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> |
| 16 | #include <linux/nmi.h> |
| 17 | #include <linux/init.h> |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 18 | #include <linux/module.h> |
| 19 | #include <linux/sysctl.h> |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 20 | #include <linux/smpboot.h> |
Clark Williams | 8bd75c7 | 2013-02-07 09:47:07 -0600 | [diff] [blame] | 21 | #include <linux/sched/rt.h> |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 22 | |
| 23 | #include <asm/irq_regs.h> |
Eric B Munson | 5d1c0f4 | 2012-03-10 14:37:28 -0500 | [diff] [blame] | 24 | #include <linux/kvm_para.h> |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 25 | #include <linux/perf_event.h> |
| 26 | |
Ulrich Obergfell | 84d56e6 | 2015-04-14 15:43:55 -0700 | [diff] [blame] | 27 | /* |
| 28 | * The run state of the lockup detectors is controlled by the content of the |
| 29 | * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit - |
| 30 | * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector. |
| 31 | * |
| 32 | * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled' |
| 33 | * are variables that are only used as an 'interface' between the parameters |
| 34 | * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The |
| 35 | * 'watchdog_thresh' variable is handled differently because its value is not |
| 36 | * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh' |
| 37 | * is equal zero. |
| 38 | */ |
| 39 | #define NMI_WATCHDOG_ENABLED_BIT 0 |
| 40 | #define SOFT_WATCHDOG_ENABLED_BIT 1 |
| 41 | #define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT) |
| 42 | #define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT) |
| 43 | |
| 44 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
| 45 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED; |
| 46 | #else |
| 47 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED; |
| 48 | #endif |
| 49 | int __read_mostly nmi_watchdog_enabled; |
| 50 | int __read_mostly soft_watchdog_enabled; |
| 51 | int __read_mostly watchdog_user_enabled; |
Mandeep Singh Baines | 4eec42f | 2011-05-22 22:10:23 -0700 | [diff] [blame] | 52 | int __read_mostly watchdog_thresh = 10; |
Ulrich Obergfell | 84d56e6 | 2015-04-14 15:43:55 -0700 | [diff] [blame] | 53 | |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 54 | #ifdef CONFIG_SMP |
| 55 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; |
| 56 | #else |
| 57 | #define sysctl_softlockup_all_cpu_backtrace 0 |
| 58 | #endif |
| 59 | |
Frederic Weisbecker | 3c00ea8 | 2013-05-19 20:45:15 +0200 | [diff] [blame] | 60 | static int __read_mostly watchdog_running; |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 61 | static u64 __read_mostly sample_period; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 62 | |
| 63 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); |
| 64 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); |
| 65 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); |
| 66 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 67 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 68 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
| 69 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); |
chai wen | b1a8de1 | 2014-10-09 15:25:17 -0700 | [diff] [blame] | 70 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
Frederic Weisbecker | 23637d4 | 2010-05-15 23:15:20 +0200 | [diff] [blame] | 71 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Don Zickus | cafcd80 | 2010-05-14 11:11:21 -0400 | [diff] [blame] | 72 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
| 73 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 74 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
| 75 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); |
| 76 | #endif |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 77 | static unsigned long soft_lockup_nmi_warn; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 78 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 79 | /* boot commands */ |
| 80 | /* |
| 81 | * Should we panic when a soft-lockup or hard-lockup occurs: |
| 82 | */ |
Frederic Weisbecker | 23637d4 | 2010-05-15 23:15:20 +0200 | [diff] [blame] | 83 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Don Zickus | fef2c9b | 2011-03-22 16:34:16 -0700 | [diff] [blame] | 84 | static int hardlockup_panic = |
| 85 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 86 | |
Ulrich Obergfell | 6e7458a | 2014-10-13 15:55:35 -0700 | [diff] [blame] | 87 | static bool hardlockup_detector_enabled = true; |
| 88 | /* |
| 89 | * We may not want to enable hard lockup detection by default in all cases, |
| 90 | * for example when running the kernel as a guest on a hypervisor. In these |
| 91 | * cases this function can be called to disable hard lockup detection. This |
| 92 | * function should only be executed once by the boot processor before the |
| 93 | * kernel command line parameters are parsed, because otherwise it is not |
| 94 | * possible to override this in hardlockup_panic_setup(). |
| 95 | */ |
| 96 | void watchdog_enable_hardlockup_detector(bool val) |
| 97 | { |
| 98 | hardlockup_detector_enabled = val; |
| 99 | } |
| 100 | |
| 101 | bool watchdog_hardlockup_detector_is_enabled(void) |
| 102 | { |
| 103 | return hardlockup_detector_enabled; |
| 104 | } |
| 105 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 106 | static int __init hardlockup_panic_setup(char *str) |
| 107 | { |
| 108 | if (!strncmp(str, "panic", 5)) |
