Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Detect hard and soft lockups on a system |
| 3 | * |
| 4 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. |
| 5 | * |
Fernando Luis Vázquez Cao | 86f5e6a | 2012-02-09 17:42:22 -0500 | [diff] [blame] | 6 | * Note: Most of this code is borrowed heavily from the original softlockup |
| 7 | * detector, so thanks to Ingo for the initial implementation. |
| 8 | * Some chunks also taken from the old x86-specific nmi watchdog code, thanks |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 9 | * to those contributors as well. |
| 10 | */ |
| 11 | |
Andrew Morton | 4501980 | 2012-03-23 15:01:55 -0700 | [diff] [blame] | 12 | #define pr_fmt(fmt) "NMI watchdog: " fmt |
| 13 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 14 | #include <linux/mm.h> |
| 15 | #include <linux/cpu.h> |
Olav Haugan | d8354e6 | 2016-08-18 16:49:44 -0700 | [diff] [blame] | 16 | #include <linux/device.h> |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 17 | #include <linux/nmi.h> |
| 18 | #include <linux/init.h> |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 19 | #include <linux/module.h> |
| 20 | #include <linux/sysctl.h> |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 21 | #include <linux/smpboot.h> |
Clark Williams | 8bd75c7 | 2013-02-07 09:47:07 -0600 | [diff] [blame] | 22 | #include <linux/sched/rt.h> |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 23 | #include <linux/tick.h> |
Tejun Heo | 82607adc | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 24 | #include <linux/workqueue.h> |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 25 | |
| 26 | #include <asm/irq_regs.h> |
Eric B Munson | 5d1c0f4 | 2012-03-10 14:37:28 -0500 | [diff] [blame] | 27 | #include <linux/kvm_para.h> |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 28 | #include <linux/perf_event.h> |
Ulrich Obergfell | 81a4bee | 2015-09-04 15:45:15 -0700 | [diff] [blame] | 29 | #include <linux/kthread.h> |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 30 | |
Ulrich Obergfell | 84d56e6 | 2015-04-14 15:43:55 -0700 | [diff] [blame] | 31 | /* |
| 32 | * The run state of the lockup detectors is controlled by the content of the |
| 33 | * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit - |
| 34 | * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector. |
| 35 | * |
| 36 | * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled' |
| 37 | * are variables that are only used as an 'interface' between the parameters |
| 38 | * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The |
| 39 | * 'watchdog_thresh' variable is handled differently because its value is not |
| 40 | * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh' |
| 41 | * is equal zero. |
| 42 | */ |
| 43 | #define NMI_WATCHDOG_ENABLED_BIT 0 |
| 44 | #define SOFT_WATCHDOG_ENABLED_BIT 1 |
| 45 | #define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT) |
| 46 | #define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT) |
| 47 | |
Peter Zijlstra | ab992dc | 2015-05-18 11:31:50 +0200 | [diff] [blame] | 48 | static DEFINE_MUTEX(watchdog_proc_mutex); |
| 49 | |
Ulrich Obergfell | 84d56e6 | 2015-04-14 15:43:55 -0700 | [diff] [blame] | 50 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
| 51 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED; |
| 52 | #else |
| 53 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED; |
| 54 | #endif |
| 55 | int __read_mostly nmi_watchdog_enabled; |
| 56 | int __read_mostly soft_watchdog_enabled; |
| 57 | int __read_mostly watchdog_user_enabled; |
Mandeep Singh Baines | 4eec42f | 2011-05-22 22:10:23 -0700 | [diff] [blame] | 58 | int __read_mostly watchdog_thresh = 10; |
Ulrich Obergfell | 84d56e6 | 2015-04-14 15:43:55 -0700 | [diff] [blame] | 59 | |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 60 | #ifdef CONFIG_SMP |
| 61 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; |
Jiri Kosina | 5553787 | 2015-11-05 18:44:41 -0800 | [diff] [blame] | 62 | int __read_mostly sysctl_hardlockup_all_cpu_backtrace; |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 63 | #else |
| 64 | #define sysctl_softlockup_all_cpu_backtrace 0 |
Jiri Kosina | 5553787 | 2015-11-05 18:44:41 -0800 | [diff] [blame] | 65 | #define sysctl_hardlockup_all_cpu_backtrace 0 |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 66 | #endif |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 67 | static struct cpumask watchdog_cpumask __read_mostly; |
| 68 | unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); |
| 69 | |
| 70 | /* Helper for online, unparked cpus. */ |
| 71 | #define for_each_watchdog_cpu(cpu) \ |
| 72 | for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask) |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 73 | |
Ulrich Obergfell | ec6a906 | 2015-09-04 15:45:28 -0700 | [diff] [blame] | 74 | /* |
| 75 | * The 'watchdog_running' variable is set to 1 when the watchdog threads |
| 76 | * are registered/started and is set to 0 when the watchdog threads are |
| 77 | * unregistered/stopped, so it is an indicator whether the threads exist. |
| 78 | */ |
Frederic Weisbecker | 3c00ea8 | 2013-05-19 20:45:15 +0200 | [diff] [blame] | 79 | static int __read_mostly watchdog_running; |
Ulrich Obergfell | ec6a906 | 2015-09-04 15:45:28 -0700 | [diff] [blame] | 80 | /* |
| 81 | * If a subsystem has a need to deactivate the watchdog temporarily, it |
| 82 | * can use the suspend/resume interface to achieve this. The content of |
| 83 | * the 'watchdog_suspended' variable reflects this state. Existing threads |
| 84 | * are parked/unparked by the lockup_detector_{suspend|resume} functions |
| 85 | * (see comment blocks pertaining to those functions for further details). |
| 86 | * |
| 87 | * 'watchdog_suspended' also prevents threads from being registered/started |
| 88 | * or unregistered/stopped via parameters in /proc/sys/kernel, so the state |
| 89 | * of 'watchdog_running' cannot change while the watchdog is deactivated |
| 90 | * temporarily (see related code in 'proc' handlers). |
| 91 | */ |
| 92 | static int __read_mostly watchdog_suspended; |
| 93 | |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 94 | static u64 __read_mostly sample_period; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 95 | |
| 96 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); |
| 97 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); |
| 98 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); |
Olav Haugan | d8354e6 | 2016-08-18 16:49:44 -0700 | [diff] [blame] | 99 | static DEFINE_PER_CPU(unsigned int, watchdog_en); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 100 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 101 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 102 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
| 103 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); |
chai wen | b1a8de1 | 2014-10-09 15:25:17 -0700 | [diff] [blame] | 104 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
Frederic Weisbecker | 23637d4 | 2010-05-15 23:15:20 +0200 | [diff] [blame] | 105 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Don Zickus | cafcd80 | 2010-05-14 11:11:21 -0400 | [diff] [blame] | 106 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
| 107 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 108 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 109 | #endif |
| 110 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU |
| 111 | static cpumask_t __read_mostly watchdog_cpus; |
| 112 | #endif |
| 113 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 114 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); |
| 115 | #endif |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 116 | static unsigned long soft_lockup_nmi_warn; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 117 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 118 | /* boot commands */ |
| 119 | /* |
| 120 | * Should we panic when a soft-lockup or hard-lockup occurs: |
| 121 | */ |
Frederic Weisbecker | 23637d4 | 2010-05-15 23:15:20 +0200 | [diff] [blame] | 122 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Don Zickus | ac1f591 | 2015-11-05 18:44:44 -0800 | [diff] [blame] | 123 | unsigned int __read_mostly hardlockup_panic = |
