2 * Copyright (c) 2013, 2014 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include "ovs-thread.h"
29 #include "poll-loop.h"
30 #include "socket-util.h"
34 /* Omit the definitions in this file because they are somewhat difficult to
35 * write without prompting "sparse" complaints, without ugliness or
36 * cut-and-paste. Since "sparse" is just a checker, not a compiler, it
37 * doesn't matter that we don't define them. */
41 VLOG_DEFINE_THIS_MODULE(ovs_thread);
43 /* If there is a reason that we cannot fork anymore (unless the fork will be
44 * immediately followed by an exec), then this points to a string that
46 static const char *must_not_fork;
48 /* True if we created any threads beyond the main initial thread. */
49 static bool multithreaded;
51 #define LOCK_FUNCTION(TYPE, FUN) \
53 ovs_##TYPE##_##FUN##_at(const struct ovs_##TYPE *l_, \
55 OVS_NO_THREAD_SAFETY_ANALYSIS \
57 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
60 /* Verify that 'l' was initialized. */ \
61 if (OVS_UNLIKELY(!l->where)) { \
62 ovs_abort(0, "%s: %s() passed uninitialized ovs_"#TYPE, \
66 error = pthread_##TYPE##_##FUN(&l->lock); \
67 if (OVS_UNLIKELY(error)) { \
68 ovs_abort(error, "%s: pthread_%s_%s failed", where, #TYPE, #FUN); \
72 LOCK_FUNCTION(mutex, lock);
73 LOCK_FUNCTION(rwlock, rdlock);
74 LOCK_FUNCTION(rwlock, wrlock);
76 #define TRY_LOCK_FUNCTION(TYPE, FUN) \
78 ovs_##TYPE##_##FUN##_at(const struct ovs_##TYPE *l_, \
80 OVS_NO_THREAD_SAFETY_ANALYSIS \
82 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
85 /* Verify that 'l' was initialized. */ \
86 if (OVS_UNLIKELY(!l->where)) { \
87 ovs_abort(0, "%s: %s() passed uninitialized ovs_"#TYPE, \
91 error = pthread_##TYPE##_##FUN(&l->lock); \
92 if (OVS_UNLIKELY(error) && error != EBUSY) { \
93 ovs_abort(error, "%s: pthread_%s_%s failed", where, #TYPE, #FUN); \
100 TRY_LOCK_FUNCTION(mutex, trylock);
101 TRY_LOCK_FUNCTION(rwlock, tryrdlock);
102 TRY_LOCK_FUNCTION(rwlock, trywrlock);
104 #define UNLOCK_FUNCTION(TYPE, FUN, WHERE) \
106 ovs_##TYPE##_##FUN(const struct ovs_##TYPE *l_) \
107 OVS_NO_THREAD_SAFETY_ANALYSIS \
109 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
112 /* Verify that 'l' was initialized. */ \
113 ovs_assert(l->where); \
116 error = pthread_##TYPE##_##FUN(&l->lock); \
117 if (OVS_UNLIKELY(error)) { \
118 ovs_abort(error, "pthread_%s_%sfailed", #TYPE, #FUN); \
121 UNLOCK_FUNCTION(mutex, unlock, "<unlocked>");
122 UNLOCK_FUNCTION(mutex, destroy, NULL);
123 UNLOCK_FUNCTION(rwlock, unlock, "<unlocked>");
124 UNLOCK_FUNCTION(rwlock, destroy, NULL);
126 #define XPTHREAD_FUNC1(FUNCTION, PARAM1) \
128 x##FUNCTION(PARAM1 arg1) \
130 int error = FUNCTION(arg1); \
131 if (OVS_UNLIKELY(error)) { \
132 ovs_abort(error, "%s failed", #FUNCTION); \
135 #define XPTHREAD_FUNC2(FUNCTION, PARAM1, PARAM2) \
137 x##FUNCTION(PARAM1 arg1, PARAM2 arg2) \
139 int error = FUNCTION(arg1, arg2); \
140 if (OVS_UNLIKELY(error)) { \
141 ovs_abort(error, "%s failed", #FUNCTION); \
