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1da177e4 LT |
1 | /* |
2 | * hangcheck-timer.c | |
3 | * | |
4 | * Driver for a little io fencing timer. | |
5 | * | |
696f9486 | 6 | * Copyright (C) 2002, 2003 Oracle. All rights reserved. |
1da177e4 LT |
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 | |
8dfba4d7 | 29 | * margin of error. The hangcheck_tick module parameter takes the timer |
1da177e4 LT |
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> | |
696f9486 | 48 | #include <linux/delay.h> |
1da177e4 | 49 | #include <asm/uaccess.h> |
696f9486 | 50 | #include <linux/sysrq.h> |
e8edc6e0 | 51 | #include <linux/timer.h> |
1da177e4 | 52 | |
696f9486 | 53 | #define VERSION_STR "0.9.0" |
1da177e4 LT |
54 | |
55 | #define DEFAULT_IOFENCE_MARGIN 60 /* Default fudge factor, in seconds */ | |
56 | #define DEFAULT_IOFENCE_TICK 180 /* Default timer timeout, in seconds */ | |
57 | ||
58 | static int hangcheck_tick = DEFAULT_IOFENCE_TICK; | |
59 | static int hangcheck_margin = DEFAULT_IOFENCE_MARGIN; | |
60 | static int hangcheck_reboot; /* Defaults to not reboot */ | |
696f9486 | 61 | static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */ |
1da177e4 | 62 | |
696f9486 | 63 | /* options - modular */ |
1da177e4 LT |
64 | module_param(hangcheck_tick, int, 0); |
65 | MODULE_PARM_DESC(hangcheck_tick, "Timer delay."); | |
66 | module_param(hangcheck_margin, int, 0); | |
67 | MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire."); | |
68 | module_param(hangcheck_reboot, int, 0); | |
69 | MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded."); | |
696f9486 JB |
70 | module_param(hangcheck_dump_tasks, int, 0); |
71 | MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded."); | |
1da177e4 | 72 | |
696f9486 | 73 | MODULE_AUTHOR("Oracle"); |
1da177e4 LT |
74 | MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin."); |
75 | MODULE_LICENSE("GPL"); | |
696f9486 JB |
76 | MODULE_VERSION(VERSION_STR); |
77 | ||
78 | /* options - nonmodular */ | |
79 | #ifndef MODULE | |
80 | ||
81 | static int __init hangcheck_parse_tick(char *str) | |
82 | { | |
83 | int par; | |
84 | if (get_option(&str,&par)) | |
85 | hangcheck_tick = par; | |
86 | return 1; | |
87 | } | |
88 | ||
89 | static int __init hangcheck_parse_margin(char *str) | |
90 | { | |
91 | int par; | |
92 | if (get_option(&str,&par)) | |
93 | hangcheck_margin = par; | |
94 | return 1; | |
95 | } | |
96 | ||
97 | static int __init hangcheck_parse_reboot(char *str) | |
98 | { | |
99 | int par; | |
100 | if (get_option(&str,&par)) | |
101 | hangcheck_reboot = par; | |
102 | return 1; | |
103 | } | |
104 | ||
105 | static int __init hangcheck_parse_dump_tasks(char *str) | |
106 | { | |
107 | int par; | |
108 | if (get_option(&str,&par)) | |
109 | hangcheck_dump_tasks = par; | |
110 | return 1; | |
111 | } | |
112 | ||
113 | __setup("hcheck_tick", hangcheck_parse_tick); | |
114 | __setup("hcheck_margin", hangcheck_parse_margin); | |
115 | __setup("hcheck_reboot", hangcheck_parse_reboot); | |
116 | __setup("hcheck_dump_tasks", hangcheck_parse_dump_tasks); | |
117 | #endif /* not MODULE */ | |
118 | ||