Don Zickus | fef2c9b | 2011-03-22 16:34:16 -0700 | [diff] [blame] | 124 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; |
Brian Norris | de361bf | 2016-02-29 17:42:29 -0800 | [diff] [blame] | 125 | static unsigned long __maybe_unused hardlockup_allcpu_dumped; |
Ulrich Obergfell | 6e7458a | 2014-10-13 15:55:35 -0700 | [diff] [blame] | 126 | /* |
| 127 | * We may not want to enable hard lockup detection by default in all cases, |
| 128 | * for example when running the kernel as a guest on a hypervisor. In these |
| 129 | * cases this function can be called to disable hard lockup detection. This |
| 130 | * function should only be executed once by the boot processor before the |
| 131 | * kernel command line parameters are parsed, because otherwise it is not |
| 132 | * possible to override this in hardlockup_panic_setup(). |
| 133 | */ |
Ulrich Obergfell | 692297d | 2015-04-14 15:44:19 -0700 | [diff] [blame] | 134 | void hardlockup_detector_disable(void) |
Ulrich Obergfell | 6e7458a | 2014-10-13 15:55:35 -0700 | [diff] [blame] | 135 | { |
Ulrich Obergfell | 692297d | 2015-04-14 15:44:19 -0700 | [diff] [blame] | 136 | watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; |
Ulrich Obergfell | 6e7458a | 2014-10-13 15:55:35 -0700 | [diff] [blame] | 137 | } |
| 138 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 139 | static int __init hardlockup_panic_setup(char *str) |
| 140 | { |
| 141 | if (!strncmp(str, "panic", 5)) |
| 142 | hardlockup_panic = 1; |
Don Zickus | fef2c9b | 2011-03-22 16:34:16 -0700 | [diff] [blame] | 143 | else if (!strncmp(str, "nopanic", 7)) |
| 144 | hardlockup_panic = 0; |
Don Zickus | 5dc3055 | 2010-11-29 17:07:17 -0500 | [diff] [blame] | 145 | else if (!strncmp(str, "0", 1)) |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 146 | watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; |
| 147 | else if (!strncmp(str, "1", 1)) |
| 148 | watchdog_enabled |= NMI_WATCHDOG_ENABLED; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 149 | return 1; |
| 150 | } |
| 151 | __setup("nmi_watchdog=", hardlockup_panic_setup); |
| 152 | #endif |
| 153 | |
| 154 | unsigned int __read_mostly softlockup_panic = |
| 155 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; |
| 156 | |
| 157 | static int __init softlockup_panic_setup(char *str) |
| 158 | { |
| 159 | softlockup_panic = simple_strtoul(str, NULL, 0); |
| 160 | |
| 161 | return 1; |
| 162 | } |
| 163 | __setup("softlockup_panic=", softlockup_panic_setup); |
| 164 | |
| 165 | static int __init nowatchdog_setup(char *str) |
| 166 | { |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 167 | watchdog_enabled = 0; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 168 | return 1; |
| 169 | } |
| 170 | __setup("nowatchdog", nowatchdog_setup); |
| 171 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 172 | static int __init nosoftlockup_setup(char *str) |
| 173 | { |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 174 | watchdog_enabled &= ~SOFT_WATCHDOG_ENABLED; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 175 | return 1; |
| 176 | } |
| 177 | __setup("nosoftlockup", nosoftlockup_setup); |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 178 | |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 179 | #ifdef CONFIG_SMP |
| 180 | static int __init softlockup_all_cpu_backtrace_setup(char *str) |
| 181 | { |
| 182 | sysctl_softlockup_all_cpu_backtrace = |
| 183 | !!simple_strtol(str, NULL, 0); |
| 184 | return 1; |
| 185 | } |
| 186 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); |
Jiri Kosina | 5553787 | 2015-11-05 18:44:41 -0800 | [diff] [blame] | 187 | static int __init hardlockup_all_cpu_backtrace_setup(char *str) |
| 188 | { |
| 189 | sysctl_hardlockup_all_cpu_backtrace = |
| 190 | !!simple_strtol(str, NULL, 0); |
| 191 | return 1; |
| 192 | } |
| 193 | __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup); |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 194 | #endif |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 195 | |
Mandeep Singh Baines | 4eec42f | 2011-05-22 22:10:23 -0700 | [diff] [blame] | 196 | /* |
| 197 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- |
| 198 | * lockups can have false positives under extreme conditions. So we generally |
| 199 | * want a higher threshold for soft lockups than for hard lockups. So we couple |
| 200 | * the thresholds with a factor: we make the soft threshold twice the amount of |
| 201 | * time the hard threshold is. |
| 202 | */ |
Ingo Molnar | 6e9101a | 2011-05-24 05:43:18 +0200 | [diff] [blame] | 203 | static int get_softlockup_thresh(void) |
Mandeep Singh Baines | 4eec42f | 2011-05-22 22:10:23 -0700 | [diff] [blame] | 204 | { |
| 205 | return watchdog_thresh * 2; |
| 206 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 207 | |
| 208 | /* |
| 209 | * Returns seconds, approximately. We don't need nanosecond |
| 210 | * resolution, and we don't need to waste time with a big divide when |
| 211 | * 2^30ns == 1.074s. |
| 212 | */ |
Namhyung Kim | c06b4f1 | 2012-12-27 11:49:44 +0900 | [diff] [blame] | 213 | static unsigned long get_timestamp(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 214 | { |
Cyril Bur | 545a2bf | 2015-02-12 15:01:24 -0800 | [diff] [blame] | 215 | return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 216 | } |
| 217 | |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 218 | static void set_sample_period(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 219 | { |
| 220 | /* |
Mandeep Singh Baines | 586692a | 2011-05-22 22:10:22 -0700 | [diff] [blame] | 221 | * convert watchdog_thresh from seconds to ns |
Fernando Luis Vázquez Cao | 86f5e6a | 2012-02-09 17:42:22 -0500 | [diff] [blame] | 222 | * the divide by 5 is to give hrtimer several chances (two |
| 223 | * or three with the current relation between the soft |
| 224 | * and hard thresholds) to increment before the |
| 225 | * hardlockup detector generates a warning |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 226 | */ |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 227 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 228 | } |
| 229 | |
| 230 | /* Commands for resetting the watchdog */ |
| 231 | static void __touch_watchdog(void) |
| 232 | { |
Namhyung Kim | c06b4f1 | 2012-12-27 11:49:44 +0900 | [diff] [blame] | 233 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 234 | } |
| 235 | |
Tejun Heo | 03e0d46 | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 236 | /** |
| 237 | * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls |
| 238 | * |
| 239 | * Call when the scheduler may have stalled for legitimate reasons |
| 240 | * preventing the watchdog task from executing - e.g. the scheduler |
| 241 | * entering idle state. This should only be used for scheduler events. |
| 242 | * Use touch_softlockup_watchdog() for everything else. |
| 243 | */ |
| 244 | void touch_softlockup_watchdog_sched(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 245 | { |
Andrew Morton | 7861144 | 2014-04-18 15:07:12 -0700 | [diff] [blame] | 246 | /* |
| 247 | * Preemption can be enabled. It doesn't matter which CPU's timestamp |
| 248 | * gets zeroed here, so use the raw_ operation. |
| 249 | */ |
| 250 | raw_cpu_write(watchdog_touch_ts, 0); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 251 | } |
Tejun Heo | 03e0d46 | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 252 | |
| 253 | void touch_softlockup_watchdog(void) |
| 254 | { |
| 255 | touch_softlockup_watchdog_sched(); |
Tejun Heo | 82607adc | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 256 | wq_watchdog_touch(raw_smp_processor_id()); |
Tejun Heo | 03e0d46 | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 257 | } |
Ingo Molnar | 0167c78 | 2010-05-13 08:53:33 +0200 | [diff] [blame] | 258 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 259 | |
Don Zickus | 332fbdb | 2010-05-07 17:11:45 -0400 | [diff] [blame] | 260 | void touch_all_softlockup_watchdogs(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 261 | { |