| 109 | hardlockup_panic = 1; |
Don Zickus | fef2c9b | 2011-03-22 16:34:16 -0700 | [diff] [blame] | 110 | else if (!strncmp(str, "nopanic", 7)) |
| 111 | hardlockup_panic = 0; |
Don Zickus | 5dc3055 | 2010-11-29 17:07:17 -0500 | [diff] [blame] | 112 | else if (!strncmp(str, "0", 1)) |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 113 | watchdog_enabled &= ~NMI_WATCHDOG_ENABLED; |
| 114 | else if (!strncmp(str, "1", 1)) |
| 115 | watchdog_enabled |= NMI_WATCHDOG_ENABLED; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 116 | return 1; |
| 117 | } |
| 118 | __setup("nmi_watchdog=", hardlockup_panic_setup); |
| 119 | #endif |
| 120 | |
| 121 | unsigned int __read_mostly softlockup_panic = |
| 122 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; |
| 123 | |
| 124 | static int __init softlockup_panic_setup(char *str) |
| 125 | { |
| 126 | softlockup_panic = simple_strtoul(str, NULL, 0); |
| 127 | |
| 128 | return 1; |
| 129 | } |
| 130 | __setup("softlockup_panic=", softlockup_panic_setup); |
| 131 | |
| 132 | static int __init nowatchdog_setup(char *str) |
| 133 | { |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 134 | watchdog_enabled = 0; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 135 | return 1; |
| 136 | } |
| 137 | __setup("nowatchdog", nowatchdog_setup); |
| 138 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 139 | static int __init nosoftlockup_setup(char *str) |
| 140 | { |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 141 | watchdog_enabled &= ~SOFT_WATCHDOG_ENABLED; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 142 | return 1; |
| 143 | } |
| 144 | __setup("nosoftlockup", nosoftlockup_setup); |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 145 | |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 146 | #ifdef CONFIG_SMP |
| 147 | static int __init softlockup_all_cpu_backtrace_setup(char *str) |
| 148 | { |
| 149 | sysctl_softlockup_all_cpu_backtrace = |
| 150 | !!simple_strtol(str, NULL, 0); |
| 151 | return 1; |
| 152 | } |
| 153 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); |
| 154 | #endif |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 155 | |
Mandeep Singh Baines | 4eec42f | 2011-05-22 22:10:23 -0700 | [diff] [blame] | 156 | /* |
| 157 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- |
| 158 | * lockups can have false positives under extreme conditions. So we generally |
| 159 | * want a higher threshold for soft lockups than for hard lockups. So we couple |
| 160 | * the thresholds with a factor: we make the soft threshold twice the amount of |
| 161 | * time the hard threshold is. |
| 162 | */ |
Ingo Molnar | 6e9101a | 2011-05-24 05:43:18 +0200 | [diff] [blame] | 163 | static int get_softlockup_thresh(void) |
Mandeep Singh Baines | 4eec42f | 2011-05-22 22:10:23 -0700 | [diff] [blame] | 164 | { |
| 165 | return watchdog_thresh * 2; |
| 166 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 167 | |
| 168 | /* |
| 169 | * Returns seconds, approximately. We don't need nanosecond |
| 170 | * resolution, and we don't need to waste time with a big divide when |
| 171 | * 2^30ns == 1.074s. |
| 172 | */ |
Namhyung Kim | c06b4f1 | 2012-12-27 11:49:44 +0900 | [diff] [blame] | 173 | static unsigned long get_timestamp(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 174 | { |
Cyril Bur | 545a2bf | 2015-02-12 15:01:24 -0800 | [diff] [blame] | 175 | return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 176 | } |
| 177 | |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 178 | static void set_sample_period(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 179 | { |
| 180 | /* |
Mandeep Singh Baines | 586692a | 2011-05-22 22:10:22 -0700 | [diff] [blame] | 181 | * convert watchdog_thresh from seconds to ns |
Fernando Luis Vázquez Cao | 86f5e6a | 2012-02-09 17:42:22 -0500 | [diff] [blame] | 182 | * the divide by 5 is to give hrtimer several chances (two |
| 183 | * or three with the current relation between the soft |
| 184 | * and hard thresholds) to increment before the |
| 185 | * hardlockup detector generates a warning |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 186 | */ |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 187 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 188 | } |
| 189 | |
| 190 | /* Commands for resetting the watchdog */ |
| 191 | static void __touch_watchdog(void) |
| 192 | { |
Namhyung Kim | c06b4f1 | 2012-12-27 11:49:44 +0900 | [diff] [blame] | 193 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 194 | } |
| 195 | |
Don Zickus | 332fbdb | 2010-05-07 17:11:45 -0400 | [diff] [blame] | 196 | void touch_softlockup_watchdog(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 197 | { |
Andrew Morton | 7861144 | 2014-04-18 15:07:12 -0700 | [diff] [blame] | 198 | /* |
| 199 | * Preemption can be enabled. It doesn't matter which CPU's timestamp |
| 200 | * gets zeroed here, so use the raw_ operation. |
| 201 | */ |
| 202 | raw_cpu_write(watchdog_touch_ts, 0); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 203 | } |
Ingo Molnar | 0167c78 | 2010-05-13 08:53:33 +0200 | [diff] [blame] | 204 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 205 | |
Don Zickus | 332fbdb | 2010-05-07 17:11:45 -0400 | [diff] [blame] | 206 | void touch_all_softlockup_watchdogs(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 207 | { |
| 208 | int cpu; |
| 209 | |
| 210 | /* |
| 211 | * this is done lockless |
| 212 | * do we care if a 0 races with a timestamp? |
