libcfs/libcfs/watchdog.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2012, 2014, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * libcfs/libcfs/watchdog.c
  37  *
  38  * Author: Jacob Berkman <jacob@clusterfs.com>
  39  */
  40
  41 #define DEBUG_SUBSYSTEM S_LNET
  42
  43 #include <linux/kthread.h>
  44 #include <libcfs/libcfs.h>
  45 #include "tracefile.h"
  46
  47 struct lc_watchdog {
  48         spinlock_t              lcw_lock;       /* check or change lcw_list */
  49         int                     lcw_refcount;   /* must hold lcw_pending_timers_lock */
  50         struct timer_list       lcw_timer;      /* kernel timer */
  51         struct list_head        lcw_list;       /* chain on pending list */
  52         cfs_time_t              lcw_last_touched;/* last touched stamp */
  53         struct task_struct     *lcw_task;       /* owner task */
  54         void                    (*lcw_callback)(pid_t, void *);
  55         void                    *lcw_data;
  56
  57         pid_t                   lcw_pid;
  58
  59         enum {
  60                 LC_WATCHDOG_DISABLED,
  61                 LC_WATCHDOG_ENABLED,
  62                 LC_WATCHDOG_EXPIRED
  63         } lcw_state;
  64 };
  65
  66 #ifdef WITH_WATCHDOG
  67 /*
  68  * The dispatcher will complete lcw_start_completion when it starts,
  69  * and lcw_stop_completion when it exits.
  70  * Wake lcw_event_waitq to signal timer callback dispatches.
  71  */
  72 static struct completion lcw_start_completion;
  73 static struct completion  lcw_stop_completion;
  74 static wait_queue_head_t lcw_event_waitq;
  75
  76 /*
  77  * Set this and wake lcw_event_waitq to stop the dispatcher.
  78  */
  79 enum {
  80         LCW_FLAG_STOP = 0
  81 };
  82 static unsigned long lcw_flags = 0;
  83
  84 /*
  85  * Number of outstanding watchdogs.
  86  * When it hits 1, we start the dispatcher.
  87  * When it hits 0, we stop the dispatcher.
  88  */
  89 static __u32         lcw_refcount = 0;
  90 static DEFINE_MUTEX(lcw_refcount_mutex);
  91
  92 /*
  93  * List of timers that have fired that need their callbacks run by the
  94  * dispatcher.
  95  */
  96 /* BH lock! */
  97 static DEFINE_SPINLOCK(lcw_pending_timers_lock);
  98 static struct list_head lcw_pending_timers = LIST_HEAD_INIT(lcw_pending_timers);
  99
 100 /* Last time a watchdog expired */
 101 static cfs_time_t lcw_last_watchdog_time;
 102 static int lcw_recent_watchdog_count;
 103
 104 static void
 105 lcw_dump(struct lc_watchdog *lcw)
 106 {
 107         ENTRY;
 108         rcu_read_lock();
 109        if (lcw->lcw_task == NULL) {
 110                 LCONSOLE_WARN("Process " LPPID " was not found in the task "
 111                               "list; watchdog callback may be incomplete\n",
 112                               (int)lcw->lcw_pid);
 113         } else {
 114                 libcfs_debug_dumpstack(lcw->lcw_task);
 115         }
 116
 117         rcu_read_unlock();
 118         EXIT;
 119 }
 120
 121 static void lcw_cb(ulong_ptr_t data)
 122 {
 123         struct lc_watchdog *lcw = (struct lc_watchdog *)data;
 124         ENTRY;
 125
 126         if (lcw->lcw_state != LC_WATCHDOG_ENABLED) {
 127                 EXIT;
 128                 return;
 129         }
 130
 131         lcw->lcw_state = LC_WATCHDOG_EXPIRED;
 132
 133         spin_lock_bh(&lcw->lcw_lock);
 134         LASSERT(list_empty(&lcw->lcw_list));
 135
 136         spin_lock_bh(&lcw_pending_timers_lock);
 137         lcw->lcw_refcount++; /* +1 for pending list */
 138         list_add(&lcw->lcw_list, &lcw_pending_timers);
