1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
2 * vim:expandtab:shiftwidth=8:tabstop=8:
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15 * General Public License version 2 for more details (a copy is included
16 * in the LICENSE file that accompanied this code).
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29 * Copyright 2008 Sun Microsystems, Inc. All rights reserved
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33 * This file is part of Lustre, http://www.lustre.org/
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36 * libcfs/libcfs/watchdog.c
38 * Author: Jacob Berkman <jacob@clusterfs.com>
41 #define DEBUG_SUBSYSTEM S_LNET
43 #include <libcfs/libcfs.h>
44 #include "tracefile.h"
47 cfs_timer_t lcw_timer; /* kernel timer */
48 struct list_head lcw_list;
49 struct timeval lcw_last_touched;
52 void (*lcw_callback)(pid_t, void *);
56 cfs_duration_t lcw_time; /* time until watchdog fires, jiffies */
67 * The dispatcher will complete lcw_start_completion when it starts,
68 * and lcw_stop_completion when it exits.
69 * Wake lcw_event_waitq to signal timer callback dispatches.
71 static struct completion lcw_start_completion;
72 static struct completion lcw_stop_completion;
73 static cfs_waitq_t lcw_event_waitq;
76 * Set this and wake lcw_event_waitq to stop the dispatcher.
81 static unsigned long lcw_flags = 0;
84 * Number of outstanding watchdogs.
85 * When it hits 1, we start the dispatcher.
86 * When it hits 0, we stop the distpatcher.
88 static __u32 lcw_refcount = 0;
89 static DECLARE_MUTEX(lcw_refcount_sem);
92 * List of timers that have fired that need their callbacks run by the
95 static spinlock_t lcw_pending_timers_lock = SPIN_LOCK_UNLOCKED; /* BH lock! */
96 static struct list_head lcw_pending_timers = \
97 CFS_LIST_HEAD_INIT(lcw_pending_timers);
99 /* Last time a watchdog expired */
100 static cfs_time_t lcw_last_watchdog_time;
101 static int lcw_recent_watchdog_count;
102 static spinlock_t lcw_last_watchdog_lock = SPIN_LOCK_UNLOCKED;
105 lcw_dump(struct lc_watchdog *lcw)
108 #if defined(HAVE_TASKLIST_LOCK)
109 read_lock(&tasklist_lock);
110 #elif defined(HAVE_TASK_RCU)
113 CERROR("unable to dump stack because of missing export\n");
118 tsk = find_task_by_pid(lcw->lcw_pid);
121 CWARN("Process " LPPID " was not found in the task list; "
122 "watchdog callback may be incomplete\n", lcw->lcw_pid);
123 } else if (tsk != lcw->lcw_task) {
124 CWARN("The current process " LPPID " did not set the watchdog; "
125 "watchdog callback may be incomplete\n", lcw->lcw_pid);
127 libcfs_debug_dumpstack(tsk);
130 #if defined(HAVE_TASKLIST_LOCK)
131 read_unlock(&tasklist_lock);
132 #elif defined(HAVE_TASK_RCU)
138 static void lcw_cb(ulong_ptr_t data)
140 struct lc_watchdog *lcw = (struct lc_watchdog *)data;
141 cfs_time_t current_time;
142 cfs_duration_t delta_time;
146 if (lcw->lcw_state != LC_WATCHDOG_ENABLED) {
151 lcw->lcw_state = LC_WATCHDOG_EXPIRED;
152 current_time = cfs_time_current();
154 /* Check to see if we should throttle the watchdog timer to avoid
155 * too many dumps going to the console thus triggering an NMI.