| 213 | * all it means is the softlock check starts one cycle later |
| 214 | */ |
| 215 | for_each_online_cpu(cpu) |
| 216 | per_cpu(watchdog_touch_ts, cpu) = 0; |
| 217 | } |
| 218 | |
Don Zickus | cafcd80 | 2010-05-14 11:11:21 -0400 | [diff] [blame] | 219 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 220 | void touch_nmi_watchdog(void) |
| 221 | { |
Ben Zhang | 62572e2 | 2014-04-03 14:47:18 -0700 | [diff] [blame] | 222 | /* |
| 223 | * Using __raw here because some code paths have |
| 224 | * preemption enabled. If preemption is enabled |
| 225 | * then interrupts should be enabled too, in which |
| 226 | * case we shouldn't have to worry about the watchdog |
| 227 | * going off. |
| 228 | */ |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 229 | raw_cpu_write(watchdog_nmi_touch, true); |
Don Zickus | 332fbdb | 2010-05-07 17:11:45 -0400 | [diff] [blame] | 230 | touch_softlockup_watchdog(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 231 | } |
| 232 | EXPORT_SYMBOL(touch_nmi_watchdog); |
| 233 | |
Don Zickus | cafcd80 | 2010-05-14 11:11:21 -0400 | [diff] [blame] | 234 | #endif |
| 235 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 236 | void touch_softlockup_watchdog_sync(void) |
| 237 | { |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 238 | __this_cpu_write(softlockup_touch_sync, true); |
| 239 | __this_cpu_write(watchdog_touch_ts, 0); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 240 | } |
| 241 | |
Frederic Weisbecker | 23637d4 | 2010-05-15 23:15:20 +0200 | [diff] [blame] | 242 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 243 | /* watchdog detector functions */ |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 244 | static int is_hardlockup(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 245 | { |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 246 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 247 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 248 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 249 | return 1; |
| 250 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 251 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 252 | return 0; |
| 253 | } |
| 254 | #endif |
| 255 | |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 256 | static int is_softlockup(unsigned long touch_ts) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 257 | { |
Namhyung Kim | c06b4f1 | 2012-12-27 11:49:44 +0900 | [diff] [blame] | 258 | unsigned long now = get_timestamp(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 259 | |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 260 | if (watchdog_enabled & SOFT_WATCHDOG_ENABLED) { |
| 261 | /* Warn about unreasonable delays. */ |
| 262 | if (time_after(now, touch_ts + get_softlockup_thresh())) |
| 263 | return now - touch_ts; |
| 264 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 265 | return 0; |
| 266 | } |
| 267 | |
Frederic Weisbecker | 23637d4 | 2010-05-15 23:15:20 +0200 | [diff] [blame] | 268 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Cyrill Gorcunov | 1880c4a | 2011-06-23 16:49:18 +0400 | [diff] [blame] | 269 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 270 | static struct perf_event_attr wd_hw_attr = { |
| 271 | .type = PERF_TYPE_HARDWARE, |
| 272 | .config = PERF_COUNT_HW_CPU_CYCLES, |
| 273 | .size = sizeof(struct perf_event_attr), |
| 274 | .pinned = 1, |
| 275 | .disabled = 1, |
| 276 | }; |
| 277 | |
| 278 | /* Callback function for perf event subsystem */ |
Peter Zijlstra | a8b0ca1 | 2011-06-27 14:41:57 +0200 | [diff] [blame] | 279 | static void watchdog_overflow_callback(struct perf_event *event, |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 280 | struct perf_sample_data *data, |
| 281 | struct pt_regs *regs) |
| 282 | { |
Peter Zijlstra | c6db67c | 2010-08-20 11:49:15 +0200 | [diff] [blame] | 283 | /* Ensure the watchdog never gets throttled */ |
| 284 | event->hw.interrupts = 0; |
| 285 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 286 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
| 287 | __this_cpu_write(watchdog_nmi_touch, false); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 288 | return; |
| 289 | } |
| 290 | |
| 291 | /* check for a hardlockup |
| 292 | * This is done by making sure our timer interrupt |
| 293 | * is incrementing. The timer interrupt should have |
| 294 | * fired multiple times before we overflow'd. If it hasn't |
| 295 | * then this is a good indication the cpu is stuck |
| 296 | */ |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 297 | if (is_hardlockup()) { |
| 298 | int this_cpu = smp_processor_id(); |
| 299 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 300 | /* only print hardlockups once */ |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 301 | if (__this_cpu_read(hard_watchdog_warn) == true) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 302 | return; |
| 303 | |
| 304 | if (hardlockup_panic) |
Fabian Frederick | 656c3b7 | 2014-08-06 16:04:03 -0700 | [diff] [blame] | 305 | panic("Watchdog detected hard LOCKUP on cpu %d", |
| 306 | this_cpu); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 307 | else |
Fabian Frederick | 656c3b7 | 2014-08-06 16:04:03 -0700 | [diff] [blame] | 308 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", |
| 309 | this_cpu); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 310 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 311 | __this_cpu_write(hard_watchdog_warn, true); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 312 | return; |