| 262 | int cpu; |
| 263 | |
| 264 | /* |
| 265 | * this is done lockless |
| 266 | * do we care if a 0 races with a timestamp? |
| 267 | * all it means is the softlock check starts one cycle later |
| 268 | */ |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 269 | for_each_watchdog_cpu(cpu) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 270 | per_cpu(watchdog_touch_ts, cpu) = 0; |
Tejun Heo | 82607adc | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 271 | wq_watchdog_touch(-1); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 272 | } |
| 273 | |
Don Zickus | cafcd80 | 2010-05-14 11:11:21 -0400 | [diff] [blame] | 274 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 275 | void touch_nmi_watchdog(void) |
| 276 | { |
Ben Zhang | 62572e2 | 2014-04-03 14:47:18 -0700 | [diff] [blame] | 277 | /* |
| 278 | * Using __raw here because some code paths have |
| 279 | * preemption enabled. If preemption is enabled |
| 280 | * then interrupts should be enabled too, in which |
| 281 | * case we shouldn't have to worry about the watchdog |
| 282 | * going off. |
| 283 | */ |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 284 | raw_cpu_write(watchdog_nmi_touch, true); |
Don Zickus | 332fbdb | 2010-05-07 17:11:45 -0400 | [diff] [blame] | 285 | touch_softlockup_watchdog(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 286 | } |
| 287 | EXPORT_SYMBOL(touch_nmi_watchdog); |
| 288 | |
Don Zickus | cafcd80 | 2010-05-14 11:11:21 -0400 | [diff] [blame] | 289 | #endif |
| 290 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 291 | void touch_softlockup_watchdog_sync(void) |
| 292 | { |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 293 | __this_cpu_write(softlockup_touch_sync, true); |
| 294 | __this_cpu_write(watchdog_touch_ts, 0); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 295 | } |
| 296 | |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 297 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 298 | /* watchdog detector functions */ |
Yaowei Bai | 451637e | 2015-11-05 18:44:24 -0800 | [diff] [blame] | 299 | static bool is_hardlockup(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 300 | { |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 301 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 302 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 303 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
Yaowei Bai | 451637e | 2015-11-05 18:44:24 -0800 | [diff] [blame] | 304 | return true; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 305 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 306 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
Yaowei Bai | 451637e | 2015-11-05 18:44:24 -0800 | [diff] [blame] | 307 | return false; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 308 | } |
| 309 | #endif |
| 310 | |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 311 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU |
| 312 | static unsigned int watchdog_next_cpu(unsigned int cpu) |
| 313 | { |
| 314 | cpumask_t cpus = watchdog_cpus; |
| 315 | unsigned int next_cpu; |
| 316 | |
| 317 | next_cpu = cpumask_next(cpu, &cpus); |
| 318 | if (next_cpu >= nr_cpu_ids) |
| 319 | next_cpu = cpumask_first(&cpus); |
| 320 | |
| 321 | if (next_cpu == cpu) |
| 322 | return nr_cpu_ids; |
| 323 | |
| 324 | return next_cpu; |
| 325 | } |
| 326 | |
| 327 | static int is_hardlockup_other_cpu(unsigned int cpu) |
| 328 | { |
| 329 | unsigned long hrint = per_cpu(hrtimer_interrupts, cpu); |
| 330 | |
| 331 | if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint) |
| 332 | return 1; |
| 333 | |
| 334 | per_cpu(hrtimer_interrupts_saved, cpu) = hrint; |
| 335 | return 0; |
| 336 | } |
| 337 | |
| 338 | static void watchdog_check_hardlockup_other_cpu(void) |
| 339 | { |
| 340 | unsigned int next_cpu; |
| 341 | |
| 342 | /* |
| 343 | * Test for hardlockups every 3 samples. The sample period is |
| 344 | * watchdog_thresh * 2 / 5, so 3 samples gets us back to slightly over |
| 345 | * watchdog_thresh (over by 20%). |
| 346 | */ |
| 347 | if (__this_cpu_read(hrtimer_interrupts) % 3 != 0) |
| 348 | return; |
| 349 | |
| 350 | /* check for a hardlockup on the next cpu */ |
| 351 | next_cpu = watchdog_next_cpu(smp_processor_id()); |
| 352 | if (next_cpu >= nr_cpu_ids) |
| 353 | return; |
| 354 | |
| 355 | smp_rmb(); |
| 356 | |
| 357 | if (per_cpu(watchdog_nmi_touch, next_cpu) == true) { |
| 358 | per_cpu(watchdog_nmi_touch, next_cpu) = false; |
| 359 | return; |
| 360 | } |
| 361 | |
| 362 | if (is_hardlockup_other_cpu(next_cpu)) { |
| 363 | /* only warn once */ |
| 364 | if (per_cpu(hard_watchdog_warn, next_cpu) == true) |
| 365 | return; |
| 366 | |
| 367 | if (hardlockup_panic) |
| 368 | panic("Watchdog detected hard LOCKUP on cpu %u", next_cpu); |
| 369 | else |
| 370 | WARN(1, "Watchdog detected hard LOCKUP on cpu %u", next_cpu); |
| 371 | |
| 372 | per_cpu(hard_watchdog_warn, next_cpu) = true; |
| 373 | } else { |
| 374 | per_cpu(hard_watchdog_warn, next_cpu) = false; |
| 375 | } |
| 376 | } |
| 377 | #else |
| 378 | static inline void watchdog_check_hardlockup_other_cpu(void) { return; } |
| 379 | #endif |
| 380 | |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 381 | static int is_softlockup(unsigned long touch_ts) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 382 | { |
Namhyung Kim | c06b4f1 | 2012-12-27 11:49:44 +0900 | [diff] [blame] | 383 | unsigned long now = get_timestamp(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 384 | |
Ulrich Obergfell | 39d2da2 | 2015-11-05 18:44:56 -0800 | [diff] [blame] | 385 | if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){ |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 386 | /* Warn about unreasonable delays. */ |
| 387 | if (time_after(now, touch_ts + get_softlockup_thresh())) |
| 388 | return now - touch_ts; |
| 389 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 390 | return 0; |
| 391 | } |
| 392 | |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 393 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI |
Cyrill Gorcunov | 1880c4a | 2011-06-23 16:49:18 +0400 | [diff] [blame] | 394 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 395 | static struct perf_event_attr wd_hw_attr = { |
| 396 | .type = PERF_TYPE_HARDWARE, |
| 397 | .config = PERF_COUNT_HW_CPU_CYCLES, |
| 398 | .size = sizeof(struct perf_event_attr), |
| 399 | .pinned = 1, |
| 400 | .disabled = 1, |
| 401 | }; |
| 402 | |
| 403 | /* Callback function for perf event subsystem */ |
Peter Zijlstra | a8b0ca1 | 2011-06-27 14:41:57 +0200 | [diff] [blame] | 404 | static void watchdog_overflow_callback(struct perf_event *event, |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 405 | struct perf_sample_data *data, |
| 406 | struct pt_regs *regs) |
| 407 | { |
Peter Zijlstra | c6db67c | 2010-08-20 11:49:15 +0200 | [diff] [blame] | 408 | /* Ensure the watchdog never gets throttled */ |
| 409 | event->hw.interrupts = 0; |
| 410 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 411 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
| 412 | __this_cpu_write(watchdog_nmi_touch, false); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 413 | return; |
| 414 | } |
| 415 | |
| 416 | /* check for a hardlockup |
| 417 | * This is done by making sure our timer interrupt |
| 418 | * is incrementing. The timer interrupt should have |
| 419 | * fired multiple times before we overflow'd. If it hasn't |
| 420 | * then this is a good indication the cpu is stuck |
| 421 | */ |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 422 | if (is_hardlockup()) { |
| 423 | int this_cpu = smp_processor_id(); |
Jiri Kosina | 5553787 | 2015-11-05 18:44:41 -0800 | [diff] [blame] | 424 | struct pt_regs *regs = get_irq_regs(); |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 425 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 426 | /* only print hardlockups once */ |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 427 | if (__this_cpu_read(hard_watchdog_warn) == true) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 428 | return; |
| 429 | |
