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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 | |
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> | |
696f9486 | 47 | #include <linux/smp_lock.h> |
1da177e4 | 48 | #include <linux/init.h> |
696f9486 | 49 | #include <linux/delay.h> |
1da177e4 | 50 | #include <asm/uaccess.h> |
696f9486 | 51 | #include <linux/sysrq.h> |
1da177e4 LT |
52 | |
53 | ||
696f9486 | 54 | #define VERSION_STR "0.9.0" |
1da177e4 LT |
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 */ | |
696f9486 | 62 | static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */ |
1da177e4 | 63 | |
696f9486 | 64 | /* options - modular */ |
1da177e4 LT |
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."); | |
696f9486 JB |
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."); | |
1da177e4 | 73 | |
696f9486 | 74 | MODULE_AUTHOR("Oracle"); |
1da177e4 LT |
75 | MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin."); |
76 | MODULE_LICENSE("GPL"); | |
696f9486 JB |
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 | ||
0d078f6f | 120 | #if defined(CONFIG_X86) |
696f9486 JB |
121 | # define HAVE_MONOTONIC |
122 | # define TIMER_FREQ 1000000000ULL | |
347a8dc3 | 123 | #elif defined(CONFIG_S390) |
696f9486 JB |
124 | /* FA240000 is 1 Second in the IBM time universe (Page 4-38 Principles of Op for zSeries */ |
125 | # define TIMER_FREQ 0xFA240000ULL | |
126 | #elif defined(CONFIG_IA64) | |
127 | # define TIMER_FREQ ((unsigned long long)local_cpu_data->itc_freq) | |
128 | #elif defined(CONFIG_PPC64) | |
129 | # define TIMER_FREQ (HZ*loops_per_jiffy) | |
130 | #endif | |
131 | ||
132 | #ifdef HAVE_MONOTONIC | |
133 | extern unsigned long long monotonic_clock(void); | |
134 | #else | |
135 | static inline unsigned long long monotonic_clock(void) | |
136 | { | |
137 | # ifdef __s390__ | |
138 | /* returns the TOD. see 4-38 Principles of Op of zSeries */ | |
139 | return get_clock(); | |
140 | # else | |
141 | return get_cycles(); | |
142 | # endif /* __s390__ */ | |
143 | } | |
144 | #endif /* HAVE_MONOTONIC */ | |
1da177e4 LT |
145 | |
146 | ||
147 | /* Last time scheduled */ | |
148 | static unsigned long long hangcheck_tsc, hangcheck_tsc_margin; | |
149 | ||
150 | static void hangcheck_fire(unsigned long); | |
151 | ||
8d06afab | 152 | static DEFINE_TIMER(hangcheck_ticktock, hangcheck_fire, 0, 0); |
1da177e4 | 153 | |
1da177e4 LT |
154 | |
155 | static void hangcheck_fire(unsigned long data) | |
156 | { | |
157 | unsigned long long cur_tsc, tsc_diff; | |
158 | ||
159 | cur_tsc = monotonic_clock(); | |
160 | ||
161 | if (cur_tsc > hangcheck_tsc) | |
162 | tsc_diff = cur_tsc - hangcheck_tsc; | |
163 | else | |
164 | tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */ | |
165 | ||
166 | if (tsc_diff > hangcheck_tsc_margin) { | |
696f9486 JB |
167 | if (hangcheck_dump_tasks) { |
168 | printk(KERN_CRIT "Hangcheck: Task state:\n"); | |
169 | #ifdef CONFIG_MAGIC_SYSRQ | |
170 | handle_sysrq('t', NULL, NULL); | |
171 | #endif /* CONFIG_MAGIC_SYSRQ */ | |
172 | } | |
1da177e4 LT |
173 | if (hangcheck_reboot) { |
174 | printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n"); | |
970d3244 | 175 | emergency_restart(); |
1da177e4 LT |
176 | } else { |
177 | printk(KERN_CRIT "Hangcheck: hangcheck value past margin!\n"); | |
178 | } | |
179 | } | |
180 | mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ)); | |
181 | hangcheck_tsc = monotonic_clock(); | |
182 | } | |
183 | ||
184 | ||
185 | static int __init hangcheck_init(void) | |
186 | { | |
187 | printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n", | |
188 | VERSION_STR, hangcheck_tick, hangcheck_margin); | |
696f9486 JB |
189 | #if defined (HAVE_MONOTONIC) |
190 | printk("Hangcheck: Using monotonic_clock().\n"); | |
191 | #elif defined(__s390__) | |
192 | printk("Hangcheck: Using TOD.\n"); | |
193 | #else | |
194 | printk("Hangcheck: Using get_cycles().\n"); | |
195 | #endif /* HAVE_MONOTONIC */ | |
196 | hangcheck_tsc_margin = | |
197 | (unsigned long long)(hangcheck_margin + hangcheck_tick); | |
198 | hangcheck_tsc_margin *= (unsigned long long)TIMER_FREQ; | |
1da177e4 LT |
199 | |
200 | hangcheck_tsc = monotonic_clock(); | |
201 | mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ)); | |
202 | ||
203 | return 0; | |
204 | } | |
205 | ||
206 | ||
207 | static void __exit hangcheck_exit(void) | |
208 | { | |
209 | del_timer_sync(&hangcheck_ticktock); | |
696f9486 | 210 | printk("Hangcheck: Stopped hangcheck timer.\n"); |
1da177e4 LT |
211 | } |
212 | ||
213 | module_init(hangcheck_init); | |
214 | module_exit(hangcheck_exit); |