| 313 | } |
| 314 | |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 315 | __this_cpu_write(hard_watchdog_warn, false); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 316 | return; |
| 317 | } |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 318 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
| 319 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 320 | static void watchdog_interrupt_count(void) |
| 321 | { |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 322 | __this_cpu_inc(hrtimer_interrupts); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 323 | } |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 324 | |
| 325 | static int watchdog_nmi_enable(unsigned int cpu); |
| 326 | static void watchdog_nmi_disable(unsigned int cpu); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 327 | |
| 328 | /* watchdog kicker functions */ |
| 329 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) |
| 330 | { |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 331 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 332 | struct pt_regs *regs = get_irq_regs(); |
| 333 | int duration; |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 334 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 335 | |
| 336 | /* kick the hardlockup detector */ |
| 337 | watchdog_interrupt_count(); |
| 338 | |
| 339 | /* kick the softlockup detector */ |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 340 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 341 | |
| 342 | /* .. and repeat */ |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 343 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 344 | |
| 345 | if (touch_ts == 0) { |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 346 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 347 | /* |
| 348 | * If the time stamp was touched atomically |
| 349 | * make sure the scheduler tick is up to date. |
| 350 | */ |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 351 | __this_cpu_write(softlockup_touch_sync, false); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 352 | sched_clock_tick(); |
| 353 | } |
Eric B Munson | 5d1c0f4 | 2012-03-10 14:37:28 -0500 | [diff] [blame] | 354 | |
| 355 | /* Clear the guest paused flag on watchdog reset */ |
| 356 | kvm_check_and_clear_guest_paused(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 357 | __touch_watchdog(); |
| 358 | return HRTIMER_RESTART; |
| 359 | } |
| 360 | |
| 361 | /* check for a softlockup |
| 362 | * This is done by making sure a high priority task is |
| 363 | * being scheduled. The task touches the watchdog to |
| 364 | * indicate it is getting cpu time. If it hasn't then |
| 365 | * this is a good indication some task is hogging the cpu |
| 366 | */ |
Don Zickus | 26e09c6 | 2010-05-17 18:06:04 -0400 | [diff] [blame] | 367 | duration = is_softlockup(touch_ts); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 368 | if (unlikely(duration)) { |
Eric B Munson | 5d1c0f4 | 2012-03-10 14:37:28 -0500 | [diff] [blame] | 369 | /* |
| 370 | * If a virtual machine is stopped by the host it can look to |
| 371 | * the watchdog like a soft lockup, check to see if the host |
| 372 | * stopped the vm before we issue the warning |
| 373 | */ |
| 374 | if (kvm_check_and_clear_guest_paused()) |
| 375 | return HRTIMER_RESTART; |
| 376 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 377 | /* only warn once */ |
chai wen | b1a8de1 | 2014-10-09 15:25:17 -0700 | [diff] [blame] | 378 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
| 379 | /* |
| 380 | * When multiple processes are causing softlockups the |
| 381 | * softlockup detector only warns on the first one |
| 382 | * because the code relies on a full quiet cycle to |
| 383 | * re-arm. The second process prevents the quiet cycle |
| 384 | * and never gets reported. Use task pointers to detect |
| 385 | * this. |
| 386 | */ |
| 387 | if (__this_cpu_read(softlockup_task_ptr_saved) != |
| 388 | current) { |
| 389 | __this_cpu_write(soft_watchdog_warn, false); |
| 390 | __touch_watchdog(); |
| 391 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 392 | return HRTIMER_RESTART; |
chai wen | b1a8de1 | 2014-10-09 15:25:17 -0700 | [diff] [blame] | 393 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 394 | |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 395 | if (softlockup_all_cpu_backtrace) { |
| 396 | /* Prevent multiple soft-lockup reports if one cpu is already |
| 397 | * engaged in dumping cpu back traces |
| 398 | */ |
| 399 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { |
| 400 | /* Someone else will report us. Let's give up */ |
| 401 | __this_cpu_write(soft_watchdog_warn, true); |
| 402 | return HRTIMER_RESTART; |
| 403 | } |
| 404 | } |
| 405 | |
Fabian Frederick | 656c3b7 | 2014-08-06 16:04:03 -0700 | [diff] [blame] | 406 | 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] | 407 | smp_processor_id(), duration, |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 408 | current->comm, task_pid_nr(current)); |
chai wen | b1a8de1 | 2014-10-09 15:25:17 -0700 | [diff] [blame] | 409 | __this_cpu_write(softlockup_task_ptr_saved, current); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 410 | print_modules(); |
| 411 | print_irqtrace_events(current); |
| 412 | if (regs) |
| 413 | show_regs(regs); |
| 414 | else |
| 415 | dump_stack(); |
| 416 | |