1489939f | 119 | #if defined(CONFIG_S390) |
696f9486 JB |
120 | # define HAVE_MONOTONIC |
121 | # define TIMER_FREQ 1000000000ULL | |
696f9486 JB |
122 | #elif defined(CONFIG_IA64) |
123 | # define TIMER_FREQ ((unsigned long long)local_cpu_data->itc_freq) | |
ede65f39 | 124 | #else |
696f9486 JB |
125 | # define TIMER_FREQ (HZ*loops_per_jiffy) |
126 | #endif | |
127 | ||
128 | #ifdef HAVE_MONOTONIC | |
129 | extern unsigned long long monotonic_clock(void); | |
130 | #else | |
131 | static inline unsigned long long monotonic_clock(void) | |
132 | { | |
696f9486 | 133 | return get_cycles(); |
696f9486 JB |
134 | } |
135 | #endif /* HAVE_MONOTONIC */ | |
1da177e4 LT |
136 | |
137 | ||
138 | /* Last time scheduled */ | |
139 | static unsigned long long hangcheck_tsc, hangcheck_tsc_margin; | |
140 | ||
141 | static void hangcheck_fire(unsigned long); | |
142 | ||
8d06afab | 143 | static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0); |
1da177e4 | 144 | |
1da177e4 LT |
145 | |
146 | static void hangcheck_fire(unsigned long data) | |
147 | { | |
148 | unsigned long long cur_tsc, tsc_diff; | |
149 | ||
150 | cur_tsc = monotonic_clock(); | |
151 | ||
152 | if (cur_tsc > hangcheck_tsc) | |
153 | tsc_diff = cur_tsc - hangcheck_tsc; | |
154 | else | |
155 | tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */ | |
156 | ||
157 | if (tsc_diff > hangcheck_tsc_margin) { | |
696f9486 JB |
158 | if (hangcheck_dump_tasks) { |
159 | printk(KERN_CRIT "Hangcheck: Task state:\n"); | |
160 | #ifdef CONFIG_MAGIC_SYSRQ | |
7d12e780 | 161 | handle_sysrq('t', NULL); |
696f9486 JB |
162 | #endif /* CONFIG_MAGIC_SYSRQ */ |
163 | } | |
1da177e4 LT |
164 | if (hangcheck_reboot) { |
165 | printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n"); | |
970d3244 | 166 | emergency_restart(); |
1da177e4 LT |
167 | } else { |
168 | printk(KERN_CRIT "Hangcheck: hangcheck value past margin!\n"); | |
169 | } | |
170 | } | |
171 | mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ)); | |
172 | hangcheck_tsc = monotonic_clock(); | |
173 | } | |
174 | ||
175 | ||
176 | static int __init hangcheck_init(void) | |
177 | { | |
178 | printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n", | |
179 | VERSION_STR, hangcheck_tick, hangcheck_margin); | |
696f9486 JB |
180 | #if defined (HAVE_MONOTONIC) |
181 | printk("Hangcheck: Using monotonic_clock().\n"); | |
696f9486 JB |
182 | #else |
183 | printk("Hangcheck: Using get_cycles().\n"); | |
184 | #endif /* HAVE_MONOTONIC */ | |
185 | hangcheck_tsc_margin = | |
186 | (unsigned long long)(hangcheck_margin + hangcheck_tick); | |
187 | hangcheck_tsc_margin *= (unsigned long long)TIMER_FREQ; | |
1da177e4 LT |
188 | |
189 | hangcheck_tsc = monotonic_clock(); | |
190 | mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ)); | |
191 | ||
192 | return 0; | |
193 | } | |
194 | ||
195 | ||
196 | static void __exit hangcheck_exit(void) | |
197 | { | |
198 | del_timer_sync(&hangcheck_ticktock); | |
696f9486 | 199 | printk("Hangcheck: Stopped hangcheck timer.\n"); |
1da177e4 LT |
200 | } |
201 | ||
202 | module_init(hangcheck_init); | |
203 | module_exit(hangcheck_exit); |