libcfs/libcfs/watchdog.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * Copyright (C) 2004 Cluster File Systems, Inc.
   5  *   Author: Jacob Berkman <jacob@clusterfs.com>
   6  *
   7  *   This file is part of Lustre, http://www.lustre.org.
   8  *
   9  *   Lustre is free software; you can redistribute it and/or
  10  *   modify it under the terms of version 2 of the GNU General Public
  11  *   License as published by the Free Software Foundation.
  12  *
  13  *   Lustre is distributed in the hope that it will be useful,
  14  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *   GNU General Public License for more details.
  17  *
  18  *   You should have received a copy of the GNU General Public License
  19  *   along with Lustre; if not, write to the Free Software
  20  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23 #define DEBUG_SUBSYSTEM S_LNET
  24
  25 #include <libcfs/libcfs.h>
  26 #include "tracefile.h"
  27
  28 struct lc_watchdog {
  29         cfs_timer_t       lcw_timer; /* kernel timer */
  30         struct list_head  lcw_list;
  31         struct timeval    lcw_last_touched;
  32         cfs_task_t       *lcw_task;
  33
  34         void            (*lcw_callback)(pid_t, void *);
  35         void             *lcw_data;
  36
  37         pid_t             lcw_pid;
  38         cfs_duration_t    lcw_time; /* time until watchdog fires, jiffies */
  39
  40         enum {
  41                 LC_WATCHDOG_DISABLED,
  42                 LC_WATCHDOG_ENABLED,
  43                 LC_WATCHDOG_EXPIRED
  44         } lcw_state;
  45 };
  46
  47 #ifdef WITH_WATCHDOG
  48 /*
  49  * The dispatcher will complete lcw_start_completion when it starts,
  50  * and lcw_stop_completion when it exits.
  51  * Wake lcw_event_waitq to signal timer callback dispatches.
  52  */
  53 static struct completion lcw_start_completion;
  54 static struct completion lcw_stop_completion;
  55 static wait_queue_head_t lcw_event_waitq;
  56
  57 /*
  58  * Set this and wake lcw_event_waitq to stop the dispatcher.
  59  */
  60 enum {
  61         LCW_FLAG_STOP = 0
  62 };
  63 static unsigned long lcw_flags = 0;
  64
  65 /*
  66  * Number of outstanding watchdogs.
  67  * When it hits 1, we start the dispatcher.
  68  * When it hits 0, we stop the distpatcher.
  69  */
  70 static __u32         lcw_refcount = 0;
  71 static DECLARE_MUTEX(lcw_refcount_sem);
  72
  73 /*
  74  * List of timers that have fired that need their callbacks run by the
  75  * dispatcher.
  76  */
  77 static spinlock_t lcw_pending_timers_lock = SPIN_LOCK_UNLOCKED; /* BH lock! */
  78 static struct list_head lcw_pending_timers = \
  79         LIST_HEAD_INIT(lcw_pending_timers);
  80
  81 #ifdef HAVE_TASKLIST_LOCK
  82 static void
  83 lcw_dump(struct lc_watchdog *lcw)
  84 {
  85         cfs_task_t *tsk;
  86         ENTRY;
  87
  88         read_lock(&tasklist_lock);
  89         tsk = find_task_by_pid(lcw->lcw_pid);
  90
  91         if (tsk == NULL) {
  92                 CWARN("Process %d was not found in the task list; "
  93                       "watchdog callback may be incomplete\n", (int)lcw->lcw_pid);
  94         } else if (tsk != lcw->lcw_task) {
  95                 CWARN("The current process %d did not set the watchdog; "
  96                       "watchdog callback may be incomplete\n", (int)lcw->lcw_pid);
  97         } else {
  98                 libcfs_debug_dumpstack(tsk);
  99         }
 100
 101         read_unlock(&tasklist_lock);
 102         EXIT;
 103 }
 104 #else