Aaron Tomlin | ed23587 | 2014-06-23 13:22:05 -0700 | [diff] [blame] | 417 | if (softlockup_all_cpu_backtrace) { |
| 418 | /* Avoid generating two back traces for current |
| 419 | * given that one is already made above |
| 420 | */ |
| 421 | trigger_allbutself_cpu_backtrace(); |
| 422 | |
| 423 | clear_bit(0, &soft_lockup_nmi_warn); |
| 424 | /* Barrier to sync with other cpus */ |
| 425 | smp_mb__after_atomic(); |
| 426 | } |
| 427 | |
Josh Hunt | 69361ee | 2014-08-08 14:22:31 -0700 | [diff] [blame] | 428 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 429 | if (softlockup_panic) |
| 430 | panic("softlockup: hung tasks"); |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 431 | __this_cpu_write(soft_watchdog_warn, true); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 432 | } else |
Christoph Lameter | 909ea96 | 2010-12-08 16:22:55 +0100 | [diff] [blame] | 433 | __this_cpu_write(soft_watchdog_warn, false); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 434 | |
| 435 | return HRTIMER_RESTART; |
| 436 | } |
| 437 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 438 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 439 | { |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 440 | struct sched_param param = { .sched_priority = prio }; |
| 441 | |
| 442 | sched_setscheduler(current, policy, ¶m); |
| 443 | } |
| 444 | |
| 445 | static void watchdog_enable(unsigned int cpu) |
| 446 | { |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 447 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 448 | |
Bjørn Mork | 3935e895 | 2012-12-19 20:51:31 +0100 | [diff] [blame] | 449 | /* kick off the timer for the hardlockup detector */ |
| 450 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| 451 | hrtimer->function = watchdog_timer_fn; |
| 452 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 453 | /* Enable the perf event */ |
| 454 | watchdog_nmi_enable(cpu); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 455 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 456 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 457 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 458 | HRTIMER_MODE_REL_PINNED); |
| 459 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 460 | /* initialize timestamp */ |
| 461 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); |
| 462 | __touch_watchdog(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 463 | } |
| 464 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 465 | static void watchdog_disable(unsigned int cpu) |
| 466 | { |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 467 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 468 | |
| 469 | watchdog_set_prio(SCHED_NORMAL, 0); |
| 470 | hrtimer_cancel(hrtimer); |
| 471 | /* disable the perf event */ |
| 472 | watchdog_nmi_disable(cpu); |
| 473 | } |
| 474 | |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 475 | static void watchdog_cleanup(unsigned int cpu, bool online) |
| 476 | { |
| 477 | watchdog_disable(cpu); |
| 478 | } |
| 479 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 480 | static int watchdog_should_run(unsigned int cpu) |
| 481 | { |
| 482 | return __this_cpu_read(hrtimer_interrupts) != |
| 483 | __this_cpu_read(soft_lockup_hrtimer_cnt); |
| 484 | } |
| 485 | |
| 486 | /* |
| 487 | * The watchdog thread function - touches the timestamp. |
| 488 | * |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 489 | * It only runs once every sample_period seconds (4 seconds by |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 490 | * default) to reset the softlockup timestamp. If this gets delayed |
| 491 | * for more than 2*watchdog_thresh seconds then the debug-printout |
| 492 | * triggers in watchdog_timer_fn(). |
| 493 | */ |
| 494 | static void watchdog(unsigned int cpu) |
| 495 | { |
| 496 | __this_cpu_write(soft_lockup_hrtimer_cnt, |
| 497 | __this_cpu_read(hrtimer_interrupts)); |
| 498 | __touch_watchdog(); |
Ulrich Obergfell | bcfba4f | 2015-04-14 15:44:10 -0700 | [diff] [blame] | 499 | |
| 500 | /* |
| 501 | * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the |
| 502 | * failure path. Check for failures that can occur asynchronously - |
| 503 | * for example, when CPUs are on-lined - and shut down the hardware |
| 504 | * perf event on each CPU accordingly. |
| 505 | * |
| 506 | * The only non-obvious place this bit can be cleared is through |
| 507 | * watchdog_nmi_enable(), so a pr_info() is placed there. Placing a |
| 508 | * pr_info here would be too noisy as it would result in a message |
| 509 | * every few seconds if the hardlockup was disabled but the softlockup |
| 510 | * enabled. |
| 511 | */ |
| 512 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) |
| 513 | watchdog_nmi_disable(cpu); |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 514 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 515 | |
Frederic Weisbecker | 23637d4 | 2010-05-15 23:15:20 +0200 | [diff] [blame] | 516 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
Don Zickus | a702704 | 2012-06-13 09:35:48 -0400 | [diff] [blame] | 517 | /* |
| 518 | * People like the simple clean cpu node info on boot. |
| 519 | * Reduce the watchdog noise by only printing messages |
| 520 | * that are different from what cpu0 displayed. |
| 521 | */ |
| 522 | static unsigned long cpu0_err; |
| 523 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 524 | static int watchdog_nmi_enable(unsigned int cpu) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 525 | { |