156 * Normally we would not hold the spin lock over the CWARN but in
157 * this case we hold it to ensure non ratelimited lcw_dumps are not
158 * interleaved on the console making them hard to read. */
159 spin_lock_bh(&lcw_last_watchdog_lock);
160 delta_time = cfs_duration_sec(current_time - lcw_last_watchdog_time);
162 if (delta_time < libcfs_watchdog_ratelimit && lcw_recent_watchdog_count > 3) {
163 CWARN("Refusing to fire watchdog for pid %d: it was inactive "
164 "for %ldms. Rate limiting 1 per %d seconds.\n",
165 (int)lcw->lcw_pid,cfs_duration_sec(lcw->lcw_time) * 1000,
166 libcfs_watchdog_ratelimit);
168 if (delta_time < libcfs_watchdog_ratelimit) {
169 lcw_recent_watchdog_count++;
171 memcpy(&lcw_last_watchdog_time, ¤t_time,
172 sizeof(current_time));
173 lcw_recent_watchdog_count = 0;
176 /* This warning should appear on the console, but may not get
177 * into the logs since we're running in a softirq handler */
178 CWARN("Watchdog triggered for pid %d: it was inactive for %lds\n",
179 (int)lcw->lcw_pid, cfs_duration_sec(lcw->lcw_time));
183 spin_unlock_bh(&lcw_last_watchdog_lock);
184 spin_lock_bh(&lcw_pending_timers_lock);
186 if (list_empty(&lcw->lcw_list)) {
187 list_add(&lcw->lcw_list, &lcw_pending_timers);
188 cfs_waitq_signal(&lcw_event_waitq);
191 spin_unlock_bh(&lcw_pending_timers_lock);
196 static int is_watchdog_fired(void)
200 if (test_bit(LCW_FLAG_STOP, &lcw_flags))
203 spin_lock_bh(&lcw_pending_timers_lock);
204 rc = !list_empty(&lcw_pending_timers);
205 spin_unlock_bh(&lcw_pending_timers_lock);
209 static int lcw_dispatch_main(void *data)
213 struct lc_watchdog *lcw;
217 cfs_daemonize("lc_watchdogd");
219 SIGNAL_MASK_LOCK(current, flags);
220 sigfillset(¤t->blocked);
222 SIGNAL_MASK_UNLOCK(current, flags);
224 complete(&lcw_start_completion);
227 cfs_wait_event_interruptible(lcw_event_waitq, is_watchdog_fired(), rc);
228 CDEBUG(D_INFO, "Watchdog got woken up...\n");
229 if (test_bit(LCW_FLAG_STOP, &lcw_flags)) {
230 CDEBUG(D_INFO, "LCW_FLAG_STOP was set, shutting down...\n");
232 spin_lock_bh(&lcw_pending_timers_lock);
233 rc = !list_empty(&lcw_pending_timers);
234 spin_unlock_bh(&lcw_pending_timers_lock);
236 CERROR("pending timers list was not empty at "
237 "time of watchdog dispatch shutdown\n");
242 spin_lock_bh(&lcw_pending_timers_lock);
243 while (!list_empty(&lcw_pending_timers)) {
245 lcw = list_entry(lcw_pending_timers.next,
248 list_del_init(&lcw->lcw_list);
249 spin_unlock_bh(&lcw_pending_timers_lock);
251 CDEBUG(D_INFO, "found lcw for pid " LPPID ": inactive for "
252 "%lds\n", lcw->lcw_pid, cfs_duration_sec(lcw->lcw_time));
254 if (lcw->lcw_state != LC_WATCHDOG_DISABLED)
255 lcw->lcw_callback(lcw->lcw_pid, lcw->lcw_data);
257 spin_lock_bh(&lcw_pending_timers_lock);
259 spin_unlock_bh(&lcw_pending_timers_lock);
262 complete(&lcw_stop_completion);
267 static void lcw_dispatch_start(void)
272 LASSERT(lcw_refcount == 1);
274 init_completion(&lcw_stop_completion);
275 init_completion(&lcw_start_completion);
276 cfs_waitq_init(&lcw_event_waitq);
278 CDEBUG(D_INFO, "starting dispatch thread\n");
279 rc = kernel_thread(lcw_dispatch_main, NULL, 0);
281 CERROR("error spawning watchdog dispatch thread: %d\n", rc);
285 wait_for_completion(&lcw_start_completion);
286 CDEBUG(D_INFO, "watchdog dispatcher initialization complete.\n");
291 static void lcw_dispatch_stop(void)
294 LASSERT(lcw_refcount == 0);
296 CDEBUG(D_INFO, "trying to stop watchdog dispatcher.\n");
298 set_bit(LCW_FLAG_STOP, &lcw_flags);
299 cfs_waitq_signal(&lcw_event_waitq);
301 wait_for_completion(&lcw_stop_completion);
303 CDEBUG(D_INFO, "watchdog dispatcher has shut down.\n");
