy machine will have the duration match the
24 * expected timeout very closely.
25 */
26
27#include <linux/module.h>
28#include <linux/moduleparam.h>
29#include <linux/types.h>
30#include <linux/kernel.h>
31#include <linux/fs.h>
32#include <linux/mm.h>
33#include <linux/reboot.h>
34#include <linux/init.h>
35#include <linux/delay.h>
36#include <linux/uaccess.h>
37#include <linux/sysrq.h>
38#include <linux/timer.h>
39#include <linux/hrtimer.h>
40
41#define VERSION_STR "0.9.1"
42
43#define DEFAULT_IOFENCE_MARGIN 60 /* Default fudge factor, in seconds */
44#define DEFAULT_IOFENCE_TICK 180 /* Default timer timeout, in seconds */
45
46static int hangcheck_tick = DEFAULT_IOFENCE_TICK;
47static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN;
48static int hangcheck_reboot; /* Defaults to not reboot */
49static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */
50
51/* options - modular */
52module_param(hangcheck_tick, int, 0);
53MODULE_PARM_DESC(hangcheck_tick, "Timer delay.");
54module_param(hangcheck_margin, int, 0);
55MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire.");
56module_param(hangcheck_reboot, int, 0);
57MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded.");
58module_param(hangcheck_dump_tasks, int, 0);
59MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded.");
60
61MODULE_AUTHOR("Oracle");
62MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin.");
63MODULE_LICENSE("GPL");
64MODULE_VERSION(VERSION_STR);
65
66/* options - nonmodular */
67#ifndef MODULE
68
69static int __init hangcheck_parse_tick(char *str)
70{
71 int par;
72 if (get_option(&str,&par))
73 hangcheck_tick = par;
74 return 1;
75}
76
77static int __init hangcheck_parse_margin(char *str)
78{
79 int par;
80 if (get_option(&str,&par))
81 hangcheck_margin = par;
82 return 1;
83}
84
85static int __init hangcheck_parse_reboot(char *str)
86{
87 int par;
88 if (get_option(&str,&par))
89 hangcheck_reboot = par;
90 return 1;
91}
92
93static int __init hangcheck_parse_dump_tasks(char *str)
94{
95 int par;
96 if (get_option(&str,&par))
97 hangcheck_dump_tasks = par;
98 return 1;
99}
100
101__setup("hcheck_tick", hangcheck_parse_tick);
102__setup("hcheck_margin", hangcheck_parse_margin);
103__setup("hcheck_reboot", hangcheck_parse_reboot);
104__setup("hcheck_dump_tasks", hangcheck_parse_dump_tasks);
105#endif /* not MODULE */
106
107#define TIMER_FREQ 1000000000ULL
108
109/* Last time scheduled */
110static unsigned long long hangcheck_tsc, hangcheck_tsc_margin;
111
112static void hangcheck_fire(struct timer_list *);
113
114static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire);
115
116static void hangcheck_fire(struct timer_list *unused)
117{
118 unsigned long long cur_tsc, tsc_diff;
119
120 cur_tsc = ktime_get_ns();
121
122 if (cur_tsc > hangcheck_tsc)
123 tsc_diff = cur_tsc - hangcheck_tsc;
124 else
125 tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */
126
127 if (tsc_diff > hangcheck_tsc_margin) {
128 if (hangcheck_dump_tasks) {
129 printk(KERN_CRIT "Hangcheck: Task state:\n");
130#ifdef CONFIG_MAGIC_SYSRQ
131 handle_sysrq('t');
132#endif /* CONFIG_MAGIC_SYSRQ */
133 }
134 if (hangcheck_reboot) {
135 printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n");
136 emergency_restart();
137 } else {
138 printk(KERN_CRIT "Hangcheck: hangcheck value past margin!\n");
139 }
140 }
141#if 0
142 /*
143 * Enable to investigate delays in detail
144 */
145 printk("Hangcheck: called %Ld ns since last time (%Ld ns overshoot)\n",
146 tsc_diff, tsc_diff - hangcheck_tick*TIMER_FREQ);
147#endif
148 mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
149 hangcheck_tsc = ktime_get_ns();
150}
151
152
153static int __init hangcheck_init(void)
154{
155 printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
156 VERSION_STR, hangcheck_tick, hangcheck_margin);
157 hangcheck_tsc_margin =
158 (unsigned long long)hangcheck_margin + hangcheck_tick;
159 hangcheck_tsc_margin *= TIMER_FREQ;
160
161 hangcheck_tsc = ktime_get_ns();
162 mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
163
164 return 0;
165}
166
167
168static void __exit hangcheck_exit(void)
169{
170 del_timer_sync(&hangcheck_ticktock);
171 printk("Hangcheck: Stopped hangcheck timer.\n");
172}
173
174module_init(hangcheck_init);
175module_exit(hangcheck_exit);