Jiri Kosina | 5553787 | 2015-11-05 18:44:41 -0800 | [diff] [blame] | 430 | pr_emerg("Watchdog detected hard LOCKUP on cpu %d", this_cpu); |
| 431 | print_modules(); |
| 432 | print_irqtrace_events(current); |
| 433 | if (regs) |
| 434 | show_regs(regs); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 435 | else |
Jiri Kosina | 5553787 | 2015-11-05 18:44:41 -0800 | [diff] [blame] | 436 | dump_stack(); |
| 437 | |
| 438 | /* |
| 439 | * Perform all-CPU dump only once to avoid multiple hardlockups |
| 440 | * generating interleaving traces |
| 441 | */ |
| 442 | if (sysctl_hardlockup_all_cpu_backtrace && |
| 443 | !test_and_set_bit(0, &hardlockup_allcpu_dumped)) |
| 444 | trigger_allbutself_cpu_backtrace(); |
| 445 | |
| 446 | if (hardlockup_panic) |
Hidehiro Kawai | 58c5661 | 2015-12-14 11:19:10 +0100 | [diff] [blame] | 447 | nmi_panic(regs, "Hard LOCKUP"); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 448 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 449 | __this_cpu_write(hard_watchdog_warn, true); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 450 | return; |
| 451 | } |
| 452 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 453 | __this_cpu_write(hard_watchdog_warn, false); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 454 | return; |
| 455 | } |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 456 | #endif /* CONFIG_HARDLOCKUP_DETECTOR_NMI */ |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 457 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 458 | static void watchdog_interrupt_count(void) |
| 459 | { |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 460 | __this_cpu_inc(hrtimer_interrupts); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 461 | } |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 462 | |
| 463 | static int watchdog_nmi_enable(unsigned int cpu); |
| 464 | static void watchdog_nmi_disable(unsigned int cpu); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 465 | |
Ulrich Obergfell | 58cf690 | 2015-11-05 18:44:30 -0800 | [diff] [blame] | 466 | static int watchdog_enable_all_cpus(void); |
| 467 | static void watchdog_disable_all_cpus(void); |
| 468 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 469 | /* watchdog kicker functions */ |
| 470 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) |
| 471 | { |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 472 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 473 | struct pt_regs *regs = get_irq_regs(); |
| 474 | int duration; |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 475 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 476 | |
| 477 | /* kick the hardlockup detector */ |
| 478 | watchdog_interrupt_count(); |
| 479 | |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 480 | /* test for hardlockups on the next cpu */ |
| 481 | watchdog_check_hardlockup_other_cpu(); |
| 482 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 483 | /* kick the softlockup detector */ |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 484 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 485 | |
| 486 | /* .. and repeat */ |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 487 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 488 | |
| 489 | if (touch_ts == 0) { |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 490 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 491 | /* |
| 492 | * If the time stamp was touched atomically |
| 493 | * make sure the scheduler tick is up to date. |
| 494 | */ |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 495 | __this_cpu_write(softlockup_touch_sync, false); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 496 | sched_clock_tick(); |
| 497 | } |
Eric B Munson | 5d1c0f4 | 2012-03-10 14:37:28 -0500 | [diff] [blame] | 498 | |
| 499 | /* Clear the guest paused flag on watchdog reset */ |
| 500 | kvm_check_and_clear_guest_paused(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 501 | __touch_watchdog(); |
| 502 | return HRTIMER_RESTART; |
| 503 | } |
| 504 | |
| 505 | /* check for a softlockup |
| 506 | * This is done by making sure a high priority task is |
| 507 | * being scheduled. The task touches the watchdog to |
| 508 | * indicate it is getting cpu time. If it hasn't then |
| 509 | * this is a good indication some task is hogging the cpu |
| 510 | */ |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 511 | duration = is_softlockup(touch_ts); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 512 | if (unlikely(duration)) { |
Eric B Munson | 5d1c0f4 | 2012-03-10 14:37:28 -0500 | [diff] [blame] | 513 | /* |
| 514 | * If a virtual machine is stopped by the host it can look to |
| 515 | * the watchdog like a soft lockup, check to see if the host |
| 516 | * stopped the vm before we issue the warning |
| 517 | */ |
| 518 | if (kvm_check_and_clear_guest_paused()) |
| 519 | return HRTIMER_RESTART; |
| 520 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 521 | /* only warn once */ |
chai wen | b1a8de1 | 2014-10-09 15:25:17 -0700 | [diff] [blame] | 522 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
| 523 | /* |
| 524 | * When multiple processes are causing softlockups the |
| 525 | * softlockup detector only warns on the first one |
| 526 | * because the code relies on a full quiet cycle to |
| 527 | * re-arm. The second process prevents the quiet cycle |
| 528 | * and never gets reported. Use task pointers to detect |
| 529 | * this. |
| 530 | */ |
| 531 | if (__this_cpu_read(softlockup_task_ptr_saved) != |
| 532 | current) { |
| 533 | __this_cpu_write(soft_watchdog_warn, false); |
| 534 | __touch_watchdog(); |
| 535 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 536 | return HRTIMER_RESTART; |
chai wen | b1a8de1 | 2014-10-09 15:25:17 -0700 | [diff] [blame] | 537 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 538 | |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 539 | if (softlockup_all_cpu_backtrace) { |
| 540 | /* Prevent multiple soft-lockup reports if one cpu is already |
| 541 | * engaged in dumping cpu back traces |
| 542 | */ |
| 543 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { |
| 544 | /* Someone else will report us. Let's give up */ |
| 545 | __this_cpu_write(soft_watchdog_warn, true); |
| 546 | return HRTIMER_RESTART; |
| 547 | } |
| 548 | } |
| 549 | |
Fabian Frederick | 656c3b7 | 2014-08-06 16:04:03 -0700 | [diff] [blame] | 550 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 551 | smp_processor_id(), duration, |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 552 | current->comm, task_pid_nr(current)); |
chai wen | b1a8de1 | 2014-10-09 15:25:17 -0700 | [diff] [blame] | 553 | __this_cpu_write(softlockup_task_ptr_saved, current); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 554 | print_modules(); |
| 555 | print_irqtrace_events(current); |
| 556 | if (regs) |
| 557 | show_regs(regs); |
| 558 | else |
| 559 | dump_stack(); |
| 560 | |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 561 | if (softlockup_all_cpu_backtrace) { |
| 562 | /* Avoid generating two back traces for current |
| 563 | * given that one is already made above |
| 564 | */ |
| 565 | trigger_allbutself_cpu_backtrace(); |
| 566 | |
| 567 | clear_bit(0, &soft_lockup_nmi_warn); |
| 568 | /* Barrier to sync with other cpus */ |
| 569 | smp_mb__after_atomic(); |
| 570 | } |
| 571 | |
Josh Hunt | 69361ee | 2014-08-08 14:22:31 -0700 | [diff] [blame] | 572 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 573 | if (softlockup_panic) |
| 574 | panic("softlockup: hung tasks"); |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 575 | __this_cpu_write(soft_watchdog_warn, true); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 576 | } else |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 577 | __this_cpu_write(soft_watchdog_warn, false); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 578 | |
| 579 | return HRTIMER_RESTART; |
| 580 | } |
| 581 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 582 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 583 | { |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 584 | struct sched_param param = { .sched_priority = prio }; |