 139         wake_up(&lcw_event_waitq);
 140
 141         spin_unlock_bh(&lcw_pending_timers_lock);
 142         spin_unlock_bh(&lcw->lcw_lock);
 143         EXIT;
 144 }
 145
 146 static int is_watchdog_fired(void)
 147 {
 148         int rc;
 149
 150         if (test_bit(LCW_FLAG_STOP, &lcw_flags))
 151                 return 1;
 152
 153         spin_lock_bh(&lcw_pending_timers_lock);
 154         rc = !list_empty(&lcw_pending_timers);
 155         spin_unlock_bh(&lcw_pending_timers_lock);
 156         return rc;
 157 }
 158
 159 static void lcw_dump_stack(struct lc_watchdog *lcw)
 160 {
 161         cfs_time_t      current_time;
 162         cfs_duration_t  delta_time;
 163         struct timeval  timediff;
 164
 165         current_time = cfs_time_current();
 166         delta_time = cfs_time_sub(current_time, lcw->lcw_last_touched);
 167         cfs_duration_usec(delta_time, &timediff);
 168
 169         /*
 170          * Check to see if we should throttle the watchdog timer to avoid
 171          * too many dumps going to the console thus triggering an NMI.
 172          */
 173         delta_time = cfs_duration_sec(cfs_time_sub(current_time,
 174                                                    lcw_last_watchdog_time));
 175
 176         if (delta_time < libcfs_watchdog_ratelimit &&
 177             lcw_recent_watchdog_count > 3) {
 178                 LCONSOLE_WARN("Service thread pid %u was inactive for "
 179                               "%lu.%.02lus. Watchdog stack traces are limited "
 180                               "to 3 per %d seconds, skipping this one.\n",
 181                               (int)lcw->lcw_pid,
 182                               timediff.tv_sec,
 183                               timediff.tv_usec / 10000,
 184                               libcfs_watchdog_ratelimit);
 185         } else {
 186                 if (delta_time < libcfs_watchdog_ratelimit) {
 187                         lcw_recent_watchdog_count++;
 188                 } else {
 189                         memcpy(&lcw_last_watchdog_time, &current_time,
 190                                sizeof(current_time));
 191                         lcw_recent_watchdog_count = 0;
 192                 }
 193
 194                 LCONSOLE_WARN("Service thread pid %u was inactive for "
 195                               "%lu.%.02lus. The thread might be hung, or it "
 196                               "might only be slow and will resume later. "
 197                               "Dumping the stack trace for debugging purposes:"
 198                               "\n",
 199                               (int)lcw->lcw_pid,
 200                               timediff.tv_sec,
 201                               timediff.tv_usec / 10000);
 202                 lcw_dump(lcw);
 203         }
 204 }
 205
 206 static int lcw_dispatch_main(void *data)
 207 {
 208         int                 rc = 0;
 209         struct lc_watchdog *lcw;
 210         struct list_head zombies = LIST_HEAD_INIT(zombies);
 211
 212         ENTRY;
 213
 214         complete(&lcw_start_completion);
 215
 216         while (1) {
 217                 int dumplog = 1;
 218
 219                 rc = wait_event_interruptible(lcw_event_waitq,
 220                                               is_watchdog_fired());
 221                 CDEBUG(D_INFO, "Watchdog got woken up...\n");
 222                 if (test_bit(LCW_FLAG_STOP, &lcw_flags)) {
 223                         CDEBUG(D_INFO, "LCW_FLAG_STOP set, shutting down...\n");
 224
 225                         spin_lock_bh(&lcw_pending_timers_lock);