 105 static void
 106 lcw_dump(struct lc_watchdog *lcw)
 107 {
 108         CERROR("unable to dump stack because of missing export\n");
 109 }
 110 #endif
 111
 112 static void lcw_cb(unsigned long data)
 113 {
 114         struct lc_watchdog *lcw = (struct lc_watchdog *)data;
 115
 116         ENTRY;
 117
 118         if (lcw->lcw_state != LC_WATCHDOG_ENABLED) {
 119                 EXIT;
 120                 return;
 121         }
 122
 123         lcw->lcw_state = LC_WATCHDOG_EXPIRED;
 124
 125         /* NB this warning should appear on the console, but may not get into
 126          * the logs since we're running in a softirq handler */
 127
 128         CWARN("Watchdog triggered for pid %d: it was inactive for %lds\n",
 129               (int)lcw->lcw_pid, cfs_duration_sec(lcw->lcw_time));
 130         lcw_dump(lcw);
 131
 132         spin_lock_bh(&lcw_pending_timers_lock);
 133
 134         if (list_empty(&lcw->lcw_list)) {
 135                 list_add(&lcw->lcw_list, &lcw_pending_timers);
 136                 wake_up(&lcw_event_waitq);
 137         }
 138
 139         spin_unlock_bh(&lcw_pending_timers_lock);
 140
 141         EXIT;
 142 }
 143
 144 static int is_watchdog_fired(void)
 145 {
 146         int rc;
 147
 148         if (test_bit(LCW_FLAG_STOP, &lcw_flags))
 149                 return 1;
 150
 151         spin_lock_bh(&lcw_pending_timers_lock);
 152         rc = !list_empty(&lcw_pending_timers);
 153         spin_unlock_bh(&lcw_pending_timers_lock);
 154         return rc;
 155 }
 156
 157 static int lcw_dispatch_main(void *data)
 158 {
 159         int                 rc = 0;
 160         unsigned long       flags;
 161         struct lc_watchdog *lcw;
 162
 163         ENTRY;
 164
 165         cfs_daemonize("lc_watchdogd");
 166
 167         SIGNAL_MASK_LOCK(current, flags);
 168         sigfillset(&current->blocked);
 169         RECALC_SIGPENDING;
 170         SIGNAL_MASK_UNLOCK(current, flags);
 171
 172         complete(&lcw_start_completion);
 173
 174         while (1) {
 175                 wait_event_interruptible(lcw_event_waitq, is_watchdog_fired());
 176                 CDEBUG(D_INFO, "Watchdog got woken up...\n");
 177                 if (test_bit(LCW_FLAG_STOP, &lcw_flags)) {
 178                         CDEBUG(D_INFO, "LCW_FLAG_STOP was set, shutting down...\n");
 179
 180                         spin_lock_bh(&lcw_pending_timers_lock);
 181                         rc = !list_empty(&lcw_pending_timers);
 182                         spin_unlock_bh(&lcw_pending_timers_lock);
 183                         if (rc) {
 184                                 CERROR("pending timers list was not empty at "
 185                                        "time of watchdog dispatch shutdown\n");
 186                         }
 187                         break;
 188                 }
 189
 190                 spin_lock_bh(&lcw_pending_timers_lock);
 191                 while (!list_empty(&lcw_pending_timers)) {
 192
 193                         lcw = list_entry(lcw_pending_timers.next,
 194                                          struct lc_watchdog,
 195                                          lcw_list);
 196                         list_del_init(&lcw->lcw_list);
 197                         spin_unlock_bh(&lcw_pending_timers_lock);
 198
 199                         CDEBUG(D_INFO, "found lcw for pid %d: inactive for "
 200                                "%lds\n", (int)lcw->lcw_pid,
 201                                cfs_duration_sec(lcw->lcw_time));