| 585 | |
| 586 | sched_setscheduler(current, policy, ¶m); |
| 587 | } |
| 588 | |
Olav Haugan | d8354e6 | 2016-08-18 16:49:44 -0700 | [diff] [blame] | 589 | /* Must be called with hotplug lock (lock_device_hotplug()) held. */ |
| 590 | void watchdog_enable(unsigned int cpu) |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 591 | { |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 592 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
Olav Haugan | d8354e6 | 2016-08-18 16:49:44 -0700 | [diff] [blame] | 593 | unsigned int *enabled = raw_cpu_ptr(&watchdog_en); |
| 594 | |
| 595 | lock_device_hotplug_assert(); |
| 596 | |
| 597 | if (*enabled) |
| 598 | return; |
| 599 | *enabled = 1; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 600 | |
Bjørn Mork | 3935e895 | 2012-12-19 20:51:31 +0100 | [diff] [blame] | 601 | /* kick off the timer for the hardlockup detector */ |
| 602 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| 603 | hrtimer->function = watchdog_timer_fn; |
| 604 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 605 | /* Enable the perf event */ |
| 606 | watchdog_nmi_enable(cpu); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 607 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 608 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 609 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 610 | HRTIMER_MODE_REL_PINNED); |
| 611 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 612 | /* initialize timestamp */ |
| 613 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); |
| 614 | __touch_watchdog(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 615 | } |
| 616 | |
Olav Haugan | d8354e6 | 2016-08-18 16:49:44 -0700 | [diff] [blame] | 617 | /* Must be called with hotplug lock (lock_device_hotplug()) held. */ |
| 618 | void watchdog_disable(unsigned int cpu) |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 619 | { |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 620 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
Olav Haugan | d8354e6 | 2016-08-18 16:49:44 -0700 | [diff] [blame] | 621 | unsigned int *enabled = raw_cpu_ptr(&watchdog_en); |
| 622 | |
| 623 | lock_device_hotplug_assert(); |
| 624 | |
| 625 | if (!*enabled) |
| 626 | return; |
| 627 | *enabled = 0; |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 628 | |
| 629 | watchdog_set_prio(SCHED_NORMAL, 0); |
| 630 | hrtimer_cancel(hrtimer); |
| 631 | /* disable the perf event */ |
| 632 | watchdog_nmi_disable(cpu); |
| 633 | } |
| 634 | |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 635 | static void watchdog_cleanup(unsigned int cpu, bool online) |
| 636 | { |
| 637 | watchdog_disable(cpu); |
| 638 | } |
| 639 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 640 | static int watchdog_should_run(unsigned int cpu) |
| 641 | { |
| 642 | return __this_cpu_read(hrtimer_interrupts) != |
| 643 | __this_cpu_read(soft_lockup_hrtimer_cnt); |
| 644 | } |
| 645 | |
| 646 | /* |
| 647 | * The watchdog thread function - touches the timestamp. |
| 648 | * |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 649 | * It only runs once every sample_period seconds (4 seconds by |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 650 | * default) to reset the softlockup timestamp. If this gets delayed |
| 651 | * for more than 2*watchdog_thresh seconds then the debug-printout |
| 652 | * triggers in watchdog_timer_fn(). |
| 653 | */ |
| 654 | static void watchdog(unsigned int cpu) |
| 655 | { |
| 656 | __this_cpu_write(soft_lockup_hrtimer_cnt, |
| 657 | __this_cpu_read(hrtimer_interrupts)); |
| 658 | __touch_watchdog(); |
Ulrich Obergfell | bcfba4f | 2015-04-14 15:44:10 -0700 | [diff] [blame] | 659 | |
| 660 | /* |
| 661 | * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the |
| 662 | * failure path. Check for failures that can occur asynchronously - |
| 663 | * for example, when CPUs are on-lined - and shut down the hardware |
| 664 | * perf event on each CPU accordingly. |
| 665 | * |
| 666 | * The only non-obvious place this bit can be cleared is through |
| 667 | * watchdog_nmi_enable(), so a pr_info() is placed there. Placing a |
| 668 | * pr_info here would be too noisy as it would result in a message |
| 669 | * every few seconds if the hardlockup was disabled but the softlockup |
| 670 | * enabled. |
| 671 | */ |
| 672 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) |
| 673 | watchdog_nmi_disable(cpu); |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 674 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 675 | |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 676 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_NMI |
Don Zickus | a702704 | 2012-06-13 09:35:48 -0400 | [diff] [blame] | 677 | /* |
| 678 | * People like the simple clean cpu node info on boot. |
| 679 | * Reduce the watchdog noise by only printing messages |
| 680 | * that are different from what cpu0 displayed. |
| 681 | */ |
| 682 | static unsigned long cpu0_err; |
| 683 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 684 | static int watchdog_nmi_enable(unsigned int cpu) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 685 | { |
| 686 | struct perf_event_attr *wd_attr; |
| 687 | struct perf_event *event = per_cpu(watchdog_ev, cpu); |
| 688 | |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 689 | /* nothing to do if the hard lockup detector is disabled */ |
| 690 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) |
| 691 | goto out; |
Ulrich Obergfell | 6e7458a | 2014-10-13 15:55:35 -0700 | [diff] [blame] | 692 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 693 | /* is it already setup and enabled? */ |
| 694 | if (event && event->state > PERF_EVENT_STATE_OFF) |
| 695 | goto out; |
| 696 | |
| 697 | /* it is setup but not enabled */ |
| 698 | if (event != NULL) |
| 699 | goto out_enable; |
| 700 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 701 | wd_attr = &wd_hw_attr; |
Mandeep Singh Baines | 4eec42f | 2011-05-22 22:10:23 -0700 | [diff] [blame] | 702 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
Cyrill Gorcunov | 1880c4a | 2011-06-23 16:49:18 +0400 | [diff] [blame] | 703 | |
| 704 | /* Try to register using hardware perf events */ |
Avi Kivity | 4dc0da8 | 2011-06-29 18:42:35 +0300 | [diff] [blame] | 705 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
Don Zickus | a702704 | 2012-06-13 09:35:48 -0400 | [diff] [blame] | 706 | |
| 707 | /* save cpu0 error for future comparision */ |
| 708 | if (cpu == 0 && IS_ERR(event)) |
| 709 | cpu0_err = PTR_ERR(event); |
| 710 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 711 | if (!IS_ERR(event)) { |
Don Zickus | a702704 | 2012-06-13 09:35:48 -0400 | [diff] [blame] | 712 | /* only print for cpu0 or different than cpu0 */ |
| 713 | if (cpu == 0 || cpu0_err) |
| 714 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 715 | goto out_save; |
| 716 | } |
| 717 | |
Ulrich Obergfell | bcfba4f | 2015-04-14 15:44:10 -0700 | [diff] [blame] | 718 | /* |
| 719 | * Disable the hard lockup detector if _any_ CPU fails to set up |
| 720 | * set up the hardware perf event. The watchdog() function checks |
| 721 | * the NMI_WATCHDOG_ENABLED bit periodically. |
| 722 | * |
| 723 | * The barriers are for syncing up watchdog_enabled across all the |
| 724 | * cpus, as clear_bit() does not use barriers. |
| 725 | */ |
| 726 | smp_mb__before_atomic(); |
| 727 | clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled); |
| 728 | smp_mb__after_atomic(); |
| 729 | |
Don Zickus | a702704 | 2012-06-13 09:35:48 -0400 | [diff] [blame] | 730 | /* skip displaying the same error again */ |
| 731 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) |
| 732 | return PTR_ERR(event); |
Don Zickus | 5651f7f | 2011-02-09 14:02:33 -0500 | [diff] [blame] | 733 | |
| 734 | /* vary the KERN level based on the returned errno */ |
| 735 | if (PTR_ERR(event) == -EOPNOTSUPP) |
Andrew Morton | 4501980 | 2012-03-23 15:01:55 -0700 | [diff] [blame] | 736 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
Don Zickus | 5651f7f | 2011-02-09 14:02:33 -0500 | [diff] [blame] | 737 | else if (PTR_ERR(event) == -ENOENT) |