144 #define XPTHREAD_FUNC3(FUNCTION, PARAM1, PARAM2, PARAM3)\
146 x##FUNCTION(PARAM1 arg1, PARAM2 arg2, PARAM3 arg3) \
148 int error = FUNCTION(arg1, arg2, arg3); \
149 if (OVS_UNLIKELY(error)) { \
150 ovs_abort(error, "%s failed", #FUNCTION); \
154 XPTHREAD_FUNC1(pthread_mutex_lock, pthread_mutex_t *);
155 XPTHREAD_FUNC1(pthread_mutex_unlock, pthread_mutex_t *);
156 XPTHREAD_FUNC1(pthread_mutexattr_init, pthread_mutexattr_t *);
157 XPTHREAD_FUNC1(pthread_mutexattr_destroy, pthread_mutexattr_t *);
158 XPTHREAD_FUNC2(pthread_mutexattr_settype, pthread_mutexattr_t *, int);
159 XPTHREAD_FUNC2(pthread_mutexattr_gettype, pthread_mutexattr_t *, int *);
161 XPTHREAD_FUNC1(pthread_rwlockattr_init, pthread_rwlockattr_t *);
162 XPTHREAD_FUNC1(pthread_rwlockattr_destroy, pthread_rwlockattr_t *);
163 #ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
164 XPTHREAD_FUNC2(pthread_rwlockattr_setkind_np, pthread_rwlockattr_t *, int);
167 XPTHREAD_FUNC2(pthread_cond_init, pthread_cond_t *, pthread_condattr_t *);
168 XPTHREAD_FUNC1(pthread_cond_destroy, pthread_cond_t *);
169 XPTHREAD_FUNC1(pthread_cond_signal, pthread_cond_t *);
170 XPTHREAD_FUNC1(pthread_cond_broadcast, pthread_cond_t *);
172 XPTHREAD_FUNC3(pthread_barrier_init, pthread_barrier_t *,
173 pthread_barrierattr_t *, unsigned int);
174 XPTHREAD_FUNC1(pthread_barrier_destroy, pthread_barrier_t *);
176 XPTHREAD_FUNC2(pthread_join, pthread_t, void **);
178 typedef void destructor_func(void *);
179 XPTHREAD_FUNC2(pthread_key_create, pthread_key_t *, destructor_func *);
180 XPTHREAD_FUNC1(pthread_key_delete, pthread_key_t);
181 XPTHREAD_FUNC2(pthread_setspecific, pthread_key_t, const void *);
184 XPTHREAD_FUNC3(pthread_sigmask, int, const sigset_t *, sigset_t *);
188 ovs_mutex_init__(const struct ovs_mutex *l_, int type)
190 struct ovs_mutex *l = CONST_CAST(struct ovs_mutex *, l_);
191 pthread_mutexattr_t attr;
194 l->where = "<unlocked>";
195 xpthread_mutexattr_init(&attr);
196 xpthread_mutexattr_settype(&attr, type);
197 error = pthread_mutex_init(&l->lock, &attr);
198 if (OVS_UNLIKELY(error)) {
199 ovs_abort(error, "pthread_mutex_init failed");
201 xpthread_mutexattr_destroy(&attr);
204 /* Initializes 'mutex' as a normal (non-recursive) mutex. */
206 ovs_mutex_init(const struct ovs_mutex *mutex)
208 ovs_mutex_init__(mutex, PTHREAD_MUTEX_ERRORCHECK);
211 /* Initializes 'mutex' as a recursive mutex. */
213 ovs_mutex_init_recursive(const struct ovs_mutex *mutex)
215 ovs_mutex_init__(mutex, PTHREAD_MUTEX_RECURSIVE);
218 /* Initializes 'mutex' as a recursive mutex. */
220 ovs_mutex_init_adaptive(const struct ovs_mutex *mutex)
222 #ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
223 ovs_mutex_init__(mutex, PTHREAD_MUTEX_ADAPTIVE_NP);
225 ovs_mutex_init(mutex);
230 ovs_rwlock_init(const struct ovs_rwlock *l_)
232 struct ovs_rwlock *l = CONST_CAST(struct ovs_rwlock *, l_);
233 pthread_rwlockattr_t attr;
236 l->where = "<unlocked>";
238 xpthread_rwlockattr_init(&attr);