 202
 203                         if (lcw->lcw_state != LC_WATCHDOG_DISABLED)
 204                                 lcw->lcw_callback(lcw->lcw_pid, lcw->lcw_data);
 205
 206                         spin_lock_bh(&lcw_pending_timers_lock);
 207                 }
 208                 spin_unlock_bh(&lcw_pending_timers_lock);
 209         }
 210
 211         complete(&lcw_stop_completion);
 212
 213         RETURN(rc);
 214 }
 215
 216 static void lcw_dispatch_start(void)
 217 {
 218         int rc;
 219
 220         ENTRY;
 221         LASSERT(lcw_refcount == 1);
 222
 223         init_completion(&lcw_stop_completion);
 224         init_completion(&lcw_start_completion);
 225         init_waitqueue_head(&lcw_event_waitq);
 226
 227         CDEBUG(D_INFO, "starting dispatch thread\n");
 228         rc = kernel_thread(lcw_dispatch_main, NULL, 0);
 229         if (rc < 0) {
 230                 CERROR("error spawning watchdog dispatch thread: %d\n", rc);
 231                 EXIT;
 232                 return;
 233         }
 234         wait_for_completion(&lcw_start_completion);
 235         CDEBUG(D_INFO, "watchdog dispatcher initialization complete.\n");
 236
 237         EXIT;
 238 }
 239
 240 static void lcw_dispatch_stop(void)
 241 {
 242         ENTRY;
 243         LASSERT(lcw_refcount == 0);
 244
 245         CDEBUG(D_INFO, "trying to stop watchdog dispatcher.\n");
 246
 247         set_bit(LCW_FLAG_STOP, &lcw_flags);
 248         wake_up(&lcw_event_waitq);
 249
 250         wait_for_completion(&lcw_stop_completion);
 251
 252         CDEBUG(D_INFO, "watchdog dispatcher has shut down.\n");
 253
 254         EXIT;
 255 }
 256
 257 struct lc_watchdog *lc_watchdog_add(int timeout_ms,
 258                                     void (*callback)(pid_t, void *),
 259                                     void *data)
 260 {
 261         struct lc_watchdog *lcw = NULL;
 262         ENTRY;
 263
 264         LIBCFS_ALLOC(lcw, sizeof(*lcw));
 265         if (lcw == NULL) {
 266                 CDEBUG(D_INFO, "Could not allocate new lc_watchdog\n");
 267                 RETURN(ERR_PTR(-ENOMEM));
 268         }
 269
 270         lcw->lcw_task     = cfs_current();
 271         lcw->lcw_pid      = cfs_curproc_pid();
 272         lcw->lcw_time     = cfs_time_seconds(timeout_ms) / 1000;
 273         lcw->lcw_callback = (callback != NULL) ? callback : lc_watchdog_dumplog;
 274         lcw->lcw_data     = data;
 275         lcw->lcw_state    = LC_WATCHDOG_DISABLED;
 276
 277         INIT_LIST_HEAD(&lcw->lcw_list);
 278
 279         lcw->lcw_timer.function = lcw_cb;
 280         lcw->lcw_timer.data = (unsigned long)lcw;
 281         lcw->lcw_timer.expires = jiffies + lcw->lcw_time;
 282         init_timer(&lcw->lcw_timer);
 283
 284         down(&lcw_refcount_sem);
 285         if (++lcw_refcount == 1)
 286                 lcw_dispatch_start();
 287         up(&lcw_refcount_sem);
 288
 289         /* Keep this working in case we enable them by default */
 290         if (lcw->lcw_state == LC_WATCHDOG_ENABLED) {
 291                 do_gettimeofday(&lcw->lcw_last_touched);
 292                 add_timer(&lcw->lcw_timer);
 293         }
 294
 295         RETURN(lcw);
 296 }
 297 EXPORT_SYMBOL(lc_watchdog_add);
 298
 299 static void lcw_update_time(struct lc_watchdog *lcw, const char *message)
 300 {
 301         struct timeval newtime;
 302         struct timeval timediff;
 303
 304         do_gettimeofday(&newtime);
 305         if (lcw->lcw_state == LC_WATCHDOG_EXPIRED) {