 226                         rc = !list_empty(&lcw_pending_timers);
 227                         spin_unlock_bh(&lcw_pending_timers_lock);
 228                         if (rc) {
 229                                 CERROR("pending timers list was not empty at "
 230                                        "time of watchdog dispatch shutdown\n");
 231                         }
 232                         break;
 233                 }
 234
 235                 spin_lock_bh(&lcw_pending_timers_lock);
 236                 while (!list_empty(&lcw_pending_timers)) {
 237                         int is_dumplog;
 238
 239                         lcw = list_entry(lcw_pending_timers.next,
 240                                          struct lc_watchdog, lcw_list);
 241                         /* +1 ref for callback to make sure lwc wouldn't be
 242                          * deleted after releasing lcw_pending_timers_lock */
 243                         lcw->lcw_refcount++;
 244                         spin_unlock_bh(&lcw_pending_timers_lock);
 245
 246                         /* lock ordering */
 247                         spin_lock_bh(&lcw->lcw_lock);
 248                         spin_lock_bh(&lcw_pending_timers_lock);
 249
 250                         if (list_empty(&lcw->lcw_list)) {
 251                                 /* already removed from pending list */
 252                                 lcw->lcw_refcount--; /* -1 ref for callback */
 253                                 if (lcw->lcw_refcount == 0)
 254                                         list_add(&lcw->lcw_list, &zombies);
 255                                 spin_unlock_bh(&lcw->lcw_lock);
 256                                 /* still hold lcw_pending_timers_lock */
 257                                 continue;
 258                         }
 259
 260                         list_del_init(&lcw->lcw_list);
 261                         lcw->lcw_refcount--; /* -1 ref for pending list */
 262
 263                         spin_unlock_bh(&lcw_pending_timers_lock);
 264                         spin_unlock_bh(&lcw->lcw_lock);
 265
 266                         CDEBUG(D_INFO, "found lcw for pid " LPPID "\n",
 267                                lcw->lcw_pid);
 268                         lcw_dump_stack(lcw);
 269
 270                         is_dumplog = lcw->lcw_callback == lc_watchdog_dumplog;
 271                         if (lcw->lcw_state != LC_WATCHDOG_DISABLED &&
 272                             (dumplog || !is_dumplog)) {
 273                                 lcw->lcw_callback(lcw->lcw_pid, lcw->lcw_data);
 274                                 if (dumplog && is_dumplog)
 275                                         dumplog = 0;
 276                         }
 277
 278                         spin_lock_bh(&lcw_pending_timers_lock);
 279                         lcw->lcw_refcount--; /* -1 ref for callback */
 280                         if (lcw->lcw_refcount == 0)
 281                                 list_add(&lcw->lcw_list, &zombies);
 282                 }
 283                 spin_unlock_bh(&lcw_pending_timers_lock);
 284
 285                 while (!list_empty(&zombies)) {
 286                         lcw = list_entry(zombies.next,
 287                                              struct lc_watchdog, lcw_list);
 288                         list_del_init(&lcw->lcw_list);
 289                         LIBCFS_FREE(lcw, sizeof(*lcw));
 290                 }
 291         }
 292
 293         complete(&lcw_stop_completion);
 294
 295         RETURN(rc);
 296 }
 297
 298 static void lcw_dispatch_start(void)
 299 {
 300         struct task_struct *task;