| 526 | struct perf_event_attr *wd_attr; |
| 527 | struct perf_event *event = per_cpu(watchdog_ev, cpu); |
| 528 | |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 529 | /* nothing to do if the hard lockup detector is disabled */ |
| 530 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) |
| 531 | goto out; |
| 532 | |
Ulrich Obergfell | 6e7458a | 2014-10-13 15:55:35 -0700 | [diff] [blame] | 533 | /* |
| 534 | * Some kernels need to default hard lockup detection to |
| 535 | * 'disabled', for example a guest on a hypervisor. |
| 536 | */ |
| 537 | if (!watchdog_hardlockup_detector_is_enabled()) { |
| 538 | event = ERR_PTR(-ENOENT); |
| 539 | goto handle_err; |
| 540 | } |
| 541 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 542 | /* is it already setup and enabled? */ |
| 543 | if (event && event->state > PERF_EVENT_STATE_OFF) |
| 544 | goto out; |
| 545 | |
| 546 | /* it is setup but not enabled */ |
| 547 | if (event != NULL) |
| 548 | goto out_enable; |
| 549 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 550 | wd_attr = &wd_hw_attr; |
Mandeep Singh Baines | 4eec42f | 2011-05-22 22:10:23 -0700 | [diff] [blame] | 551 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
Cyrill Gorcunov | 1880c4a | 2011-06-23 16:49:18 +0400 | [diff] [blame] | 552 | |
| 553 | /* Try to register using hardware perf events */ |
Avi Kivity | 4dc0da8 | 2011-06-29 18:42:35 +0300 | [diff] [blame] | 554 | 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] | 555 | |
Ulrich Obergfell | 6e7458a | 2014-10-13 15:55:35 -0700 | [diff] [blame] | 556 | handle_err: |
Don Zickus | a702704 | 2012-06-13 09:35:48 -0400 | [diff] [blame] | 557 | /* save cpu0 error for future comparision */ |
| 558 | if (cpu == 0 && IS_ERR(event)) |
| 559 | cpu0_err = PTR_ERR(event); |
| 560 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 561 | if (!IS_ERR(event)) { |
Don Zickus | a702704 | 2012-06-13 09:35:48 -0400 | [diff] [blame] | 562 | /* only print for cpu0 or different than cpu0 */ |
| 563 | if (cpu == 0 || cpu0_err) |
| 564 | 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] | 565 | goto out_save; |
| 566 | } |
| 567 | |
Ulrich Obergfell | bcfba4f | 2015-04-14 15:44:10 -0700 | [diff] [blame] | 568 | /* |
| 569 | * Disable the hard lockup detector if _any_ CPU fails to set up |
| 570 | * set up the hardware perf event. The watchdog() function checks |
| 571 | * the NMI_WATCHDOG_ENABLED bit periodically. |
| 572 | * |
| 573 | * The barriers are for syncing up watchdog_enabled across all the |
| 574 | * cpus, as clear_bit() does not use barriers. |
| 575 | */ |
| 576 | smp_mb__before_atomic(); |
| 577 | clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled); |
| 578 | smp_mb__after_atomic(); |
| 579 | |
Don Zickus | a702704 | 2012-06-13 09:35:48 -0400 | [diff] [blame] | 580 | /* skip displaying the same error again */ |
| 581 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) |
| 582 | return PTR_ERR(event); |
Don Zickus | 5651f7f | 2011-02-09 14:02:33 -0500 | [diff] [blame] | 583 | |
| 584 | /* vary the KERN level based on the returned errno */ |
| 585 | if (PTR_ERR(event) == -EOPNOTSUPP) |
Andrew Morton | 4501980 | 2012-03-23 15:01:55 -0700 | [diff] [blame] | 586 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
Don Zickus | 5651f7f | 2011-02-09 14:02:33 -0500 | [diff] [blame] | 587 | else if (PTR_ERR(event) == -ENOENT) |
Fabian Frederick | 656c3b7 | 2014-08-06 16:04:03 -0700 | [diff] [blame] | 588 | pr_warn("disabled (cpu%i): hardware events not enabled\n", |
Andrew Morton | 4501980 | 2012-03-23 15:01:55 -0700 | [diff] [blame] | 589 | cpu); |
Don Zickus | 5651f7f | 2011-02-09 14:02:33 -0500 | [diff] [blame] | 590 | else |
Andrew Morton | 4501980 | 2012-03-23 15:01:55 -0700 | [diff] [blame] | 591 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
| 592 | cpu, PTR_ERR(event)); |
Ulrich Obergfell | bcfba4f | 2015-04-14 15:44:10 -0700 | [diff] [blame] | 593 | |
| 594 | pr_info("Shutting down hard lockup detector on all cpus\n"); |
| 595 | |
Akinobu Mita | eac2433 | 2010-08-31 23:00:08 -0400 | [diff] [blame] | 596 | return PTR_ERR(event); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 597 | |
| 598 | /* success path */ |
| 599 | out_save: |
| 600 | per_cpu(watchdog_ev, cpu) = event; |
| 601 | out_enable: |
| 602 | perf_event_enable(per_cpu(watchdog_ev, cpu)); |
| 603 | out: |
| 604 | return 0; |
| 605 | } |
| 606 | |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 607 | static void watchdog_nmi_disable(unsigned int cpu) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 608 | { |
| 609 | struct perf_event *event = per_cpu(watchdog_ev, cpu); |
| 610 | |
| 611 | if (event) { |
| 612 | perf_event_disable(event); |
| 613 | per_cpu(watchdog_ev, cpu) = NULL; |
| 614 | |
| 615 | /* should be in cleanup, but blocks oprofile */ |
| 616 | perf_event_release_kernel(event); |
| 617 | } |
Ulrich Obergfell | df57714 | 2014-08-11 10:49:25 -0400 | [diff] [blame] | 618 | if (cpu == 0) { |
| 619 | /* watchdog_nmi_enable() expects this to be zero initially. */ |
| 620 | cpu0_err = 0; |
| 621 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 622 | } |
| 623 | #else |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 624 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
| 625 | static void watchdog_nmi_disable(unsigned int cpu) { return; } |