239 #ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
240 xpthread_rwlockattr_setkind_np(
241 &attr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
243 error = pthread_rwlock_init(&l->lock, NULL);
244 if (OVS_UNLIKELY(error)) {
245 ovs_abort(error, "pthread_rwlock_init failed");
247 xpthread_rwlockattr_destroy(&attr);
251 ovs_mutex_cond_wait(pthread_cond_t *cond, const struct ovs_mutex *mutex_)
253 struct ovs_mutex *mutex = CONST_CAST(struct ovs_mutex *, mutex_);
256 ovsrcu_quiesce_start();
257 error = pthread_cond_wait(cond, &mutex->lock);
258 ovsrcu_quiesce_end();
260 if (OVS_UNLIKELY(error)) {
261 ovs_abort(error, "pthread_cond_wait failed");
266 xpthread_barrier_wait(pthread_barrier_t *barrier)
270 ovsrcu_quiesce_start();
271 error = pthread_barrier_wait(barrier);
272 ovsrcu_quiesce_end();
274 if (error && OVS_UNLIKELY(error != PTHREAD_BARRIER_SERIAL_THREAD)) {
275 ovs_abort(error, "pthread_barrier_wait failed");
281 DEFINE_EXTERN_PER_THREAD_DATA(ovsthread_id, 0);
283 struct ovsthread_aux {
284 void *(*start)(void *);
290 ovsthread_wrapper(void *aux_)
292 static atomic_uint next_id = ATOMIC_VAR_INIT(1);
294 struct ovsthread_aux *auxp = aux_;
295 struct ovsthread_aux aux;
298 atomic_add(&next_id, 1, &id);
299 *ovsthread_id_get() = id;
304 /* The order of the following calls is important, because
305 * ovsrcu_quiesce_end() saves a copy of the thread name. */
306 set_subprogram_name("%s%u", aux.name, id);
307 ovsrcu_quiesce_end();
309 return aux.start(aux.arg);
312 /* Starts a thread that calls 'start(arg)'. Sets the thread's name to 'name'
313 * (suffixed by its ovsthread_id()). Returns the new thread's pthread_t. */
315 ovs_thread_create(const char *name, void *(*start)(void *), void *arg)
317 struct ovsthread_aux *aux;
321 forbid_forking("multiple threads exist");
322 multithreaded = true;
323 ovsrcu_quiesce_end();
325 aux = xmalloc(sizeof *aux);
328 ovs_strlcpy(aux->name, name, sizeof aux->name);
330 error = pthread_create(&thread, NULL, ovsthread_wrapper, aux);
332 ovs_abort(error, "pthread_create failed");
338 ovsthread_once_start__(struct ovsthread_once *once)
340 ovs_mutex_lock(&once->mutex);
341 if (!ovsthread_once_is_done__(once)) {
344 ovs_mutex_unlock(&once->mutex);
349 ovsthread_once_done(struct ovsthread_once *once)
351 atomic_store(&once->done, true);
352 ovs_mutex_unlock(&once->mutex);
356 single_threaded(void)
358 return !multithreaded;
361 /* Asserts that the process has not yet created any threads (beyond the initial
364 * ('where' is used in logging. Commonly one would use
365 * assert_single_threaded() to automatically provide the caller's source file
366 * and line number for 'where'.) */
368 assert_single_threaded_at(const char *where)
371 VLOG_FATAL("%s: attempted operation not allowed when multithreaded",
377 /* Forks the current process (checking that this is allowed). Aborts with
378 * VLOG_FATAL if fork() returns an error, and otherwise returns the value
379 * returned by fork().
