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"
26 #include "poll-loop.h"
27 #include "socket-util.h"
31 /* Omit the definitions in this file because they are somewhat difficult to
32 * write without prompting "sparse" complaints, without ugliness or
33 * cut-and-paste. Since "sparse" is just a checker, not a compiler, it
34 * doesn't matter that we don't define them. */
38 VLOG_DEFINE_THIS_MODULE(ovs_thread);
40 /* If there is a reason that we cannot fork anymore (unless the fork will be
41 * immediately followed by an exec), then this points to a string that
43 static const char *must_not_fork;
45 /* True if we created any threads beyond the main initial thread. */
46 static bool multithreaded;
48 #define LOCK_FUNCTION(TYPE, FUN) \
50 ovs_##TYPE##_##FUN##_at(const struct ovs_##TYPE *l_, \
52 OVS_NO_THREAD_SAFETY_ANALYSIS \
54 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
57 /* Verify that 'l' was initialized. */ \
58 if (OVS_UNLIKELY(!l->where)) { \
59 ovs_abort(0, "%s: %s() passed uninitialized ovs_"#TYPE, \
63 error = pthread_##TYPE##_##FUN(&l->lock); \
64 if (OVS_UNLIKELY(error)) { \
65 ovs_abort(error, "%s: pthread_%s_%s failed", where, #TYPE, #FUN); \
69 LOCK_FUNCTION(mutex, lock);
70 LOCK_FUNCTION(rwlock, rdlock);
71 LOCK_FUNCTION(rwlock, wrlock);
73 #define TRY_LOCK_FUNCTION(TYPE, FUN) \
75 ovs_##TYPE##_##FUN##_at(const struct ovs_##TYPE *l_, \
77 OVS_NO_THREAD_SAFETY_ANALYSIS \
79 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
82 /* Verify that 'l' was initialized. */ \
83 if (OVS_UNLIKELY(!l->where)) { \
84 ovs_abort(0, "%s: %s() passed uninitialized ovs_"#TYPE, \
88 error = pthread_##TYPE##_##FUN(&l->lock); \
89 if (OVS_UNLIKELY(error) && error != EBUSY) { \
90 ovs_abort(error, "%s: pthread_%s_%s failed", where, #TYPE, #FUN); \
97 TRY_LOCK_FUNCTION(mutex, trylock);
98 TRY_LOCK_FUNCTION(rwlock, tryrdlock);
99 TRY_LOCK_FUNCTION(rwlock, trywrlock);
101 #define UNLOCK_FUNCTION(TYPE, FUN, WHERE) \
103 ovs_##TYPE##_##FUN(const struct ovs_##TYPE *l_) \
104 OVS_NO_THREAD_SAFETY_ANALYSIS \
106 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
109 /* Verify that 'l' was initialized. */ \
110 ovs_assert(l->where); \
113 error = pthread_##TYPE##_##FUN(&l->lock); \
114 if (OVS_UNLIKELY(error)) { \
115 ovs_abort(error, "pthread_%s_%sfailed", #TYPE, #FUN); \
118 UNLOCK_FUNCTION(mutex, unlock, "<unlocked>");
119 UNLOCK_FUNCTION(mutex, destroy, NULL);
120 UNLOCK_FUNCTION(rwlock, unlock, "<unlocked>");
121 UNLOCK_FUNCTION(rwlock, destroy, NULL);
123 #define XPTHREAD_FUNC1(FUNCTION, PARAM1) \
125 x##FUNCTION(PARAM1 arg1) \
127 int error = FUNCTION(arg1); \
128 if (OVS_UNLIKELY(error)) { \
129 ovs_abort(error, "%s failed", #FUNCTION); \
132 #define XPTHREAD_FUNC2(FUNCTION, PARAM1, PARAM2) \
134 x##FUNCTION(PARAM1 arg1, PARAM2 arg2) \
136 int error = FUNCTION(arg1, arg2); \
137 if (OVS_UNLIKELY(error)) { \
138 ovs_abort(error, "%s failed", #FUNCTION); \