Frederic Weisbecker | 23637d4 | 2010-05-15 23:15:20 +0200 | [diff] [blame] | 626 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 627 | |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 628 | static struct smp_hotplug_thread watchdog_threads = { |
| 629 | .store = &softlockup_watchdog, |
| 630 | .thread_should_run = watchdog_should_run, |
| 631 | .thread_fn = watchdog, |
| 632 | .thread_comm = "watchdog/%u", |
| 633 | .setup = watchdog_enable, |
| 634 | .cleanup = watchdog_cleanup, |
| 635 | .park = watchdog_disable, |
| 636 | .unpark = watchdog_enable, |
| 637 | }; |
| 638 | |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 639 | static void restart_watchdog_hrtimer(void *info) |
| 640 | { |
Christoph Lameter | f7f66b0 | 2014-08-17 12:30:34 -0500 | [diff] [blame] | 641 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 642 | int ret; |
| 643 | |
| 644 | /* |
| 645 | * No need to cancel and restart hrtimer if it is currently executing |
| 646 | * because it will reprogram itself with the new period now. |
| 647 | * We should never see it unqueued here because we are running per-cpu |
| 648 | * with interrupts disabled. |
| 649 | */ |
| 650 | ret = hrtimer_try_to_cancel(hrtimer); |
| 651 | if (ret == 1) |
| 652 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
| 653 | HRTIMER_MODE_REL_PINNED); |
| 654 | } |
| 655 | |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame^] | 656 | static void update_watchdog(int cpu) |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 657 | { |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 658 | /* |
| 659 | * Make sure that perf event counter will adopt to a new |
| 660 | * sampling period. Updating the sampling period directly would |
| 661 | * be much nicer but we do not have an API for that now so |
| 662 | * let's use a big hammer. |
| 663 | * Hrtimer will adopt the new period on the next tick but this |
| 664 | * might be late already so we have to restart the timer as well. |
| 665 | */ |
| 666 | watchdog_nmi_disable(cpu); |
Frederic Weisbecker | e0a23b06 | 2014-02-24 16:40:00 +0100 | [diff] [blame] | 667 | smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1); |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 668 | watchdog_nmi_enable(cpu); |
| 669 | } |
| 670 | |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame^] | 671 | static void update_watchdog_all_cpus(void) |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 672 | { |
| 673 | int cpu; |
| 674 | |
| 675 | get_online_cpus(); |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 676 | for_each_online_cpu(cpu) |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame^] | 677 | update_watchdog(cpu); |
Michal Hocko | 9809b18 | 2013-09-24 15:27:30 -0700 | [diff] [blame] | 678 | put_online_cpus(); |
| 679 | } |
| 680 | |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame^] | 681 | static int watchdog_enable_all_cpus(void) |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 682 | { |
| 683 | int err = 0; |
| 684 | |
Frederic Weisbecker | 3c00ea8 | 2013-05-19 20:45:15 +0200 | [diff] [blame] | 685 | if (!watchdog_running) { |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 686 | err = smpboot_register_percpu_thread(&watchdog_threads); |
| 687 | if (err) |
| 688 | pr_err("Failed to create watchdog threads, disabled\n"); |
| 689 | else |
Frederic Weisbecker | 3c00ea8 | 2013-05-19 20:45:15 +0200 | [diff] [blame] | 690 | watchdog_running = 1; |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame^] | 691 | } else { |
| 692 | /* |
| 693 | * Enable/disable the lockup detectors or |
| 694 | * change the sample period 'on the fly'. |
| 695 | */ |
| 696 | update_watchdog_all_cpus(); |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 697 | } |
| 698 | |
| 699 | return err; |
| 700 | } |
| 701 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 702 | /* prepare/enable/disable routines */ |
Vasily Averin | 4ff8195 | 2011-10-31 17:11:18 -0700 | [diff] [blame] | 703 | /* sysctl functions */ |
| 704 | #ifdef CONFIG_SYSCTL |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 705 | static void watchdog_disable_all_cpus(void) |
| 706 | { |
Frederic Weisbecker | 3c00ea8 | 2013-05-19 20:45:15 +0200 | [diff] [blame] | 707 | if (watchdog_running) { |
| 708 | watchdog_running = 0; |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 709 | smpboot_unregister_percpu_thread(&watchdog_threads); |
Thomas Gleixner | bcd951c | 2012-07-16 10:42:38 +0000 | [diff] [blame] | 710 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 711 | } |
| 712 | |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 713 | /* |
Ulrich Obergfell | a0c9cbb | 2015-04-14 15:43:58 -0700 | [diff] [blame] | 714 | * Update the run state of the lockup detectors. |
| 715 | */ |
| 716 | static int proc_watchdog_update(void) |
| 717 | { |
| 718 | int err = 0; |
| 719 | |
| 720 | /* |
| 721 | * Watchdog threads won't be started if they are already active. |
| 722 | * The 'watchdog_running' variable in watchdog_*_all_cpus() takes |
| 723 | * care of this. If those threads are already active, the sample |
| 724 | * period will be updated and the lockup detectors will be enabled |
| 725 | * or disabled 'on the fly'. |
| 726 | */ |
| 727 | if (watchdog_enabled && watchdog_thresh) |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame^] | 728 | err = watchdog_enable_all_cpus(); |
Ulrich Obergfell | a0c9cbb | 2015-04-14 15:43:58 -0700 | [diff] [blame] | 729 | else |
| 730 | watchdog_disable_all_cpus(); |
| 731 | |
| 732 | return err; |
| 733 | |
| 734 | } |
| 735 | |
