lnet/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_PORTALS
  24
  25 #include <libcfs/kp30.h>
  26 #include <libcfs/libcfs.h>
  27 #include <libcfs/linux/portals_compat25.h>
  28
  29
  30
  31 struct lc_watchdog {
  32         struct timer_list lcw_timer; /* kernel timer */
  33         struct list_head  lcw_list;
  34         struct timeval    lcw_last_touched;
  35         struct task_struct *lcw_task;
  36
  37         void (*lcw_callback)(struct lc_watchdog *,
  38                              struct task_struct *,
  39                              void *data);
  40         void *lcw_data;
  41
  42         int lcw_pid;
  43         int lcw_time; /* time until watchdog fires, in ms */
  44
  45         enum {
  46                 LC_WATCHDOG_DISABLED,
  47                 LC_WATCHDOG_ENABLED,
  48                 LC_WATCHDOG_EXPIRED
  49         } lcw_state;
  50 };
  51
  52 /*
  53  * The dispatcher will complete lcw_start_completion when it starts,
  54  * and lcw_stop_completion when it exits.
  55  * Wake lcw_event_waitq to signal timer callback dispatches.
  56  */
  57 static struct completion lcw_start_completion;
  58 static struct completion lcw_stop_completion;
  59 static wait_queue_head_t lcw_event_waitq;
  60
  61 /*
  62  * Set this and wake lcw_event_waitq to stop the dispatcher.
  63  */
  64 enum {
  65         LCW_FLAG_STOP = 0
  66 };
  67 static unsigned long lcw_flags = 0;
  68
  69 /*
  70  * Number of outstanding watchdogs.
  71  * When it hits 1, we start the dispatcher.
  72  * When it hits 0, we stop the distpatcher.
  73  */
  74 static __u32         lcw_refcount = 0;
  75 static DECLARE_MUTEX(lcw_refcount_sem);
  76
  77 /*
  78  * List of timers that have fired that need their callbacks run by the
  79  * dispatcher.
  80  */
  81 static spinlock_t       lcw_pending_timers_lock = SPIN_LOCK_UNLOCKED;
  82 static struct list_head lcw_pending_timers = \
  83         LIST_HEAD_INIT(lcw_pending_timers);
  84
  85 static struct task_struct *lcw_lookup_task(struct lc_watchdog *lcw)
  86 {
  87         struct task_struct *tsk;
  88         unsigned long flags;
  89         ENTRY;
  90
  91         read_lock_irqsave(&tasklist_lock, flags);
  92         tsk = find_task_by_pid(lcw->lcw_pid);
  93         read_unlock_irqrestore(&tasklist_lock, flags);
  94         if (!tsk) {
  95                 CWARN("Process %d was not found in the task list; "
  96                       "watchdog callback may be incomplete\n", lcw->lcw_pid);
  97         } else if (tsk != lcw->lcw_task) {
  98                 tsk = NULL;
  99                 CWARN("The current process %d did not set the watchdog; "
 100                       "watchdog callback may be incomplete\n", lcw->lcw_pid);
 101         }
 102
 103         RETURN(tsk);
 104 }
 105
 106 static void lcw_cb(unsigned long data)
 107 {
 108         struct lc_watchdog *lcw = (struct lc_watchdog *)data;
 109         struct task_struct *tsk;
 110         unsigned long flags;
 111
 112         ENTRY;
 113
 114         if (lcw->lcw_state != LC_WATCHDOG_ENABLED) {
 115                 EXIT;
 116                 return;
 117         }
 118
 119         lcw->lcw_state = LC_WATCHDOG_EXPIRED;
 120
 121         CWARN("Watchdog triggered for pid %d: it was inactive for %dms\n",
 122               lcw->lcw_pid, (lcw->lcw_time * 1000) / HZ);
 123
 124         tsk = lcw_lookup_task(lcw);
 125         if (tsk != NULL)
 126                 portals_debug_dumpstack(tsk);
 127
 128         spin_lock_irqsave(&lcw_pending_timers_lock, flags);
 129         if (list_empty(&lcw->lcw_list)) {
 130                 list_add(&lcw->lcw_list, &lcw_pending_timers);
 131                 wake_up(&lcw_event_waitq);
 132         }
 133         spin_unlock_irqrestore(&lcw_pending_timers_lock, flags);
 134
 135         EXIT;
 136 }
 137
 138 static int is_watchdog_fired(void)
 139 {
 140         unsigned long flags;
 141         int rc;