Fabian Frederick | 656c3b7 | 2014-08-06 16:04:03 -0700 | [diff] [blame] | 738 | pr_warn("disabled (cpu%i): hardware events not enabled\n", |
Andrew Morton | 4501980 | 2012-03-23 15:01:55 -0700 | [diff] [blame] | 739 | cpu); |
Don Zickus | 5651f7f | 2011-02-09 14:02:33 -0500 | [diff] [blame] | 740 | else |
Andrew Morton | 4501980 | 2012-03-23 15:01:55 -0700 | [diff] [blame] | 741 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
| 742 | cpu, PTR_ERR(event)); |
Ulrich Obergfell | bcfba4f | 2015-04-14 15:44:10 -0700 | [diff] [blame] | 743 | |
| 744 | pr_info("Shutting down hard lockup detector on all cpus\n"); |
| 745 | |
Akinobu Mita | eac2433 | 2010-08-31 23:00:08 -0400 | [diff] [blame] | 746 | return PTR_ERR(event); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 747 | |
| 748 | /* success path */ |
| 749 | out_save: |
| 750 | per_cpu(watchdog_ev, cpu) = event; |
| 751 | out_enable: |
| 752 | perf_event_enable(per_cpu(watchdog_ev, cpu)); |
| 753 | out: |
| 754 | return 0; |
| 755 | } |
| 756 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 757 | static void watchdog_nmi_disable(unsigned int cpu) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 758 | { |
| 759 | struct perf_event *event = per_cpu(watchdog_ev, cpu); |
| 760 | |
| 761 | if (event) { |
| 762 | perf_event_disable(event); |
| 763 | per_cpu(watchdog_ev, cpu) = NULL; |
| 764 | |
| 765 | /* should be in cleanup, but blocks oprofile */ |
| 766 | perf_event_release_kernel(event); |
| 767 | } |
Ulrich Obergfell | df57714 | 2014-08-11 10:49:25 -0400 | [diff] [blame] | 768 | if (cpu == 0) { |
| 769 | /* watchdog_nmi_enable() expects this to be zero initially. */ |
| 770 | cpu0_err = 0; |
| 771 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 772 | } |
Stephane Eranian | b3738d2 | 2014-11-17 20:07:03 +0100 | [diff] [blame] | 773 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 774 | #else |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 775 | #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU |
| 776 | static int watchdog_nmi_enable(unsigned int cpu) |
| 777 | { |
| 778 | /* |
| 779 | * The new cpu will be marked online before the first hrtimer interrupt |
| 780 | * runs on it. If another cpu tests for a hardlockup on the new cpu |
| 781 | * before it has run its first hrtimer, it will get a false positive. |
| 782 | * Touch the watchdog on the new cpu to delay the first check for at |
| 783 | * least 3 sampling periods to guarantee one hrtimer has run on the new |
| 784 | * cpu. |
| 785 | */ |
| 786 | per_cpu(watchdog_nmi_touch, cpu) = true; |
| 787 | smp_wmb(); |
| 788 | cpumask_set_cpu(cpu, &watchdog_cpus); |
| 789 | return 0; |
| 790 | } |
| 791 | |
| 792 | static void watchdog_nmi_disable(unsigned int cpu) |
| 793 | { |
| 794 | unsigned int next_cpu = watchdog_next_cpu(cpu); |
| 795 | |
| 796 | /* |
| 797 | * Offlining this cpu will cause the cpu before this one to start |
| 798 | * checking the one after this one. If this cpu just finished checking |
| 799 | * the next cpu and updating hrtimer_interrupts_saved, and then the |
| 800 | * previous cpu checks it within one sample period, it will trigger a |
| 801 | * false positive. Touch the watchdog on the next cpu to prevent it. |
| 802 | */ |
| 803 | if (next_cpu < nr_cpu_ids) |
| 804 | per_cpu(watchdog_nmi_touch, next_cpu) = true; |
| 805 | smp_wmb(); |
| 806 | cpumask_clear_cpu(cpu, &watchdog_cpus); |
| 807 | } |
| 808 | #else |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 809 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
| 810 | static void watchdog_nmi_disable(unsigned int cpu) { return; } |
Colin Cross | b9180a4 | 2013-01-11 13:51:48 -0800 | [diff] [blame] | 811 | #endif /* CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU */ |
| 812 | #endif /* CONFIG_HARDLOCKUP_DETECTOR_NMI */ |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 813 | |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 814 | static struct smp_hotplug_thread watchdog_threads = { |
| 815 | .store = &softlockup_watchdog, |
| 816 | .thread_should_run = watchdog_should_run, |
| 817 | .thread_fn = watchdog, |
| 818 | .thread_comm = "watchdog/%u", |
| 819 | .setup = watchdog_enable, |
| 820 | .cleanup = watchdog_cleanup, |
| 821 | .park = watchdog_disable, |
| 822 | .unpark = watchdog_enable, |
| 823 | }; |
| 824 | |
Ulrich Obergfell | 81a4bee | 2015-09-04 15:45:15 -0700 | [diff] [blame] | 825 | /* |
| 826 | * park all watchdog threads that are specified in 'watchdog_cpumask' |
Ulrich Obergfell | ee7fed5 | 2015-11-05 18:44:39 -0800 | [diff] [blame] | 827 | * |
| 828 | * This function returns an error if kthread_park() of a watchdog thread |
| 829 | * fails. In this situation, the watchdog threads of some CPUs can already |
| 830 | * be parked and the watchdog threads of other CPUs can still be runnable. |
| 831 | * Callers are expected to handle this special condition as appropriate in |
| 832 | * their context. |
Ulrich Obergfell | a2a45b8 | 2015-11-05 18:44:53 -0800 | [diff] [blame] | 833 | * |
| 834 | * This function may only be called in a context that is protected against |
| 835 | * races with CPU hotplug - for example, via get_online_cpus(). |
Ulrich Obergfell | 81a4bee | 2015-09-04 15:45:15 -0700 | [diff] [blame] | 836 | */ |
| 837 | static int watchdog_park_threads(void) |
| 838 | { |
| 839 | int cpu, ret = 0; |
| 840 | |
Ulrich Obergfell | 81a4bee | 2015-09-04 15:45:15 -0700 | [diff] [blame] | 841 | for_each_watchdog_cpu(cpu) { |
| 842 | ret = kthread_park(per_cpu(softlockup_watchdog, cpu)); |
| 843 | if (ret) |
| 844 | break; |
| 845 | } |
Ulrich Obergfell | 81a4bee | 2015-09-04 15:45:15 -0700 | [diff] [blame] | 846 | |
| 847 | return ret; |
| 848 | } |
| 849 | |
| 850 | /* |
| 851 | * unpark all watchdog threads that are specified in 'watchdog_cpumask' |
Ulrich Obergfell | a2a45b8 | 2015-11-05 18:44:53 -0800 | [diff] [blame] | 852 | * |
| 853 | * This function may only be called in a context that is protected against |
| 854 | * races with CPU hotplug - for example, via get_online_cpus(). |
Ulrich Obergfell | 81a4bee | 2015-09-04 15:45:15 -0700 | [diff] [blame] | 855 | */ |
| 856 | static void watchdog_unpark_threads(void) |
| 857 | { |
| 858 | int cpu; |
| 859 | |
Ulrich Obergfell | 81a4bee | 2015-09-04 15:45:15 -0700 | [diff] [blame] | 860 | for_each_watchdog_cpu(cpu) |
| 861 | kthread_unpark(per_cpu(softlockup_watchdog, cpu)); |
Ulrich Obergfell | 81a4bee | 2015-09-04 15:45:15 -0700 | [diff] [blame] | 862 | } |
| 863 | |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 864 | /* |
| 865 | * Suspend the hard and soft lockup detector by parking the watchdog threads. |
| 866 | */ |
Ulrich Obergfell | ec6a906 | 2015-09-04 15:45:28 -0700 | [diff] [blame] | 867 | int lockup_detector_suspend(void) |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 868 | { |
| 869 | int ret = 0; |
| 870 | |
Ulrich Obergfell | ee89e71 | 2015-11-05 18:44:47 -0800 | [diff] [blame] | 871 | get_online_cpus(); |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 872 | mutex_lock(&watchdog_proc_mutex); |
| 873 | /* |
| 874 | * Multiple suspend requests can be active in parallel (counted by |
| 875 | * the 'watchdog_suspended' variable). If the watchdog threads are |
| 876 | * running, the first caller takes care that they will be parked. |
| 877 | * The state of 'watchdog_running' cannot change while a suspend |
Ulrich Obergfell | ec6a906 | 2015-09-04 15:45:28 -0700 | [diff] [blame] | 878 | * request is active (see related code in 'proc' handlers). |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 879 | */ |
| 880 | if (watchdog_running && !watchdog_suspended) |
| 881 | ret = watchdog_park_threads(); |
| 882 | |
| 883 | if (ret == 0) |
| 884 | watchdog_suspended++; |
Ulrich Obergfell | c993590 | 2015-11-05 18:44:36 -0800 | [diff] [blame] | 885 | else { |
| 886 | watchdog_disable_all_cpus(); |
| 887 | pr_err("Failed to suspend lockup detectors, disabled\n"); |
| 888 | watchdog_enabled = 0; |
| 889 | } |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 890 | |
| 891 | mutex_unlock(&watchdog_proc_mutex); |
| 892 | |
