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"
25 #include "poll-loop.h"
26 #include "socket-util.h"
30 /* Omit the definitions in this file because they are somewhat difficult to
31 * write without prompting "sparse" complaints, without ugliness or
32 * cut-and-paste. Since "sparse" is just a checker, not a compiler, it
33 * doesn't matter that we don't define them. */
37 VLOG_DEFINE_THIS_MODULE(ovs_thread);
39 /* If there is a reason that we cannot fork anymore (unless the fork will be
40 * immediately followed by an exec), then this points to a string that
42 static const char *must_not_fork;
44 /* True if we created any threads beyond the main initial thread. */
45 static bool multithreaded;
47 #define LOCK_FUNCTION(TYPE, FUN) \
49 ovs_##TYPE##_##FUN##_at(const struct ovs_##TYPE *l_, \
51 OVS_NO_THREAD_SAFETY_ANALYSIS \
53 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
54 int error = pthread_##TYPE##_##FUN(&l->lock); \
55 if (OVS_UNLIKELY(error)) { \
56 ovs_abort(error, "pthread_%s_%s failed", #TYPE, #FUN); \
60 LOCK_FUNCTION(mutex, lock);
61 LOCK_FUNCTION(rwlock, rdlock);
62 LOCK_FUNCTION(rwlock, wrlock);
64 #define TRY_LOCK_FUNCTION(TYPE, FUN) \
66 ovs_##TYPE##_##FUN##_at(const struct ovs_##TYPE *l_, \
68 OVS_NO_THREAD_SAFETY_ANALYSIS \
70 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
71 int error = pthread_##TYPE##_##FUN(&l->lock); \
72 if (OVS_UNLIKELY(error) && error != EBUSY) { \
73 ovs_abort(error, "pthread_%s_%s failed", #TYPE, #FUN); \
80 TRY_LOCK_FUNCTION(mutex, trylock);
81 TRY_LOCK_FUNCTION(rwlock, tryrdlock);
82 TRY_LOCK_FUNCTION(rwlock, trywrlock);
84 #define UNLOCK_FUNCTION(TYPE, FUN) \
86 ovs_##TYPE##_##FUN(const struct ovs_##TYPE *l_) \
87 OVS_NO_THREAD_SAFETY_ANALYSIS \
89 struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
92 error = pthread_##TYPE##_##FUN(&l->lock); \
93 if (OVS_UNLIKELY(error)) { \
94 ovs_abort(error, "pthread_%s_%sfailed", #TYPE, #FUN); \
97 UNLOCK_FUNCTION(mutex, unlock);
98 UNLOCK_FUNCTION(mutex, destroy);
99 UNLOCK_FUNCTION(rwlock, unlock);
100 UNLOCK_FUNCTION(rwlock, destroy);
102 #define XPTHREAD_FUNC1(FUNCTION, PARAM1) \
104 x##FUNCTION(PARAM1 arg1) \
106 int error = FUNCTION(arg1); \
107 if (OVS_UNLIKELY(error)) { \
108 ovs_abort(error, "%s failed", #FUNCTION); \
111 #define XPTHREAD_FUNC2(FUNCTION, PARAM1, PARAM2) \
113 x##FUNCTION(PARAM1 arg1, PARAM2 arg2) \
115 int error = FUNCTION(arg1, arg2); \
116 if (OVS_UNLIKELY(error)) { \
117 ovs_abort(error, "%s failed", #FUNCTION); \
120 #define XPTHREAD_FUNC3(FUNCTION, PARAM1, PARAM2, PARAM3)\
122 x##FUNCTION(PARAM1 arg1, PARAM2 arg2, PARAM3 arg3) \
124 int error = FUNCTION(arg1, arg2, arg3); \
125 if (OVS_UNLIKELY(error)) { \
126 ovs_abort(error, "%s failed", #FUNCTION); \
130 XPTHREAD_FUNC1(pthread_mutex_lock, pthread_mutex_t *);
131 XPTHREAD_FUNC1(pthread_mutex_unlock, pthread_mutex_t *);
132 XPTHREAD_FUNC1(pthread_mutexattr_init, pthread_mutexattr_t *);
133 XPTHREAD_FUNC1(pthread_mutexattr_destroy, pthread_mutexattr_t *);
134 XPTHREAD_FUNC2(pthread_mutexattr_settype, pthread_mutexattr_t *, int);
135 XPTHREAD_FUNC2(pthread_mutexattr_gettype, pthread_mutexattr_t *, int *);
137 XPTHREAD_FUNC1(pthread_rwlockattr_init, pthread_rwlockattr_t *);
138 XPTHREAD_FUNC1(pthread_rwlockattr_destroy, pthread_rwlockattr_t *);
139 #ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
140 XPTHREAD_FUNC2(pthread_rwlockattr_setkind_np, pthread_rwlockattr_t *, int);
143 XPTHREAD_FUNC2(pthread_cond_init, pthread_cond_t *, pthread_condattr_t *);
144 XPTHREAD_FUNC1(pthread_cond_destroy, pthread_cond_t *);
145 XPTHREAD_FUNC1(pthread_cond_signal, pthread_cond_t *);
146 XPTHREAD_FUNC1(pthread_cond_broadcast, pthread_cond_t *);
148 XPTHREAD_FUNC3(pthread_barrier_init, pthread_barrier_t *,
149 pthread_barrierattr_t *, unsigned int);
150 XPTHREAD_FUNC1(pthread_barrier_destroy, pthread_barrier_t *);