141 #define XPTHREAD_FUNC3(FUNCTION, PARAM1, PARAM2, PARAM3)\
143 x##FUNCTION(PARAM1 arg1, PARAM2 arg2, PARAM3 arg3) \
145 int error = FUNCTION(arg1, arg2, arg3); \
146 if (OVS_UNLIKELY(error)) { \
147 ovs_abort(error, "%s failed", #FUNCTION); \
151 XPTHREAD_FUNC1(pthread_mutex_lock, pthread_mutex_t *);
152 XPTHREAD_FUNC1(pthread_mutex_unlock, pthread_mutex_t *);
153 XPTHREAD_FUNC1(pthread_mutexattr_init, pthread_mutexattr_t *);
154 XPTHREAD_FUNC1(pthread_mutexattr_destroy, pthread_mutexattr_t *);
155 XPTHREAD_FUNC2(pthread_mutexattr_settype, pthread_mutexattr_t *, int);
156 XPTHREAD_FUNC2(pthread_mutexattr_gettype, pthread_mutexattr_t *, int *);
158 XPTHREAD_FUNC1(pthread_rwlockattr_init, pthread_rwlockattr_t *);
159 XPTHREAD_FUNC1(pthread_rwlockattr_destroy, pthread_rwlockattr_t *);
160 #ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
161 XPTHREAD_FUNC2(pthread_rwlockattr_setkind_np, pthread_rwlockattr_t *, int);
164 XPTHREAD_FUNC2(pthread_cond_init, pthread_cond_t *, pthread_condattr_t *);
165 XPTHREAD_FUNC1(pthread_cond_destroy, pthread_cond_t *);
166 XPTHREAD_FUNC1(pthread_cond_signal, pthread_cond_t *);
167 XPTHREAD_FUNC1(pthread_cond_broadcast, pthread_cond_t *);
169 XPTHREAD_FUNC3(pthread_barrier_init, pthread_barrier_t *,
170 pthread_barrierattr_t *, unsigned int);
171 XPTHREAD_FUNC1(pthread_barrier_destroy, pthread_barrier_t *);
173 XPTHREAD_FUNC2(pthread_join, pthread_t, void **);
175 typedef void destructor_func(void *);
176 XPTHREAD_FUNC2(pthread_key_create, pthread_key_t *, destructor_func *);
177 XPTHREAD_FUNC1(pthread_key_delete, pthread_key_t);
178 XPTHREAD_FUNC2(pthread_setspecific, pthread_key_t, const void *);
181 ovs_mutex_init__(const struct ovs_mutex *l_, int type)
183 struct ovs_mutex *l = CONST_CAST(struct ovs_mutex *, l_);
184 pthread_mutexattr_t attr;
187 l->where = "<unlocked>";
188 xpthread_mutexattr_init(&attr);
189 xpthread_mutexattr_settype(&attr, type);
190 error = pthread_mutex_init(&l->lock, &attr);
191 if (OVS_UNLIKELY(error)) {
192 ovs_abort(error, "pthread_mutex_init failed");
194 xpthread_mutexattr_destroy(&attr);
197 /* Initializes 'mutex' as a normal (non-recursive) mutex. */
199 ovs_mutex_init(const struct ovs_mutex *mutex)
201 ovs_mutex_init__(mutex, PTHREAD_MUTEX_ERRORCHECK);
204 /* Initializes 'mutex' as a recursive mutex. */
206 ovs_mutex_init_recursive(const struct ovs_mutex *mutex)
208 ovs_mutex_init__(mutex, PTHREAD_MUTEX_RECURSIVE);
211 /* Initializes 'mutex' as a recursive mutex. */
213 ovs_mutex_init_adaptive(const struct ovs_mutex *mutex)
215 #ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
216 ovs_mutex_init__(mutex, PTHREAD_MUTEX_ADAPTIVE_NP);
218 ovs_mutex_init(mutex);
223 ovs_rwlock_init(const struct ovs_rwlock *l_)
225 struct ovs_rwlock *l = CONST_CAST(struct ovs_rwlock *, l_);
226 pthread_rwlockattr_t attr;
229 l->where = "<unlocked>";
231 xpthread_rwlockattr_init(&attr);
232 #ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