 142
 143         if (test_bit(LCW_FLAG_STOP, &lcw_flags))
 144                 return 1;
 145
 146         spin_lock_irqsave(&lcw_pending_timers_lock, flags);
 147         rc = !list_empty(&lcw_pending_timers);
 148         spin_unlock_irqrestore(&lcw_pending_timers_lock, flags);
 149         return rc;
 150 }
 151
 152 static int lcw_dispatch_main(void *data)
 153 {
 154         int rc = 0;
 155         unsigned long flags;
 156         struct lc_watchdog *lcw;
 157         struct task_struct *tsk;
 158
 159         ENTRY;
 160
 161         kportal_daemonize("lc_watchdogd");
 162
 163         SIGNAL_MASK_LOCK(current, flags);
 164         sigfillset(&current->blocked);
 165         RECALC_SIGPENDING;
 166         SIGNAL_MASK_UNLOCK(current, flags);
 167
 168         complete(&lcw_start_completion);
 169
 170         while (1) {
 171                 wait_event_interruptible(lcw_event_waitq, is_watchdog_fired());
 172                 CDEBUG(D_INFO, "Watchdog got woken up...\n");
 173                 if (test_bit(LCW_FLAG_STOP, &lcw_flags)) {
 174                         CDEBUG(D_INFO, "LCW_FLAG_STOP was set, shutting down...\n");
 175
 176                         spin_lock_irqsave(&lcw_pending_timers_lock, flags);
 177                         rc = !list_empty(&lcw_pending_timers);
 178                         spin_unlock_irqrestore(&lcw_pending_timers_lock, flags);
 179                         if (rc) {
 180                                 CERROR("pending timers list was not empty at "
 181                                        "time of watchdog dispatch shutdown\n");
 182                         }
 183                         break;
 184                 }
 185
 186                 spin_lock_irqsave(&lcw_pending_timers_lock, flags);
 187                 while (!list_empty(&lcw_pending_timers)) {
 188
 189                         lcw = list_entry(lcw_pending_timers.next,
 190                                          struct lc_watchdog,
 191                                          lcw_list);
 192                         list_del_init(&lcw->lcw_list);
 193                         spin_unlock_irqrestore(&lcw_pending_timers_lock, flags);
 194
 195                         CDEBUG(D_INFO, "found lcw for pid %d\n", lcw->lcw_pid);
 196
 197                         if (lcw->lcw_state != LC_WATCHDOG_DISABLED) {
 198                                 /*
 199                                  * sanity check the task against our
 200                                  * watchdog
 201                                  */
 202                                 tsk = lcw_lookup_task(lcw);
 203                                 lcw->lcw_callback(lcw, tsk, lcw->lcw_data);
 204                         }
 205
 206                         spin_lock_irqsave(&lcw_pending_timers_lock, flags);
 207                 }
 208                 spin_unlock_irqrestore(&lcw_pending_timers_lock, flags);
 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)(struct lc_watchdog *,
 259                                                      struct task_struct *,
 260                                                      void *),
 261                                     void *data)
 262 {
 263         struct lc_watchdog *lcw = NULL;
 264         ENTRY;
 265
 266         PORTAL_ALLOC(lcw, sizeof(*lcw));
 267         if (!lcw) {
 268                 CDEBUG(D_INFO, "Could not allocate new lc_watchdog\n");
 269                 RETURN(ERR_PTR(-ENOMEM));
 270         }
 271
 272         lcw->lcw_task = cfs_current();
 273         lcw->lcw_pid = cfs_curproc_pid();
 274         lcw->lcw_time = (timeout_ms * HZ) / 1000;
 275         lcw->lcw_callback = callback ? callback : lc_watchdog_dumplog;
 276         lcw->lcw_data = data;
 277         lcw->lcw_state = LC_WATCHDOG_DISABLED;
 278
 279         INIT_LIST_HEAD(&lcw->lcw_list);
 280
 281         lcw->lcw_timer.function = lcw_cb;
 282         lcw->lcw_timer.data = (unsigned long)lcw;