152 XPTHREAD_FUNC2(pthread_join, pthread_t, void **);
154 typedef void destructor_func(void *);
155 XPTHREAD_FUNC2(pthread_key_create, pthread_key_t *, destructor_func *);
156 XPTHREAD_FUNC1(pthread_key_delete, pthread_key_t);
157 XPTHREAD_FUNC2(pthread_setspecific, pthread_key_t, const void *);
160 ovs_mutex_init__(const struct ovs_mutex *l_, int type)
162 struct ovs_mutex *l = CONST_CAST(struct ovs_mutex *, l_);
163 pthread_mutexattr_t attr;
167 xpthread_mutexattr_init(&attr);
168 xpthread_mutexattr_settype(&attr, type);
169 error = pthread_mutex_init(&l->lock, &attr);
170 if (OVS_UNLIKELY(error)) {
171 ovs_abort(error, "pthread_mutex_init failed");
173 xpthread_mutexattr_destroy(&attr);
176 /* Initializes 'mutex' as a normal (non-recursive) mutex. */
178 ovs_mutex_init(const struct ovs_mutex *mutex)
180 ovs_mutex_init__(mutex, PTHREAD_MUTEX_ERRORCHECK);
183 /* Initializes 'mutex' as a recursive mutex. */
185 ovs_mutex_init_recursive(const struct ovs_mutex *mutex)
187 ovs_mutex_init__(mutex, PTHREAD_MUTEX_RECURSIVE);
190 /* Initializes 'mutex' as a recursive mutex. */
192 ovs_mutex_init_adaptive(const struct ovs_mutex *mutex)
194 #ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
195 ovs_mutex_init__(mutex, PTHREAD_MUTEX_ADAPTIVE_NP);
197 ovs_mutex_init(mutex);
202 ovs_rwlock_init(const struct ovs_rwlock *l_)
204 struct ovs_rwlock *l = CONST_CAST(struct ovs_rwlock *, l_);
205 pthread_rwlockattr_t attr;
210 xpthread_rwlockattr_init(&attr);
211 #ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
212 xpthread_rwlockattr_setkind_np(
213 &attr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
215 error = pthread_rwlock_init(&l->lock, NULL);
216 if (OVS_UNLIKELY(error)) {
217 ovs_abort(error, "pthread_rwlock_init failed");
219 xpthread_rwlockattr_destroy(&attr);
223 ovs_mutex_cond_wait(pthread_cond_t *cond, const struct ovs_mutex *mutex_)
225 struct ovs_mutex *mutex = CONST_CAST(struct ovs_mutex *, mutex_);
226 int error = pthread_cond_wait(cond, &mutex->lock);
227 if (OVS_UNLIKELY(error)) {
228 ovs_abort(error, "pthread_cond_wait failed");
233 xpthread_barrier_wait(pthread_barrier_t *barrier)
237 error = pthread_barrier_wait(barrier);
238 if (error && OVS_UNLIKELY(error != PTHREAD_BARRIER_SERIAL_THREAD)) {
239 ovs_abort(error, "pthread_barrier_wait failed");
245 DEFINE_EXTERN_PER_THREAD_DATA(ovsthread_id, 0);
247 struct ovsthread_aux {
248 void *(*start)(void *);
253 ovsthread_wrapper(void *aux_)
255 static atomic_uint next_id = ATOMIC_VAR_INIT(1);
257 struct ovsthread_aux *auxp = aux_;
258 struct ovsthread_aux aux;
261 atomic_add(&next_id, 1, &id);
262 *ovsthread_id_get() = id;
267 return aux.start(aux.arg);
271 xpthread_create(pthread_t *threadp, pthread_attr_t *attr,
272 void *(*start)(void *), void *arg)
274 struct ovsthread_aux *aux;
278 forbid_forking("multiple threads exist");
279 multithreaded = true;
281 aux = xmalloc(sizeof *aux);
285 error = pthread_create(threadp ? threadp : &thread, attr,
286 ovsthread_wrapper, aux);
288 ovs_abort(error, "pthread_create failed");
293 ovsthread_once_start__(struct ovsthread_once *once)
295 ovs_mutex_lock(&once->mutex);
296 if (!ovsthread_once_is_done__(once)) {
299 ovs_mutex_unlock(&once->mutex);
304 ovsthread_once_done(struct ovsthread_once *once)
306 atomic_store(&once->done, true);
307 ovs_mutex_unlock(&once->mutex);
310 /* Asserts that the process has not yet created any threads (beyond the initial
313 * ('where' is used in logging. Commonly one would use
314 * assert_single_threaded() to automatically provide the caller's source file
315 * and line number for 'where'.) */
317 assert_single_threaded_at(const char *where)
320 VLOG_FATAL("%s: attempted operation not allowed when multithreaded",
325 /* Forks the current process (checking that this is allowed). Aborts with
326 * VLOG_FATAL if fork() returns an error, and otherwise returns the value
327 * returned by fork().