233 xpthread_rwlockattr_setkind_np(
234 &attr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
236 error = pthread_rwlock_init(&l->lock, NULL);
237 if (OVS_UNLIKELY(error)) {
238 ovs_abort(error, "pthread_rwlock_init failed");
240 xpthread_rwlockattr_destroy(&attr);
244 ovs_mutex_cond_wait(pthread_cond_t *cond, const struct ovs_mutex *mutex_)
246 struct ovs_mutex *mutex = CONST_CAST(struct ovs_mutex *, mutex_);
249 ovsrcu_quiesce_start();
250 error = pthread_cond_wait(cond, &mutex->lock);
251 ovsrcu_quiesce_end();
253 if (OVS_UNLIKELY(error)) {
254 ovs_abort(error, "pthread_cond_wait failed");
259 xpthread_barrier_wait(pthread_barrier_t *barrier)
263 ovsrcu_quiesce_start();
264 error = pthread_barrier_wait(barrier);
265 ovsrcu_quiesce_end();
267 if (error && OVS_UNLIKELY(error != PTHREAD_BARRIER_SERIAL_THREAD)) {
268 ovs_abort(error, "pthread_barrier_wait failed");
274 DEFINE_EXTERN_PER_THREAD_DATA(ovsthread_id, 0);
276 struct ovsthread_aux {
277 void *(*start)(void *);
283 ovsthread_wrapper(void *aux_)
285 static atomic_uint next_id = ATOMIC_VAR_INIT(1);
287 struct ovsthread_aux *auxp = aux_;
288 struct ovsthread_aux aux;
291 atomic_add(&next_id, 1, &id);
292 *ovsthread_id_get() = id;
297 /* The order of the following calls is important, because
298 * ovsrcu_quiesce_end() saves a copy of the thread name. */
299 set_subprogram_name("%s%u", aux.name, id);
300 ovsrcu_quiesce_end();
302 return aux.start(aux.arg);
305 /* Starts a thread that calls 'start(arg)'. Sets the thread's name to 'name'
306 * (suffixed by its ovsthread_id()). Returns the new thread's pthread_t. */
308 ovs_thread_create(const char *name, void *(*start)(void *), void *arg)
310 struct ovsthread_aux *aux;
314 forbid_forking("multiple threads exist");
315 multithreaded = true;
316 ovsrcu_quiesce_end();
318 aux = xmalloc(sizeof *aux);
321 ovs_strlcpy(aux->name, name, sizeof aux->name);
323 error = pthread_create(&thread, NULL, ovsthread_wrapper, aux);
325 ovs_abort(error, "pthread_create failed");
331 ovsthread_once_start__(struct ovsthread_once *once)
333 ovs_mutex_lock(&once->mutex);
334 if (!ovsthread_once_is_done__(once)) {
337 ovs_mutex_unlock(&once->mutex);
342 ovsthread_once_done(struct ovsthread_once *once)
344 atomic_store(&once->done, true);
345 ovs_mutex_unlock(&once->mutex);
349 single_threaded(void)
351 return !multithreaded;
354 /* Asserts that the process has not yet created any threads (beyond the initial
357 * ('where' is used in logging. Commonly one would use
358 * assert_single_threaded() to automatically provide the caller's source file
359 * and line number for 'where'.) */
361 assert_single_threaded_at(const char *where)
364 VLOG_FATAL("%s: attempted operation not allowed when multithreaded",
370 /* Forks the current process (checking that this is allowed). Aborts with
371 * VLOG_FATAL if fork() returns an error, and otherwise returns the value
372 * returned by fork().