308 struct lc_watchdog *lc_watchdog_add(int timeout_ms,
309 void (*callback)(pid_t, void *),
312 struct lc_watchdog *lcw = NULL;
315 LIBCFS_ALLOC(lcw, sizeof(*lcw));
317 CDEBUG(D_INFO, "Could not allocate new lc_watchdog\n");
318 RETURN(ERR_PTR(-ENOMEM));
321 lcw->lcw_task = cfs_current();
322 lcw->lcw_pid = cfs_curproc_pid();
323 lcw->lcw_time = cfs_time_seconds(timeout_ms) / 1000;
324 lcw->lcw_callback = (callback != NULL) ? callback : lc_watchdog_dumplog;
325 lcw->lcw_data = data;
326 lcw->lcw_state = LC_WATCHDOG_DISABLED;
328 CFS_INIT_LIST_HEAD(&lcw->lcw_list);
329 cfs_timer_init(&lcw->lcw_timer, lcw_cb, lcw);
331 down(&lcw_refcount_sem);
332 if (++lcw_refcount == 1)
333 lcw_dispatch_start();
334 up(&lcw_refcount_sem);
336 /* Keep this working in case we enable them by default */
337 if (lcw->lcw_state == LC_WATCHDOG_ENABLED) {
338 do_gettimeofday(&lcw->lcw_last_touched);
339 cfs_timer_arm(&lcw->lcw_timer, lcw->lcw_time +
345 EXPORT_SYMBOL(lc_watchdog_add);
347 static void lcw_update_time(struct lc_watchdog *lcw, const char *message)
349 struct timeval newtime;
350 struct timeval timediff;
352 do_gettimeofday(&newtime);
353 if (lcw->lcw_state == LC_WATCHDOG_EXPIRED) {
354 cfs_timeval_sub(&newtime, &lcw->lcw_last_touched, &timediff);
355 CWARN("Expired watchdog for pid " LPPID " %s after %lu.%.4lus\n",
359 timediff.tv_usec / 100);
361 lcw->lcw_last_touched = newtime;
364 void lc_watchdog_touch_ms(struct lc_watchdog *lcw, int timeout_ms)
367 LASSERT(lcw != NULL);
369 spin_lock_bh(&lcw_pending_timers_lock);
370 list_del_init(&lcw->lcw_list);
371 spin_unlock_bh(&lcw_pending_timers_lock);
373 lcw_update_time(lcw, "touched");
374 lcw->lcw_state = LC_WATCHDOG_ENABLED;
376 cfs_timer_arm(&lcw->lcw_timer, cfs_time_current() +
377 cfs_time_seconds(timeout_ms) / 1000);
381 EXPORT_SYMBOL(lc_watchdog_touch_ms);
383 /* deprecated - use above instead */
384 void lc_watchdog_touch(struct lc_watchdog *lcw)
386 lc_watchdog_touch_ms(lcw, (int)cfs_duration_sec(lcw->lcw_time) * 1000);
388 EXPORT_SYMBOL(lc_watchdog_touch);
390 void lc_watchdog_disable(struct lc_watchdog *lcw)
393 LASSERT(lcw != NULL);
395 spin_lock_bh(&lcw_pending_timers_lock);
396 if (!list_empty(&lcw->lcw_list))
397 list_del_init(&lcw->lcw_list);
398 spin_unlock_bh(&lcw_pending_timers_lock);
400 lcw_update_time(lcw, "disabled");
401 lcw->lcw_state = LC_WATCHDOG_DISABLED;
405 EXPORT_SYMBOL(lc_watchdog_disable);
407 void lc_watchdog_delete(struct lc_watchdog *lcw)
410 LASSERT(lcw != NULL);
412 cfs_timer_disarm(&lcw->lcw_timer);
414 lcw_update_time(lcw, "deleted");
416 spin_lock_bh(&lcw_pending_timers_lock);
417 if (!list_empty(&lcw->lcw_list))
418 list_del_init(&lcw->lcw_list);
419 spin_unlock_bh(&lcw_pending_timers_lock);
421 down(&lcw_refcount_sem);
422 if (--lcw_refcount == 0)
424 up(&lcw_refcount_sem);
426 LIBCFS_FREE(lcw, sizeof(*lcw));
430 EXPORT_SYMBOL(lc_watchdog_delete);
433 * Provided watchdog handlers
436 void lc_watchdog_dumplog(pid_t pid, void *data)
438 libcfs_debug_dumplog_internal((void *)((long_ptr_t)pid));
440 EXPORT_SYMBOL(lc_watchdog_dumplog);
442 #else /* !defined(WITH_WATCHDOG) */
444 struct lc_watchdog *lc_watchdog_add(int timeout_ms,
445 void (*callback)(pid_t pid, void *),
448 static struct lc_watchdog watchdog;
451 EXPORT_SYMBOL(lc_watchdog_add);
453 void lc_watchdog_touch_ms(struct lc_watchdog *lcw, int timeout_ms)
456 EXPORT_SYMBOL(lc_watchdog_touch_ms);
458 void lc_watchdog_touch(struct lc_watchdog *lcw)
461 EXPORT_SYMBOL(lc_watchdog_touch);
463 void lc_watchdog_disable(struct lc_watchdog *lcw)
466 EXPORT_SYMBOL(lc_watchdog_disable);
468 void lc_watchdog_delete(struct lc_watchdog *lcw)
471 EXPORT_SYMBOL(lc_watchdog_delete);