 301
 302         ENTRY;
 303         LASSERT(lcw_refcount == 1);
 304
 305         init_completion(&lcw_stop_completion);
 306         init_completion(&lcw_start_completion);
 307         init_waitqueue_head(&lcw_event_waitq);
 308
 309         CDEBUG(D_INFO, "starting dispatch thread\n");
 310         task = kthread_run(lcw_dispatch_main, NULL, "lc_watchdogd");
 311         if (IS_ERR(task)) {
 312                 CERROR("error spawning watchdog dispatch thread: %ld\n",
 313                         PTR_ERR(task));
 314                 EXIT;
 315                 return;
 316         }
 317         wait_for_completion(&lcw_start_completion);
 318         CDEBUG(D_INFO, "watchdog dispatcher initialization complete.\n");
 319
 320         EXIT;
 321 }
 322
 323 static void lcw_dispatch_stop(void)
 324 {
 325         ENTRY;
 326         LASSERT(lcw_refcount == 0);
 327
 328         CDEBUG(D_INFO, "trying to stop watchdog dispatcher.\n");
 329
 330         set_bit(LCW_FLAG_STOP, &lcw_flags);
 331         wake_up(&lcw_event_waitq);
 332
 333         wait_for_completion(&lcw_stop_completion);
 334
 335         CDEBUG(D_INFO, "watchdog dispatcher has shut down.\n");
 336
 337         EXIT;
 338 }
 339
 340 struct lc_watchdog *lc_watchdog_add(int timeout,
 341                                     void (*callback)(pid_t, void *),
 342                                     void *data)
 343 {
 344         struct lc_watchdog *lcw = NULL;
 345         ENTRY;
 346
 347         LIBCFS_ALLOC(lcw, sizeof(*lcw));
 348         if (lcw == NULL) {
 349                 CDEBUG(D_INFO, "Could not allocate new lc_watchdog\n");
 350                 RETURN(ERR_PTR(-ENOMEM));
 351         }
 352
 353         spin_lock_init(&lcw->lcw_lock);
 354         lcw->lcw_refcount = 1; /* refcount for owner */
 355         lcw->lcw_task     = current;
 356         lcw->lcw_pid      = current_pid();
 357         lcw->lcw_callback = (callback != NULL) ? callback : lc_watchdog_dumplog;
 358         lcw->lcw_data     = data;
 359         lcw->lcw_state    = LC_WATCHDOG_DISABLED;
 360
 361         INIT_LIST_HEAD(&lcw->lcw_list);
 362         cfs_timer_init(&lcw->lcw_timer, lcw_cb, lcw);
 363
 364         mutex_lock(&lcw_refcount_mutex);
 365         if (++lcw_refcount == 1)
 366                 lcw_dispatch_start();
 367         mutex_unlock(&lcw_refcount_mutex);
 368
 369         /* Keep this working in case we enable them by default */
 370         if (lcw->lcw_state == LC_WATCHDOG_ENABLED) {
 371                 lcw->lcw_last_touched = cfs_time_current();
 372                 cfs_timer_arm(&lcw->lcw_timer, cfs_time_seconds(timeout) +
 373                               cfs_time_current());
 374         }
 375
 376         RETURN(lcw);
 377 }
 378 EXPORT_SYMBOL(lc_watchdog_add);
 379
 380 static void lcw_update_time(struct lc_watchdog *lcw, const char *message)
 381 {
 382         cfs_time_t newtime = cfs_time_current();
 383
 384         if (lcw->lcw_state == LC_WATCHDOG_EXPIRED) {
 385                 struct timeval timediff;
 386                 cfs_time_t delta_time = cfs_time_sub(newtime,
 387                                                      lcw->lcw_last_touched);
 388                 cfs_duration_usec(delta_time, &timediff);
 389
 390                 LCONSOLE_WARN("Service thread pid %u %s after %lu.%.02lus. "
 391                               "This indicates the system was overloaded (too "
 392                               "many service threads, or there were not enough "
 393                               "hardware resources).\n",
 394                               lcw->lcw_pid,