329 * ('where' is used in logging. Commonly one would use xfork() to
330 * automatically provide the caller's source file and line number for
333 xfork_at(const char *where)
338 VLOG_FATAL("%s: attempted to fork but forking not allowed (%s)",
339 where, must_not_fork);
344 VLOG_FATAL("%s: fork failed (%s)", where, ovs_strerror(errno));
349 /* Notes that the process must not call fork() from now on, for the specified
350 * 'reason'. (The process may still fork() if it execs itself immediately
353 forbid_forking(const char *reason)
355 ovs_assert(reason != NULL);
356 must_not_fork = reason;
359 /* Returns true if the process is allowed to fork, false otherwise. */
363 return !must_not_fork;
366 /* ovsthread_counter.
368 * We implement the counter as an array of N_COUNTERS individual counters, each
369 * with its own lock. Each thread uses one of the counters chosen based on a
370 * hash of the thread's ID, the idea being that, statistically, different
371 * threads will tend to use different counters and therefore avoid
372 * interfering with each other.
374 * Undoubtedly, better implementations are possible. */
376 /* Basic counter structure. */
377 struct ovsthread_counter__ {
378 struct ovs_mutex mutex;
379 unsigned long long int value;
382 /* Pad the basic counter structure to 64 bytes to avoid cache line
384 struct ovsthread_counter {
385 struct ovsthread_counter__ c;
386 char pad[ROUND_UP(sizeof(struct ovsthread_counter__), 64)
387 - sizeof(struct ovsthread_counter__)];
390 #define N_COUNTERS 16
392 struct ovsthread_counter *
393 ovsthread_counter_create(void)
395 struct ovsthread_counter *c;
398 c = xmalloc(N_COUNTERS * sizeof *c);
399 for (i = 0; i < N_COUNTERS; i++) {
400 ovs_mutex_init(&c[i].c.mutex);
407 ovsthread_counter_destroy(struct ovsthread_counter *c)
412 for (i = 0; i < N_COUNTERS; i++) {
413 ovs_mutex_destroy(&c[i].c.mutex);
420 ovsthread_counter_inc(struct ovsthread_counter *c, unsigned long long int n)
422 c = &c[hash_int(ovsthread_id_self(), 0) % N_COUNTERS];
424 ovs_mutex_lock(&c->c.mutex);
426 ovs_mutex_unlock(&c->c.mutex);
429 unsigned long long int
430 ovsthread_counter_read(const struct ovsthread_counter *c)
432 unsigned long long int sum;
436 for (i = 0; i < N_COUNTERS; i++) {
437 ovs_mutex_lock(&c[i].c.mutex);
439 ovs_mutex_unlock(&c[i].c.mutex);
444 /* Parses /proc/cpuinfo for the total number of physical cores on this system
445 * across all CPU packages, not counting hyper-threads.
447 * Sets *n_cores to the total number of cores on this system, or 0 if the
448 * number cannot be determined. */
450 parse_cpuinfo(long int *n_cores)
452 static const char file_name[] = "/proc/cpuinfo";
454 uint64_t cpu = 0; /* Support up to 64 CPU packages on a single system. */
458 stream = fopen(file_name, "r");
460 VLOG_DBG("%s: open failed (%s)", file_name, ovs_strerror(errno));
464 while (fgets(line, sizeof line, stream)) {
467 /* Find the next CPU package. */
468 if (ovs_scan(line, "physical id%*[^:]: %u", &id)) {
470 VLOG_WARN("Counted over 64 CPU packages on this system. "
471 "Parsing %s for core count may be inaccurate.",
477 if (cpu & (1 << id)) {
478 /* We've already counted this package's cores. */
483 /* Find the number of cores for this package. */
484 while (fgets(line, sizeof line, stream)) {
487 if (ovs_scan(line, "cpu cores%*[^:]: %u", &count)) {
499 /* Returns the total number of cores on this system, or 0 if the number cannot
502 * Tries not to count hyper-threads, but may be inaccurate - particularly on
503 * platforms that do not provide /proc/cpuinfo, but also if /proc/cpuinfo is
504 * formatted different to the layout that parse_cpuinfo() expects. */
506 count_cpu_cores(void)
508 static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
509 static long int n_cores;
511 if (ovsthread_once_start(&once)) {
513 parse_cpuinfo(&n_cores);
515 n_cores = sysconf(_SC_NPROCESSORS_ONLN);
519 GetSystemInfo(&sysinfo);
520 n_cores = sysinfo.dwNumberOfProcessors;
522 ovsthread_once_done(&once);
525 return n_cores > 0 ? n_cores : 0;
532 #define MAX_KEYS (L1_SIZE * L2_SIZE)
534 /* A piece of thread-specific data. */
535 struct ovsthread_key {
536 struct list list_node; /* In 'inuse_keys' or 'free_keys'. */
537 void (*destructor)(void *); /* Called at thread exit. */
539 /* Indexes into the per-thread array in struct ovsthread_key_slots.