Ulrich Obergfell | f54c227 | 2015-04-14 15:44:01 -0700 | [diff] [blame] | 736 | static DEFINE_MUTEX(watchdog_proc_mutex); |
| 737 | |
Ulrich Obergfell | a0c9cbb | 2015-04-14 15:43:58 -0700 | [diff] [blame] | 738 | /* |
Ulrich Obergfell | ef246a2 | 2015-04-14 15:44:05 -0700 | [diff] [blame] | 739 | * common function for watchdog, nmi_watchdog and soft_watchdog parameter |
| 740 | * |
| 741 | * caller | table->data points to | 'which' contains the flag(s) |
| 742 | * -------------------|-----------------------|----------------------------- |
| 743 | * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED or'ed |
| 744 | * | | with SOFT_WATCHDOG_ENABLED |
| 745 | * -------------------|-----------------------|----------------------------- |
| 746 | * proc_nmi_watchdog | nmi_watchdog_enabled | NMI_WATCHDOG_ENABLED |
| 747 | * -------------------|-----------------------|----------------------------- |
| 748 | * proc_soft_watchdog | soft_watchdog_enabled | SOFT_WATCHDOG_ENABLED |
| 749 | */ |
| 750 | static int proc_watchdog_common(int which, struct ctl_table *table, int write, |
| 751 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 752 | { |
| 753 | int err, old, new; |
| 754 | int *watchdog_param = (int *)table->data; |
| 755 | |
| 756 | mutex_lock(&watchdog_proc_mutex); |
| 757 | |
| 758 | /* |
| 759 | * If the parameter is being read return the state of the corresponding |
| 760 | * bit(s) in 'watchdog_enabled', else update 'watchdog_enabled' and the |
| 761 | * run state of the lockup detectors. |
| 762 | */ |
| 763 | if (!write) { |
| 764 | *watchdog_param = (watchdog_enabled & which) != 0; |
| 765 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| 766 | } else { |
| 767 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| 768 | if (err) |
| 769 | goto out; |
| 770 | |
| 771 | /* |
| 772 | * There is a race window between fetching the current value |
| 773 | * from 'watchdog_enabled' and storing the new value. During |
| 774 | * this race window, watchdog_nmi_enable() can sneak in and |
| 775 | * clear the NMI_WATCHDOG_ENABLED bit in 'watchdog_enabled'. |
| 776 | * The 'cmpxchg' detects this race and the loop retries. |
| 777 | */ |
| 778 | do { |
| 779 | old = watchdog_enabled; |
| 780 | /* |
| 781 | * If the parameter value is not zero set the |
| 782 | * corresponding bit(s), else clear it(them). |
| 783 | */ |
| 784 | if (*watchdog_param) |
| 785 | new = old | which; |
| 786 | else |
| 787 | new = old & ~which; |
| 788 | } while (cmpxchg(&watchdog_enabled, old, new) != old); |
| 789 | |
| 790 | /* |
| 791 | * Update the run state of the lockup detectors. |
| 792 | * Restore 'watchdog_enabled' on failure. |
| 793 | */ |
| 794 | err = proc_watchdog_update(); |
| 795 | if (err) |
| 796 | watchdog_enabled = old; |
| 797 | } |
| 798 | out: |
| 799 | mutex_unlock(&watchdog_proc_mutex); |
| 800 | return err; |
| 801 | } |
| 802 | |
| 803 | /* |
Ulrich Obergfell | 83a80a3 | 2015-04-14 15:44:08 -0700 | [diff] [blame] | 804 | * /proc/sys/kernel/watchdog |
| 805 | */ |
| 806 | int proc_watchdog(struct ctl_table *table, int write, |
| 807 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 808 | { |
| 809 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, |
| 810 | table, write, buffer, lenp, ppos); |
| 811 | } |
| 812 | |
| 813 | /* |
| 814 | * /proc/sys/kernel/nmi_watchdog |
| 815 | */ |
| 816 | int proc_nmi_watchdog(struct ctl_table *table, int write, |
| 817 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 818 | { |
| 819 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED, |
| 820 | table, write, buffer, lenp, ppos); |
| 821 | } |
| 822 | |
| 823 | /* |
| 824 | * /proc/sys/kernel/soft_watchdog |
| 825 | */ |
| 826 | int proc_soft_watchdog(struct ctl_table *table, int write, |
| 827 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 828 | { |
| 829 | return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, |
| 830 | table, write, buffer, lenp, ppos); |
| 831 | } |
| 832 | |
| 833 | /* |
| 834 | * /proc/sys/kernel/watchdog_thresh |
| 835 | */ |
| 836 | int proc_watchdog_thresh(struct ctl_table *table, int write, |
| 837 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 838 | { |
| 839 | int err, old; |
| 840 | |
| 841 | mutex_lock(&watchdog_proc_mutex); |
| 842 | |
| 843 | old = ACCESS_ONCE(watchdog_thresh); |
| 844 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| 845 | |
| 846 | if (err || !write) |
| 847 | goto out; |
| 848 | |
| 849 | /* |
| 850 | * Update the sample period. |
| 851 | * Restore 'watchdog_thresh' on failure. |
| 852 | */ |
| 853 | set_sample_period(); |
| 854 | err = proc_watchdog_update(); |
| 855 | if (err) |
| 856 | watchdog_thresh = old; |
| 857 | out: |
| 858 | mutex_unlock(&watchdog_proc_mutex); |
| 859 | return err; |
| 860 | } |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 861 | #endif /* CONFIG_SYSCTL */ |
| 862 | |
Peter Zijlstra | 004417a | 2010-11-25 18:38:29 +0100 | [diff] [blame] | 863 | void __init lockup_detector_init(void) |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 864 | { |
Chuansheng Liu | 0f34c40 | 2012-12-17 15:59:50 -0800 | [diff] [blame] | 865 | set_sample_period(); |
Frederic Weisbecker | b8900bc | 2013-06-06 15:42:53 +0200 | [diff] [blame] | 866 | |
Ulrich Obergfell | 195daf6 | 2015-04-14 15:44:13 -0700 | [diff] [blame] | 867 | if (watchdog_enabled) |
Ulrich Obergfell | b2f57c3 | 2015-04-14 15:44:16 -0700 | [diff] [blame^] | 868 | watchdog_enable_all_cpus(); |
Don Zickus | 58687ac | 2010-05-07 17:11:44 -0400 | [diff] [blame] | 869 | } |