 395                               message,
 396                               timediff.tv_sec,
 397                               timediff.tv_usec / 10000);
 398         }
 399         lcw->lcw_last_touched = newtime;
 400 }
 401
 402 static void lc_watchdog_del_pending(struct lc_watchdog *lcw)
 403 {
 404         spin_lock_bh(&lcw->lcw_lock);
 405         if (unlikely(!list_empty(&lcw->lcw_list))) {
 406                 spin_lock_bh(&lcw_pending_timers_lock);
 407                 list_del_init(&lcw->lcw_list);
 408                 lcw->lcw_refcount--; /* -1 ref for pending list */
 409                 spin_unlock_bh(&lcw_pending_timers_lock);
 410         }
 411
 412         spin_unlock_bh(&lcw->lcw_lock);
 413 }
 414
 415 void lc_watchdog_touch(struct lc_watchdog *lcw, int timeout)
 416 {
 417         ENTRY;
 418         LASSERT(lcw != NULL);
 419
 420         lc_watchdog_del_pending(lcw);
 421
 422         lcw_update_time(lcw, "resumed");
 423
 424         cfs_timer_arm(&lcw->lcw_timer, cfs_time_current() +
 425                       cfs_time_seconds(timeout));
 426         lcw->lcw_state = LC_WATCHDOG_ENABLED;
 427
 428         EXIT;
 429 }
 430 EXPORT_SYMBOL(lc_watchdog_touch);
 431
 432 void lc_watchdog_disable(struct lc_watchdog *lcw)
 433 {
 434         ENTRY;
 435         LASSERT(lcw != NULL);
 436
 437         lc_watchdog_del_pending(lcw);
 438
 439         lcw_update_time(lcw, "completed");
 440         lcw->lcw_state = LC_WATCHDOG_DISABLED;
 441
 442         EXIT;
 443 }
 444 EXPORT_SYMBOL(lc_watchdog_disable);
 445
 446 void lc_watchdog_delete(struct lc_watchdog *lcw)
 447 {
 448         int dead;
 449
 450         ENTRY;
 451         LASSERT(lcw != NULL);
 452
 453         cfs_timer_disarm(&lcw->lcw_timer);
 454
 455         lcw_update_time(lcw, "stopped");
 456
 457         spin_lock_bh(&lcw->lcw_lock);
 458         spin_lock_bh(&lcw_pending_timers_lock);
 459         if (unlikely(!list_empty(&lcw->lcw_list))) {
 460                 list_del_init(&lcw->lcw_list);
 461                 lcw->lcw_refcount--; /* -1 ref for pending list */
 462         }
 463
 464         lcw->lcw_refcount--; /* -1 ref for owner */
 465         dead = lcw->lcw_refcount == 0;
 466         spin_unlock_bh(&lcw_pending_timers_lock);
 467         spin_unlock_bh(&lcw->lcw_lock);
 468
 469         if (dead)
 470                 LIBCFS_FREE(lcw, sizeof(*lcw));
 471
 472         mutex_lock(&lcw_refcount_mutex);
 473         if (--lcw_refcount == 0)
 474                 lcw_dispatch_stop();
 475         mutex_unlock(&lcw_refcount_mutex);
 476
 477         EXIT;
 478 }
 479 EXPORT_SYMBOL(lc_watchdog_delete);
 480
 481 /*
 482  * Provided watchdog handlers
 483  */
 484
 485 void lc_watchdog_dumplog(pid_t pid, void *data)
 486 {
 487         libcfs_debug_dumplog_internal((void *)((long_ptr_t)pid));
 488 }
 489 EXPORT_SYMBOL(lc_watchdog_dumplog);
 490
 491 #else   /* !defined(WITH_WATCHDOG) */
 492
 493 struct lc_watchdog *lc_watchdog_add(int timeout,
 494                                     void (*callback)(pid_t pid, void *),
 495                                     void *data)
 496 {
 497         static struct lc_watchdog      watchdog;
 498         return &watchdog;
 499 }
 500 EXPORT_SYMBOL(lc_watchdog_add);
 501
 502 void lc_watchdog_touch(struct lc_watchdog *lcw, int timeout)
 503 {
 504 }
 505 EXPORT_SYMBOL(lc_watchdog_touch);
 506
 507 void lc_watchdog_disable(struct lc_watchdog *lcw)
 508 {
 509 }
 510 EXPORT_SYMBOL(lc_watchdog_disable);
 511
 512 void lc_watchdog_delete(struct lc_watchdog *lcw)
 513 {
 514 }
 515 EXPORT_SYMBOL(lc_watchdog_delete);
 516
 517 #endif