374 * ('where' is used in logging. Commonly one would use xfork() to
375 * automatically provide the caller's source file and line number for
378 xfork_at(const char *where)
383 VLOG_FATAL("%s: attempted to fork but forking not allowed (%s)",
384 where, must_not_fork);
389 VLOG_FATAL("%s: fork failed (%s)", where, ovs_strerror(errno));
395 /* Notes that the process must not call fork() from now on, for the specified
396 * 'reason'. (The process may still fork() if it execs itself immediately
399 forbid_forking(const char *reason)
401 ovs_assert(reason != NULL);
402 must_not_fork = reason;
405 /* Returns true if the process is allowed to fork, false otherwise. */
409 return !must_not_fork;
412 /* ovsthread_stats. */
415 ovsthread_stats_init(struct ovsthread_stats *stats)
419 ovs_mutex_init(&stats->mutex);
420 for (i = 0; i < ARRAY_SIZE(stats->buckets); i++) {
421 stats->buckets[i] = NULL;
426 ovsthread_stats_destroy(struct ovsthread_stats *stats)
428 ovs_mutex_destroy(&stats->mutex);
432 ovsthread_stats_bucket_get(struct ovsthread_stats *stats,
433 void *(*new_bucket)(void))
435 unsigned int idx = ovsthread_id_self() & (ARRAY_SIZE(stats->buckets) - 1);
436 void *bucket = stats->buckets[idx];
438 ovs_mutex_lock(&stats->mutex);
439 bucket = stats->buckets[idx];
441 bucket = stats->buckets[idx] = new_bucket();
443 ovs_mutex_unlock(&stats->mutex);
449 ovs_thread_stats_next_bucket(const struct ovsthread_stats *stats, size_t i)
451 for (; i < ARRAY_SIZE(stats->buckets); i++) {
452 if (stats->buckets[i]) {
460 /* Parses /proc/cpuinfo for the total number of physical cores on this system
461 * across all CPU packages, not counting hyper-threads.
463 * Sets *n_cores to the total number of cores on this system, or 0 if the
464 * number cannot be determined. */
466 parse_cpuinfo(long int *n_cores)
468 static const char file_name[] = "/proc/cpuinfo";
470 uint64_t cpu = 0; /* Support up to 64 CPU packages on a single system. */
474 stream = fopen(file_name, "r");
476 VLOG_DBG("%s: open failed (%s)", file_name, ovs_strerror(errno));
480 while (fgets(line, sizeof line, stream)) {
483 /* Find the next CPU package. */
484 if (ovs_scan(line, "physical id%*[^:]: %u", &id)) {
486 VLOG_WARN("Counted over 64 CPU packages on this system. "
487 "Parsing %s for core count may be inaccurate.",
493 if (cpu & (1 << id)) {
494 /* We've already counted this package's cores. */
499 /* Find the number of cores for this package. */
500 while (fgets(line, sizeof line, stream)) {
503 if (ovs_scan(line, "cpu cores%*[^:]: %u", &count)) {
515 /* Returns the total number of cores on this system, or 0 if the number cannot
518 * Tries not to count hyper-threads, but may be inaccurate - particularly on
519 * platforms that do not provide /proc/cpuinfo, but also if /proc/cpuinfo is
520 * formatted different to the layout that parse_cpuinfo() expects. */
522 count_cpu_cores(void)
524 static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
525 static long int n_cores;
527 if (ovsthread_once_start(&once)) {
529 parse_cpuinfo(&n_cores);
531 n_cores = sysconf(_SC_NPROCESSORS_ONLN);
535 GetSystemInfo(&sysinfo);
536 n_cores = sysinfo.dwNumberOfProcessors;
538 ovsthread_once_done(&once);
541 return n_cores > 0 ? n_cores : 0;
548 #define MAX_KEYS (L1_SIZE * L2_SIZE)
550 /* A piece of thread-specific data. */
551 struct ovsthread_key {
552 struct list list_node; /* In 'inuse_keys' or 'free_keys'. */
553 void (*destructor)(void *); /* Called at thread exit. */
555 /* Indexes into the per-thread array in struct ovsthread_key_slots.