 283         lcw->lcw_timer.expires = jiffies + lcw->lcw_time;
 284         init_timer(&lcw->lcw_timer);
 285
 286         down(&lcw_refcount_sem);
 287         if (++lcw_refcount == 1)
 288                 lcw_dispatch_start();
 289         up(&lcw_refcount_sem);
 290
 291         /* Keep this working in case we enable them by default */
 292         if (lcw->lcw_state == LC_WATCHDOG_ENABLED) {
 293                 do_gettimeofday(&lcw->lcw_last_touched);
 294                 add_timer(&lcw->lcw_timer);
 295         }
 296
 297         RETURN(lcw);
 298 }
 299 EXPORT_SYMBOL(lc_watchdog_add);
 300
 301 static long
 302 timeval_sub(struct timeval *large, struct timeval *small)
 303 {
 304         return (large->tv_sec - small->tv_sec) * 1000000 +
 305                 (large->tv_usec - small->tv_usec);
 306 }
 307
 308 static void lcw_update_time(struct lc_watchdog *lcw, const char *message)
 309 {
 310         struct timeval newtime;
 311         unsigned long timediff;
 312
 313         do_gettimeofday(&newtime);
 314         if (lcw->lcw_state == LC_WATCHDOG_EXPIRED) {
 315                 timediff = timeval_sub(&newtime, &lcw->lcw_last_touched);
 316                 CWARN("Expired watchdog for pid %d %s after %lu.%.4lus\n",
 317                       lcw->lcw_pid,
 318                       message,
 319                       timediff / 1000000,
 320                       (timediff % 1000000) / 100);
 321         }
 322         lcw->lcw_last_touched = newtime;
 323 }
 324
 325 void lc_watchdog_touch(struct lc_watchdog *lcw)
 326 {
 327         unsigned long flags;
 328         ENTRY;
 329         LASSERT(lcw != NULL);
 330
 331         spin_lock_irqsave(&lcw_pending_timers_lock, flags);
 332         if (!list_empty(&lcw->lcw_list))
 333                 list_del_init(&lcw->lcw_list);
 334         spin_unlock_irqrestore(&lcw_pending_timers_lock, flags);
 335
 336         lcw_update_time(lcw, "touched");
 337         lcw->lcw_state = LC_WATCHDOG_ENABLED;
 338
 339         mod_timer(&lcw->lcw_timer, jiffies + lcw->lcw_time);
 340
 341         EXIT;
 342 }
 343 EXPORT_SYMBOL(lc_watchdog_touch);
 344
 345 void lc_watchdog_disable(struct lc_watchdog *lcw)
 346 {
 347         unsigned long flags;
 348         ENTRY;
 349         LASSERT(lcw != NULL);
 350
 351         spin_lock_irqsave(&lcw_pending_timers_lock, flags);
 352         if (!list_empty(&lcw->lcw_list))
 353                 list_del_init(&lcw->lcw_list);
 354         spin_unlock_irqrestore(&lcw_pending_timers_lock, flags);
 355
 356         lcw_update_time(lcw, "disabled");
 357         lcw->lcw_state = LC_WATCHDOG_DISABLED;
 358
 359         EXIT;
 360 }
 361 EXPORT_SYMBOL(lc_watchdog_disable);
 362
 363 void lc_watchdog_delete(struct lc_watchdog *lcw)
 364 {
 365         unsigned long flags;
 366         ENTRY;
 367         LASSERT(lcw != NULL);
 368
 369         del_timer(&lcw->lcw_timer);
 370
 371         lcw_update_time(lcw, "deleted");
 372
 373         spin_lock_irqsave(&lcw_pending_timers_lock, flags);
 374         if (!list_empty(&lcw->lcw_list))
 375                 list_del_init(&lcw->lcw_list);
 376         spin_unlock_irqrestore(&lcw_pending_timers_lock, flags);
 377
 378         down(&lcw_refcount_sem);
 379         if (--lcw_refcount == 0)
 380                 lcw_dispatch_stop();
 381         up(&lcw_refcount_sem);
 382
 383         PORTAL_FREE(lcw, sizeof(*lcw));
 384
 385         EXIT;
 386 }
 387 EXPORT_SYMBOL(lc_watchdog_delete);
 388
 389 /*
 390  * Provided watchdog handlers
 391  */
 392
 393 extern void portals_debug_dumplog_internal(void *arg);
 394
 395 void lc_watchdog_dumplog(struct lc_watchdog *lcw,
 396                          struct task_struct *tsk,
 397                          void               *data)
 398 {
 399         tsk = tsk ? tsk : current;
 400         portals_debug_dumplog_internal((void *)(long)tsk->pid);
 401 }
 402 EXPORT_SYMBOL(lc_watchdog_dumplog);