| 893 | return ret; |
| 894 | } |
| 895 | |
| 896 | /* |
| 897 | * Resume the hard and soft lockup detector by unparking the watchdog threads. |
| 898 | */ |
Ulrich Obergfell | ec6a906 | 2015-09-04 15:45:28 -0700 | [diff] [blame] | 899 | void lockup_detector_resume(void) |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 900 | { |
| 901 | mutex_lock(&watchdog_proc_mutex); |
| 902 | |
| 903 | watchdog_suspended--; |
| 904 | /* |
| 905 | * The watchdog threads are unparked if they were previously running |
| 906 | * and if there is no more active suspend request. |
| 907 | */ |
| 908 | if (watchdog_running && !watchdog_suspended) |
| 909 | watchdog_unpark_threads(); |
| 910 | |
| 911 | mutex_unlock(&watchdog_proc_mutex); |
Ulrich Obergfell | ee89e71 | 2015-11-05 18:44:47 -0800 | [diff] [blame] | 912 | put_online_cpus(); |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 913 | } |
| 914 | |
Ulrich Obergfell | b43cb43 | 2015-11-05 18:44:33 -0800 | [diff] [blame] | 915 | static int update_watchdog_all_cpus(void) |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 916 | { |
Ulrich Obergfell | b43cb43 | 2015-11-05 18:44:33 -0800 | [diff] [blame] | 917 | int ret; |
| 918 | |
| 919 | ret = watchdog_park_threads(); |
| 920 | if (ret) |
| 921 | return ret; |
| 922 | |
Ulrich Obergfell | d4bdd0b | 2015-09-04 15:45:21 -0700 | [diff] [blame] | 923 | watchdog_unpark_threads(); |
Ulrich Obergfell | b43cb43 | 2015-11-05 18:44:33 -0800 | [diff] [blame] | 924 | |
| 925 | return 0; |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 926 | } |
| 927 | |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame] | 928 | static int watchdog_enable_all_cpus(void) |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 929 | { |
| 930 | int err = 0; |
| 931 | |
Frederic Weisbecker | 3c00ea8 | 2013-05-19 20:45:15 +0200 | [diff] [blame] | 932 | if (!watchdog_running) { |
Frederic Weisbecker | 230ec93 | 2015-09-04 15:45:06 -0700 | [diff] [blame] | 933 | err = smpboot_register_percpu_thread_cpumask(&watchdog_threads, |
| 934 | &watchdog_cpumask); |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 935 | if (err) |
| 936 | pr_err("Failed to create watchdog threads, disabled\n"); |
Frederic Weisbecker | 230ec93 | 2015-09-04 15:45:06 -0700 | [diff] [blame] | 937 | else |
Frederic Weisbecker | 3c00ea8 | 2013-05-19 20:45:15 +0200 | [diff] [blame] | 938 | watchdog_running = 1; |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame] | 939 | } else { |
| 940 | /* |
| 941 | * Enable/disable the lockup detectors or |
| 942 | * change the sample period 'on the fly'. |
| 943 | */ |
Ulrich Obergfell | b43cb43 | 2015-11-05 18:44:33 -0800 | [diff] [blame] | 944 | err = update_watchdog_all_cpus(); |
| 945 | |
| 946 | if (err) { |
| 947 | watchdog_disable_all_cpus(); |
| 948 | pr_err("Failed to update lockup detectors, disabled\n"); |
| 949 | } |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 950 | } |
| 951 | |
Ulrich Obergfell | b43cb43 | 2015-11-05 18:44:33 -0800 | [diff] [blame] | 952 | if (err) |
| 953 | watchdog_enabled = 0; |
| 954 | |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 955 | return err; |
| 956 | } |
| 957 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 958 | static void watchdog_disable_all_cpus(void) |
| 959 | { |
Frederic Weisbecker | 3c00ea8 | 2013-05-19 20:45:15 +0200 | [diff] [blame] | 960 | if (watchdog_running) { |
| 961 | watchdog_running = 0; |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 962 | smpboot_unregister_percpu_thread(&watchdog_threads); |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 963 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 964 | } |
| 965 | |
Ulrich Obergfell | 58cf690 | 2015-11-05 18:44:30 -0800 | [diff] [blame] | 966 | #ifdef CONFIG_SYSCTL |
| 967 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 968 | /* |
Ulrich Obergfell | a0c9cbb | 2015-04-14 15:43:58 -0700 | [diff] [blame] | 969 | * Update the run state of the lockup detectors. |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 970 | */ |
Ulrich Obergfell | a0c9cbb | 2015-04-14 15:43:58 -0700 | [diff] [blame] | 971 | static int proc_watchdog_update(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 972 | { |
Ulrich Obergfell | a0c9cbb | 2015-04-14 15:43:58 -0700 | [diff] [blame] | 973 | int err = 0; |
| 974 | |
| 975 | /* |
| 976 | * Watchdog threads won't be started if they are already active. |
| 977 | * The 'watchdog_running' variable in watchdog_*_all_cpus() takes |
| 978 | * care of this. If those threads are already active, the sample |
| 979 | * period will be updated and the lockup detectors will be enabled |
| 980 | * or disabled 'on the fly'. |
| 981 | */ |
| 982 | if (watchdog_enabled && watchdog_thresh) |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame] | 983 | err = watchdog_enable_all_cpus(); |
Ulrich Obergfell | a0c9cbb | 2015-04-14 15:43:58 -0700 | [diff] [blame] | 984 | else |
| 985 | watchdog_disable_all_cpus(); |
| 986 | |
| 987 | return err; |
| 988 | |
| 989 | } |
| 990 | |
| 991 | /* |
Ulrich Obergfell | ef246a2 | 2015-04-14 15:44:05 -0700 | [diff] [blame] | 992 | * common function for watchdog, nmi_watchdog and soft_watchdog parameter |
| 993 | * |
| 994 | * caller | table->data points to | 'which' contains the flag(s) |
| 995 | * -------------------|-----------------------|----------------------------- |
| 996 | * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED or'ed |
| 997 | * | | with SOFT_WATCHDOG_ENABLED |
| 998 | * -------------------|-----------------------|----------------------------- |
| 999 | * proc_nmi_watchdog | nmi_watchdog_enabled | NMI_WATCHDOG_ENABLED |
| 1000 | * -------------------|-----------------------|----------------------------- |
| 1001 | * proc_soft_watchdog | soft_watchdog_enabled | SOFT_WATCHDOG_ENABLED |
| 1002 | */ |
| 1003 | static int proc_watchdog_common(int which, struct ctl_table *table, int write, |
| 1004 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1005 | { |
| 1006 | int err, old, new; |
| 1007 | int *watchdog_param = (int *)table->data; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 1008 | |
Ulrich Obergfell | 8614dde | 2015-11-05 18:44:50 -0800 | [diff] [blame] | 1009 | get_online_cpus(); |
Michal Hocko | 359e6fa | 2013-09-24 15:27:29 -0700 | [diff] [blame] | 1010 | mutex_lock(&watchdog_proc_mutex); |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 1011 | |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 1012 | if (watchdog_suspended) { |
| 1013 | /* no parameter changes allowed while watchdog is suspended */ |
| 1014 | err = -EAGAIN; |
| 1015 | goto out; |
| 1016 | } |
| 1017 | |
Ulrich Obergfell | ef246a2 | 2015-04-14 15:44:05 -0700 | [diff] [blame] | 1018 | /* |
| 1019 | * If the parameter is being read return the state of the corresponding |
| 1020 | * bit(s) in 'watchdog_enabled', else update 'watchdog_enabled' and the |
| 1021 | * run state of the lockup detectors. |
| 1022 | */ |
| 1023 | if (!write) { |
| 1024 | *watchdog_param = (watchdog_enabled & which) != 0; |
| 1025 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| 1026 | } else { |
| 1027 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| 1028 | if (err) |
| 1029 | goto out; |
| 1030 | |
| 1031 | /* |
| 1032 | * There is a race window between fetching the current value |
| 1033 | * from 'watchdog_enabled' and storing the new value. During |
| 1034 | * this race window, watchdog_nmi_enable() can sneak in and |
| 1035 | * clear the NMI_WATCHDOG_ENABLED bit in 'watchdog_enabled'. |
| 1036 | * The 'cmpxchg' detects this race and the loop retries. |
| 1037 | */ |
| 1038 | do { |
| 1039 | old = watchdog_enabled; |
| 1040 | /* |
| 1041 | * If the parameter value is not zero set the |
| 1042 | * corresponding bit(s), else clear it(them). |
| 1043 | */ |
| 1044 | if (*watchdog_param) |
| 1045 | new = old | which; |
| 1046 | else |
| 1047 | new = old & ~which; |
| 1048 | } while (cmpxchg(&watchdog_enabled, old, new) != old); |
| 1049 | |
| 1050 | /* |
Ulrich Obergfell | b43cb43 | 2015-11-05 18:44:33 -0800 | [diff] [blame] | 1051 | * Update the run state of the lockup detectors. There is _no_ |
