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 paramter 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/smp_lock.h>
48 #include <linux/init.h>
49 #include <linux/delay.h>
50 #include <asm/uaccess.h>
51 #include <linux/sysrq.h>
52
53
54 #define VERSION_STR "0.9.0"
55
56 #define DEFAULT_IOFENCE_MARGIN 60 /* Default fudge factor, in seconds */
57 #define DEFAULT_IOFENCE_TICK 180 /* Default timer timeout, in seconds */
58
59 static int hangcheck_tick = DEFAULT_IOFENCE_TICK;
60 static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN;
61 static int hangcheck_reboot; /* Defaults to not reboot */
62 static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */
63
64 /* options - modular */
65 module_param(hangcheck_tick, int, 0);
66 MODULE_PARM_DESC(hangcheck_tick, "Timer delay.");
67 module_param(hangcheck_margin, int, 0);
68 MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire.");
69 module_param(hangcheck_reboot, int, 0);
70 MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded.");
71 module_param(hangcheck_dump_tasks, int, 0);
72 MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded.");
73
74 MODULE_AUTHOR("Oracle");
75 MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin.");
76 MODULE_LICENSE("GPL");
77 MODULE_VERSION(VERSION_STR);
78
79 /* options - nonmodular */
80 #ifndef MODULE
81
82 static 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
90 static 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
98 static 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
106 static 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_X86) || defined(CONFIG_S390)
121 # define HAVE_MONOTONIC
122 # define TIMER_FREQ 1000000000ULL
123 #elif defined(CONFIG_IA64)
124 # define TIMER_FREQ ((unsigned long long)local_cpu_data->itc_freq)
125 #elif defined(CONFIG_PPC64)
126 # define TIMER_FREQ (HZ*loops_per_jiffy)
127 #endif
128
129 #ifdef HAVE_MONOTONIC
130 extern unsigned long long monotonic_clock(void);
131 #else
132 static inline unsigned long long monotonic_clock(void)
133 {
134 return get_cycles();
135 }
136 #endif /* HAVE_MONOTONIC */
137
138
139 /* Last time scheduled */
140 static unsigned long long hangcheck_tsc, hangcheck_tsc_margin;
141
142 static void hangcheck_fire(unsigned long);
143
144 static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0);
145
146
147 static 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', NULL, NULL);
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 mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
173 hangcheck_tsc = monotonic_clock();
174 }
175
176
177 static int __init hangcheck_init(void)
178 {
179 printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
180 VERSION_STR, hangcheck_tick, hangcheck_margin);
181 #if defined (HAVE_MONOTONIC)
182 printk("Hangcheck: Using monotonic_clock().\n");
183 #else
184 printk("Hangcheck: Using get_cycles().\n");
185 #endif /* HAVE_MONOTONIC */
186 hangcheck_tsc_margin =
187 (unsigned long long)(hangcheck_margin + hangcheck_tick);
188 hangcheck_tsc_margin *= (unsigned long long)TIMER_FREQ;
189
190 hangcheck_tsc = monotonic_clock();
191 mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
192
193 return 0;
194 }
195
196
197 static void __exit hangcheck_exit(void)
198 {
199 del_timer_sync(&hangcheck_ticktock);
200 printk("Hangcheck: Stopped hangcheck timer.\n");
201 }
202
203 module_init(hangcheck_init);
204 module_exit(hangcheck_exit);
205
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