381 * ('where' is used in logging. Commonly one would use xfork() to
382 * automatically provide the caller's source file and line number for
385 xfork_at(const char *where)
390 VLOG_FATAL("%s: attempted to fork but forking not allowed (%s)",
391 where, must_not_fork);
396 VLOG_FATAL("%s: fork failed (%s)", where, ovs_strerror(errno));
402 /* Notes that the process must not call fork() from now on, for the specified
403 * 'reason'. (The process may still fork() if it execs itself immediately
406 forbid_forking(const char *reason)
408 ovs_assert(reason != NULL);
409 must_not_fork = reason;
412 /* Returns true if the process is allowed to fork, false otherwise. */
416 return !must_not_fork;
419 /* ovsthread_stats. */
422 ovsthread_stats_init(struct ovsthread_stats *stats)
426 ovs_mutex_init(&stats->mutex);
427 for (i = 0; i < ARRAY_SIZE(stats->buckets); i++) {
428 stats->buckets[i] = NULL;
433 ovsthread_stats_destroy(struct ovsthread_stats *stats)
435 ovs_mutex_destroy(&stats->mutex);
439 ovsthread_stats_bucket_get(struct ovsthread_stats *stats,
440 void *(*new_bucket)(void))
442 unsigned int idx = ovsthread_id_self() & (ARRAY_SIZE(stats->buckets) - 1);
443 void *bucket = stats->buckets[idx];
445 ovs_mutex_lock(&stats->mutex);
446 bucket = stats->buckets[idx];
448 bucket = stats->buckets[idx] = new_bucket();
450 ovs_mutex_unlock(&stats->mutex);
456 ovs_thread_stats_next_bucket(const struct ovsthread_stats *stats, size_t i)
458 for (; i < ARRAY_SIZE(stats->buckets); i++) {
459 if (stats->buckets[i]) {
467 /* Parses /proc/cpuinfo for the total number of physical cores on this system
468 * across all CPU packages, not counting hyper-threads.
470 * Sets *n_cores to the total number of cores on this system, or 0 if the
471 * number cannot be determined. */
473 parse_cpuinfo(long int *n_cores)
475 static const char file_name[] = "/proc/cpuinfo";
477 uint64_t cpu = 0; /* Support up to 64 CPU packages on a single system. */
481 stream = fopen(file_name, "r");
483 VLOG_DBG("%s: open failed (%s)", file_name, ovs_strerror(errno));
487 while (fgets(line, sizeof line, stream)) {
490 /* Find the next CPU package. */
491 if (ovs_scan(line, "physical id%*[^:]: %u", &id)) {
493 VLOG_WARN("Counted over 64 CPU packages on this system. "
494 "Parsing %s for core count may be inaccurate.",
500 if (cpu & (1 << id)) {
501 /* We've already counted this package's cores. */
506 /* Find the number of cores for this package. */
507 while (fgets(line, sizeof line, stream)) {
510 if (ovs_scan(line, "cpu cores%*[^:]: %u", &count)) {
522 /* Returns the total number of cores on this system, or 0 if the number cannot
525 * Tries not to count hyper-threads, but may be inaccurate - particularly on
526 * platforms that do not provide /proc/cpuinfo, but also if /proc/cpuinfo is
527 * formatted different to the layout that parse_cpuinfo() expects. */
529 count_cpu_cores(void)
531 static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
532 static long int n_cores;
534 if (ovsthread_once_start(&once)) {
536 parse_cpuinfo(&n_cores);
538 n_cores = sysconf(_SC_NPROCESSORS_ONLN);
542 GetSystemInfo(&sysinfo);
543 n_cores = sysinfo.dwNumberOfProcessors;
545 ovsthread_once_done(&once);
548 return n_cores > 0 ? n_cores : 0;
555 #define MAX_KEYS (L1_SIZE * L2_SIZE)
557 /* A piece of thread-specific data. */
558 struct ovsthread_key {
559 struct list list_node; /* In 'inuse_keys' or 'free_keys'. */
560 void (*destructor)(void *); /* Called at thread exit. */
562 /* Indexes into the per-thread array in struct ovsthread_key_slots.