| 1052 | * need to check the value returned by proc_watchdog_update() |
| 1053 | * and to restore the previous value of 'watchdog_enabled' as |
| 1054 | * both lockup detectors are disabled if proc_watchdog_update() |
| 1055 | * returns an error. |
Ulrich Obergfell | ef246a2 | 2015-04-14 15:44:05 -0700 | [diff] [blame] | 1056 | */ |
Joshua Hunt | a1ee193 | 2016-03-17 14:17:23 -0700 | [diff] [blame] | 1057 | if (old == new) |
| 1058 | goto out; |
| 1059 | |
Ulrich Obergfell | ef246a2 | 2015-04-14 15:44:05 -0700 | [diff] [blame] | 1060 | err = proc_watchdog_update(); |
Ulrich Obergfell | ef246a2 | 2015-04-14 15:44:05 -0700 | [diff] [blame] | 1061 | } |
| 1062 | out: |
| 1063 | mutex_unlock(&watchdog_proc_mutex); |
Ulrich Obergfell | 8614dde | 2015-11-05 18:44:50 -0800 | [diff] [blame] | 1064 | put_online_cpus(); |
Ulrich Obergfell | ef246a2 | 2015-04-14 15:44:05 -0700 | [diff] [blame] | 1065 | return err; |
| 1066 | } |
| 1067 | |
| 1068 | /* |
Ulrich Obergfell | 83a80a3 | 2015-04-14 15:44:08 -0700 | [diff] [blame] | 1069 | * /proc/sys/kernel/watchdog |
| 1070 | */ |
| 1071 | int proc_watchdog(struct ctl_table *table, int write, |
| 1072 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1073 | { |
| 1074 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, |
| 1075 | table, write, buffer, lenp, ppos); |
| 1076 | } |
| 1077 | |
| 1078 | /* |
| 1079 | * /proc/sys/kernel/nmi_watchdog |
| 1080 | */ |
| 1081 | int proc_nmi_watchdog(struct ctl_table *table, int write, |
| 1082 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1083 | { |
| 1084 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED, |
| 1085 | table, write, buffer, lenp, ppos); |
| 1086 | } |
| 1087 | |
| 1088 | /* |
| 1089 | * /proc/sys/kernel/soft_watchdog |
| 1090 | */ |
| 1091 | int proc_soft_watchdog(struct ctl_table *table, int write, |
| 1092 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1093 | { |
| 1094 | return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, |
| 1095 | table, write, buffer, lenp, ppos); |
| 1096 | } |
| 1097 | |
| 1098 | /* |
| 1099 | * /proc/sys/kernel/watchdog_thresh |
| 1100 | */ |
| 1101 | int proc_watchdog_thresh(struct ctl_table *table, int write, |
| 1102 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1103 | { |
Joshua Hunt | a1ee193 | 2016-03-17 14:17:23 -0700 | [diff] [blame] | 1104 | int err, old, new; |
Ulrich Obergfell | 83a80a3 | 2015-04-14 15:44:08 -0700 | [diff] [blame] | 1105 | |
Ulrich Obergfell | 8614dde | 2015-11-05 18:44:50 -0800 | [diff] [blame] | 1106 | get_online_cpus(); |
Ulrich Obergfell | 83a80a3 | 2015-04-14 15:44:08 -0700 | [diff] [blame] | 1107 | mutex_lock(&watchdog_proc_mutex); |
| 1108 | |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 1109 | if (watchdog_suspended) { |
| 1110 | /* no parameter changes allowed while watchdog is suspended */ |
| 1111 | err = -EAGAIN; |
| 1112 | goto out; |
| 1113 | } |
| 1114 | |
Ulrich Obergfell | 83a80a3 | 2015-04-14 15:44:08 -0700 | [diff] [blame] | 1115 | old = ACCESS_ONCE(watchdog_thresh); |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 1116 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
Ulrich Obergfell | 83a80a3 | 2015-04-14 15:44:08 -0700 | [diff] [blame] | 1117 | |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 1118 | if (err || !write) |
Michal Hocko | 359e6fa | 2013-09-24 15:27:29 -0700 | [diff] [blame] | 1119 | goto out; |
Mandeep Singh Baines | e04ab2b | 2011-05-22 22:10:21 -0700 | [diff] [blame] | 1120 | |
anish kumar | b66a235 | 2013-03-12 14:44:08 -0400 | [diff] [blame] | 1121 | /* |
Ulrich Obergfell | d283c64 | 2015-11-05 18:44:27 -0800 | [diff] [blame] | 1122 | * Update the sample period. Restore on failure. |
anish kumar | b66a235 | 2013-03-12 14:44:08 -0400 | [diff] [blame] | 1123 | */ |
Joshua Hunt | a1ee193 | 2016-03-17 14:17:23 -0700 | [diff] [blame] | 1124 | new = ACCESS_ONCE(watchdog_thresh); |
| 1125 | if (old == new) |
| 1126 | goto out; |
| 1127 | |
Ulrich Obergfell | 83a80a3 | 2015-04-14 15:44:08 -0700 | [diff] [blame] | 1128 | set_sample_period(); |
| 1129 | err = proc_watchdog_update(); |
Ulrich Obergfell | d283c64 | 2015-11-05 18:44:27 -0800 | [diff] [blame] | 1130 | if (err) { |
Ulrich Obergfell | 83a80a3 | 2015-04-14 15:44:08 -0700 | [diff] [blame] | 1131 | watchdog_thresh = old; |
Ulrich Obergfell | d283c64 | 2015-11-05 18:44:27 -0800 | [diff] [blame] | 1132 | set_sample_period(); |
| 1133 | } |
Michal Hocko | 359e6fa | 2013-09-24 15:27:29 -0700 | [diff] [blame] | 1134 | out: |
| 1135 | mutex_unlock(&watchdog_proc_mutex); |
Ulrich Obergfell | 8614dde | 2015-11-05 18:44:50 -0800 | [diff] [blame] | 1136 | put_online_cpus(); |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 1137 | return err; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 1138 | } |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 1139 | |
| 1140 | /* |
| 1141 | * The cpumask is the mask of possible cpus that the watchdog can run |
| 1142 | * on, not the mask of cpus it is actually running on. This allows the |
| 1143 | * user to specify a mask that will include cpus that have not yet |
| 1144 | * been brought online, if desired. |
| 1145 | */ |
| 1146 | int proc_watchdog_cpumask(struct ctl_table *table, int write, |
| 1147 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1148 | { |
| 1149 | int err; |
| 1150 | |
Ulrich Obergfell | 8614dde | 2015-11-05 18:44:50 -0800 | [diff] [blame] | 1151 | get_online_cpus(); |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 1152 | mutex_lock(&watchdog_proc_mutex); |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 1153 | |
| 1154 | if (watchdog_suspended) { |
| 1155 | /* no parameter changes allowed while watchdog is suspended */ |
| 1156 | err = -EAGAIN; |
| 1157 | goto out; |
| 1158 | } |
| 1159 | |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 1160 | err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); |
| 1161 | if (!err && write) { |
| 1162 | /* Remove impossible cpus to keep sysctl output cleaner. */ |
| 1163 | cpumask_and(&watchdog_cpumask, &watchdog_cpumask, |
| 1164 | cpu_possible_mask); |
| 1165 | |
| 1166 | if (watchdog_running) { |
| 1167 | /* |
| 1168 | * Failure would be due to being unable to allocate |
| 1169 | * a temporary cpumask, so we are likely not in a |
| 1170 | * position to do much else to make things better. |
| 1171 | */ |
| 1172 | if (smpboot_update_cpumask_percpu_thread( |
| 1173 | &watchdog_threads, &watchdog_cpumask) != 0) |
| 1174 | pr_err("cpumask update failed\n"); |
| 1175 | } |
| 1176 | } |
Ulrich Obergfell | 8c073d2 | 2015-09-04 15:45:18 -0700 | [diff] [blame] | 1177 | out: |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 1178 | mutex_unlock(&watchdog_proc_mutex); |
Ulrich Obergfell | 8614dde | 2015-11-05 18:44:50 -0800 | [diff] [blame] | 1179 | put_online_cpus(); |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 1180 | return err; |
| 1181 | } |
| 1182 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 1183 | #endif /* CONFIG_SYSCTL */ |
| 1184 | |
Peter Zijlstra | 004417a | 2010-11-25 18:38:29 +0100 | [diff] [blame] | 1185 | void __init lockup_detector_init(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 1186 | { |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 1187 | set_sample_period(); |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 1188 | |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 1189 | #ifdef CONFIG_NO_HZ_FULL |
| 1190 | if (tick_nohz_full_enabled()) { |
Frederic Weisbecker | 314b08ff | 2015-09-04 15:45:09 -0700 | [diff] [blame] | 1191 | pr_info("Disabling watchdog on nohz_full cores by default\n"); |
| 1192 | cpumask_copy(&watchdog_cpumask, housekeeping_mask); |
Chris Metcalf | fe4ba3c | 2015-06-24 16:55:45 -0700 | [diff] [blame] | 1193 | } else |
| 1194 | cpumask_copy(&watchdog_cpumask, cpu_possible_mask); |
| 1195 | #else |
| 1196 | cpumask_copy(&watchdog_cpumask, cpu_possible_mask); |
| 1197 | #endif |
| 1198 | |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 1199 | if (watchdog_enabled) |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame] | 1200 | watchdog_enable_all_cpus(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 1201 | } |