 306                 cfs_timeval_sub(&newtime, &lcw->lcw_last_touched, &timediff);
 307                 CWARN("Expired watchdog for pid %d %s after %lu.%.4lus\n",
 308                       lcw->lcw_pid,
 309                       message,
 310                       timediff.tv_sec,
 311                       timediff.tv_usec / 100);
 312         }
 313         lcw->lcw_last_touched = newtime;
 314 }
 315
 316 void lc_watchdog_touch_ms(struct lc_watchdog *lcw, int timeout_ms)
 317 {
 318         ENTRY;
 319         LASSERT(lcw != NULL);
 320
 321         spin_lock_bh(&lcw_pending_timers_lock);
 322         list_del_init(&lcw->lcw_list);
 323         spin_unlock_bh(&lcw_pending_timers_lock);
 324
 325         lcw_update_time(lcw, "touched");
 326         lcw->lcw_state = LC_WATCHDOG_ENABLED;
 327
 328         mod_timer(&lcw->lcw_timer, jiffies +
 329                   cfs_time_seconds(timeout_ms) / 1000);
 330
 331         EXIT;
 332 }
 333 EXPORT_SYMBOL(lc_watchdog_touch_ms);
 334
 335 /* deprecated - use above instead */
 336 void lc_watchdog_touch(struct lc_watchdog *lcw)
 337 {
 338         lc_watchdog_touch_ms(lcw, cfs_duration_sec(lcw->lcw_time) * 1000);
 339 }
 340 EXPORT_SYMBOL(lc_watchdog_touch);
 341
 342 void lc_watchdog_disable(struct lc_watchdog *lcw)
 343 {
 344         ENTRY;
 345         LASSERT(lcw != NULL);
 346
 347         spin_lock_bh(&lcw_pending_timers_lock);
 348         if (!list_empty(&lcw->lcw_list))
 349                 list_del_init(&lcw->lcw_list);
 350         spin_unlock_bh(&lcw_pending_timers_lock);
 351
 352         lcw_update_time(lcw, "disabled");
 353         lcw->lcw_state = LC_WATCHDOG_DISABLED;
 354
 355         EXIT;
 356 }
 357 EXPORT_SYMBOL(lc_watchdog_disable);
 358
 359 void lc_watchdog_delete(struct lc_watchdog *lcw)
 360 {
 361         ENTRY;
 362         LASSERT(lcw != NULL);
 363
 364         del_timer(&lcw->lcw_timer);
 365
 366         lcw_update_time(lcw, "deleted");
 367
 368         spin_lock_bh(&lcw_pending_timers_lock);
 369         if (!list_empty(&lcw->lcw_list))
 370                 list_del_init(&lcw->lcw_list);
 371         spin_unlock_bh(&lcw_pending_timers_lock);
 372
 373         down(&lcw_refcount_sem);
 374         if (--lcw_refcount == 0)
 375                 lcw_dispatch_stop();
 376         up(&lcw_refcount_sem);
 377
 378         LIBCFS_FREE(lcw, sizeof(*lcw));
 379
 380         EXIT;
 381 }
 382 EXPORT_SYMBOL(lc_watchdog_delete);
 383
 384 /*
 385  * Provided watchdog handlers
 386  */
 387
 388 void lc_watchdog_dumplog(pid_t pid, void *data)
 389 {
 390         libcfs_debug_dumplog_internal((void *)((unsigned long)pid));
 391 }
 392 EXPORT_SYMBOL(lc_watchdog_dumplog);
 393
 394 #else   /* !defined(WITH_WATCHDOG) */
 395
 396 struct lc_watchdog *lc_watchdog_add(int timeout_ms,
 397                                     void (*callback)(pid_t pid, void *),
 398                                     void *data)
 399 {
 400         static struct lc_watchdog      watchdog;
 401         return &watchdog;
 402 }
 403 EXPORT_SYMBOL(lc_watchdog_add);
 404
 405 void lc_watchdog_touch_ms(struct lc_watchdog *lcw, int timeout_ms)
 406 {
 407 }
 408 EXPORT_SYMBOL(lc_watchdog_touch_ms);
 409
 410 void lc_watchdog_touch(struct lc_watchdog *lcw)
 411 {
 412 }
 413 EXPORT_SYMBOL(lc_watchdog_touch);
 414
 415 void lc_watchdog_disable(struct lc_watchdog *lcw)
 416 {
 417 }
 418 EXPORT_SYMBOL(lc_watchdog_disable);
 419
 420 void lc_watchdog_delete(struct lc_watchdog *lcw)
 421 {
 422 }
 423 EXPORT_SYMBOL(lc_watchdog_delete);
 424
 425 #endif
 426