556 * This key's data is stored in p1[index / L2_SIZE][index % L2_SIZE]. */
560 /* Per-thread data structure. */
561 struct ovsthread_key_slots {
562 struct list list_node; /* In 'slots_list'. */
566 /* Contains "struct ovsthread_key_slots *". */
567 static pthread_key_t tsd_key;
569 /* Guards data structures below. */
570 static struct ovs_mutex key_mutex = OVS_MUTEX_INITIALIZER;
572 /* 'inuse_keys' holds "struct ovsthread_key"s that have been created and not
575 * 'free_keys' holds "struct ovsthread_key"s that have been deleted and are
576 * ready for reuse. (We keep them around only to be able to easily locate
579 * Together, 'inuse_keys' and 'free_keys' hold an ovsthread_key for every index
580 * from 0 to n_keys - 1, inclusive. */
581 static struct list inuse_keys OVS_GUARDED_BY(key_mutex)
582 = LIST_INITIALIZER(&inuse_keys);
583 static struct list free_keys OVS_GUARDED_BY(key_mutex)
584 = LIST_INITIALIZER(&free_keys);
585 static unsigned int n_keys OVS_GUARDED_BY(key_mutex);
587 /* All existing struct ovsthread_key_slots. */
588 static struct list slots_list OVS_GUARDED_BY(key_mutex)
589 = LIST_INITIALIZER(&slots_list);
592 clear_slot(struct ovsthread_key_slots *slots, unsigned int index)
594 void **p2 = slots->p1[index / L2_SIZE];
596 void **valuep = &p2[index % L2_SIZE];
597 void *value = *valuep;
606 ovsthread_key_destruct__(void *slots_)
608 struct ovsthread_key_slots *slots = slots_;
609 struct ovsthread_key *key;
613 ovs_mutex_lock(&key_mutex);
614 list_remove(&slots->list_node);
615 LIST_FOR_EACH (key, list_node, &inuse_keys) {
616 void *value = clear_slot(slots, key->index);
617 if (value && key->destructor) {
618 key->destructor(value);
622 ovs_mutex_unlock(&key_mutex);
624 for (i = 0; i < n / L2_SIZE; i++) {
630 /* Initializes '*keyp' as a thread-specific data key. The data items are
631 * initially null in all threads.
633 * If a thread exits with non-null data, then 'destructor', if nonnull, will be
634 * called passing the final data value as its argument. 'destructor' must not
635 * call any thread-specific data functions in this API.
637 * This function is similar to xpthread_key_create(). */
639 ovsthread_key_create(ovsthread_key_t *keyp, void (*destructor)(void *))
641 static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
642 struct ovsthread_key *key;
644 if (ovsthread_once_start(&once)) {
645 xpthread_key_create(&tsd_key, ovsthread_key_destruct__);
646 ovsthread_once_done(&once);
649 ovs_mutex_lock(&key_mutex);
650 if (list_is_empty(&free_keys)) {
651 key = xmalloc(sizeof *key);
652 key->index = n_keys++;
653 if (key->index >= MAX_KEYS) {
657 key = CONTAINER_OF(list_pop_back(&free_keys),
658 struct ovsthread_key, list_node);
660 list_push_back(&inuse_keys, &key->list_node);
661 key->destructor = destructor;
662 ovs_mutex_unlock(&key_mutex);
667 /* Frees 'key'. The destructor supplied to ovsthread_key_create(), if any, is
670 * This function is similar to xpthread_key_delete(). */
672 ovsthread_key_delete(ovsthread_key_t key)
674 struct ovsthread_key_slots *slots;
676 ovs_mutex_lock(&key_mutex);
678 /* Move 'key' from 'inuse_keys' to 'free_keys'. */
679 list_remove(&key->list_node);
680 list_push_back(&free_keys, &key->list_node);
682 /* Clear this slot in all threads. */
683 LIST_FOR_EACH (slots, list_node, &slots_list) {
684 clear_slot(slots, key->index);
687 ovs_mutex_unlock(&key_mutex);
691 ovsthread_key_lookup__(const struct ovsthread_key *key)
693 struct ovsthread_key_slots *slots;
696 slots = pthread_getspecific(tsd_key);
698 slots = xzalloc(sizeof *slots);
700 ovs_mutex_lock(&key_mutex);
701 pthread_setspecific(tsd_key, slots);
702 list_push_back(&slots_list, &slots->list_node);
703 ovs_mutex_unlock(&key_mutex);
706 p2 = slots->p1[key->index / L2_SIZE];
708 p2 = xzalloc(L2_SIZE * sizeof *p2);
709 slots->p1[key->index / L2_SIZE] = p2;
712 return &p2[key->index % L2_SIZE];
715 /* Sets the value of thread-specific data item 'key', in the current thread, to
718 * This function is similar to pthread_setspecific(). */
720 ovsthread_setspecific(ovsthread_key_t key, const void *value)
722 *ovsthread_key_lookup__(key) = CONST_CAST(void *, value);
725 /* Returns the value of thread-specific data item 'key' in the current thread.
727 * This function is similar to pthread_getspecific(). */
729 ovsthread_getspecific(ovsthread_key_t key)
731 return *ovsthread_key_lookup__(key);