563 * This key's data is stored in p1[index / L2_SIZE][index % L2_SIZE]. */
567 /* Per-thread data structure. */
568 struct ovsthread_key_slots {
569 struct list list_node; /* In 'slots_list'. */
573 /* Contains "struct ovsthread_key_slots *". */
574 static pthread_key_t tsd_key;
576 /* Guards data structures below. */
577 static struct ovs_mutex key_mutex = OVS_MUTEX_INITIALIZER;
579 /* 'inuse_keys' holds "struct ovsthread_key"s that have been created and not
582 * 'free_keys' holds "struct ovsthread_key"s that have been deleted and are
583 * ready for reuse. (We keep them around only to be able to easily locate
586 * Together, 'inuse_keys' and 'free_keys' hold an ovsthread_key for every index
587 * from 0 to n_keys - 1, inclusive. */
588 static struct list inuse_keys OVS_GUARDED_BY(key_mutex)
589 = LIST_INITIALIZER(&inuse_keys);
590 static struct list free_keys OVS_GUARDED_BY(key_mutex)
591 = LIST_INITIALIZER(&free_keys);
592 static unsigned int n_keys OVS_GUARDED_BY(key_mutex);
594 /* All existing struct ovsthread_key_slots. */
595 static struct list slots_list OVS_GUARDED_BY(key_mutex)
596 = LIST_INITIALIZER(&slots_list);
599 clear_slot(struct ovsthread_key_slots *slots, unsigned int index)
601 void **p2 = slots->p1[index / L2_SIZE];
603 void **valuep = &p2[index % L2_SIZE];
604 void *value = *valuep;
613 ovsthread_key_destruct__(void *slots_)
615 struct ovsthread_key_slots *slots = slots_;
616 struct ovsthread_key *key;
620 ovs_mutex_lock(&key_mutex);
621 list_remove(&slots->list_node);
622 LIST_FOR_EACH (key, list_node, &inuse_keys) {
623 void *value = clear_slot(slots, key->index);
624 if (value && key->destructor) {
625 key->destructor(value);
629 ovs_mutex_unlock(&key_mutex);
631 for (i = 0; i < n / L2_SIZE; i++) {
637 /* Initializes '*keyp' as a thread-specific data key. The data items are
638 * initially null in all threads.
640 * If a thread exits with non-null data, then 'destructor', if nonnull, will be
641 * called passing the final data value as its argument. 'destructor' must not
642 * call any thread-specific data functions in this API.
644 * This function is similar to xpthread_key_create(). */
646 ovsthread_key_create(ovsthread_key_t *keyp, void (*destructor)(void *))
648 static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
649 struct ovsthread_key *key;
651 if (ovsthread_once_start(&once)) {
652 xpthread_key_create(&tsd_key, ovsthread_key_destruct__);
653 ovsthread_once_done(&once);
656 ovs_mutex_lock(&key_mutex);
657 if (list_is_empty(&free_keys)) {
658 key = xmalloc(sizeof *key);
659 key->index = n_keys++;
660 if (key->index >= MAX_KEYS) {
664 key = CONTAINER_OF(list_pop_back(&free_keys),
665 struct ovsthread_key, list_node);
667 list_push_back(&inuse_keys, &key->list_node);
668 key->destructor = destructor;
669 ovs_mutex_unlock(&key_mutex);
674 /* Frees 'key'. The destructor supplied to ovsthread_key_create(), if any, is
677 * This function is similar to xpthread_key_delete(). */
679 ovsthread_key_delete(ovsthread_key_t key)
681 struct ovsthread_key_slots *slots;
683 ovs_mutex_lock(&key_mutex);
685 /* Move 'key' from 'inuse_keys' to 'free_keys'. */
686 list_remove(&key->list_node);
687 list_push_back(&free_keys, &key->list_node);
689 /* Clear this slot in all threads. */
690 LIST_FOR_EACH (slots, list_node, &slots_list) {
691 clear_slot(slots, key->index);
694 ovs_mutex_unlock(&key_mutex);
698 ovsthread_key_lookup__(const struct ovsthread_key *key)
700 struct ovsthread_key_slots *slots;
703 slots = pthread_getspecific(tsd_key);
705 slots = xzalloc(sizeof *slots);
707 ovs_mutex_lock(&key_mutex);
708 pthread_setspecific(tsd_key, slots);
709 list_push_back(&slots_list, &slots->list_node);
710 ovs_mutex_unlock(&key_mutex);
713 p2 = slots->p1[key->index / L2_SIZE];
715 p2 = xzalloc(L2_SIZE * sizeof *p2);
716 slots->p1[key->index / L2_SIZE] = p2;
719 return &p2[key->index % L2_SIZE];
722 /* Sets the value of thread-specific data item 'key', in the current thread, to
725 * This function is similar to pthread_setspecific(). */
727 ovsthread_setspecific(ovsthread_key_t key, const void *value)
729 *ovsthread_key_lookup__(key) = CONST_CAST(void *, value);
732 /* Returns the value of thread-specific data item 'key' in the current thread.
734 * This function is similar to pthread_getspecific(). */
736 ovsthread_getspecific(ovsthread_key_t key)
738 return *ovsthread_key_lookup__(key);