540 * This key's data is stored in p1[index / L2_SIZE][index % L2_SIZE]. */
544 /* Per-thread data structure. */
545 struct ovsthread_key_slots {
546 struct list list_node; /* In 'slots_list'. */
550 /* Contains "struct ovsthread_key_slots *". */
551 static pthread_key_t tsd_key;
553 /* Guards data structures below. */
554 static struct ovs_mutex key_mutex = OVS_MUTEX_INITIALIZER;
556 /* 'inuse_keys' holds "struct ovsthread_key"s that have been created and not
559 * 'free_keys' holds "struct ovsthread_key"s that have been deleted and are
560 * ready for reuse. (We keep them around only to be able to easily locate
563 * Together, 'inuse_keys' and 'free_keys' hold an ovsthread_key for every index
564 * from 0 to n_keys - 1, inclusive. */
565 static struct list inuse_keys OVS_GUARDED_BY(key_mutex)
566 = LIST_INITIALIZER(&inuse_keys);
567 static struct list free_keys OVS_GUARDED_BY(key_mutex)
568 = LIST_INITIALIZER(&free_keys);
569 static unsigned int n_keys OVS_GUARDED_BY(key_mutex);
571 /* All existing struct ovsthread_key_slots. */
572 static struct list slots_list OVS_GUARDED_BY(key_mutex)
573 = LIST_INITIALIZER(&slots_list);
576 clear_slot(struct ovsthread_key_slots *slots, unsigned int index)
578 void **p2 = slots->p1[index / L2_SIZE];
580 void **valuep = &p2[index % L2_SIZE];
581 void *value = *valuep;
590 ovsthread_key_destruct__(void *slots_)
592 struct ovsthread_key_slots *slots = slots_;
593 struct ovsthread_key *key;
597 ovs_mutex_lock(&key_mutex);
598 list_remove(&slots->list_node);
599 LIST_FOR_EACH (key, list_node, &inuse_keys) {
600 void *value = clear_slot(slots, key->index);
601 if (value && key->destructor) {
602 key->destructor(value);
606 ovs_mutex_unlock(&key_mutex);
608 for (i = 0; i < n / L2_SIZE; i++) {
614 /* Initializes '*keyp' as a thread-specific data key. The data items are
615 * initially null in all threads.
617 * If a thread exits with non-null data, then 'destructor', if nonnull, will be
618 * called passing the final data value as its argument. 'destructor' must not
619 * call any thread-specific data functions in this API.
621 * This function is similar to xpthread_key_create(). */
623 ovsthread_key_create(ovsthread_key_t *keyp, void (*destructor)(void *))
625 static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
626 struct ovsthread_key *key;
628 if (ovsthread_once_start(&once)) {
629 xpthread_key_create(&tsd_key, ovsthread_key_destruct__);
630 ovsthread_once_done(&once);
633 ovs_mutex_lock(&key_mutex);
634 if (list_is_empty(&free_keys)) {
635 key = xmalloc(sizeof *key);
636 key->index = n_keys++;
637 if (key->index >= MAX_KEYS) {
641 key = CONTAINER_OF(list_pop_back(&free_keys),
642 struct ovsthread_key, list_node);
644 list_push_back(&inuse_keys, &key->list_node);
645 key->destructor = destructor;
646 ovs_mutex_unlock(&key_mutex);
651 /* Frees 'key'. The destructor supplied to ovsthread_key_create(), if any, is
654 * This function is similar to xpthread_key_delete(). */
656 ovsthread_key_delete(ovsthread_key_t key)
658 struct ovsthread_key_slots *slots;
660 ovs_mutex_lock(&key_mutex);
662 /* Move 'key' from 'inuse_keys' to 'free_keys'. */
663 list_remove(&key->list_node);
664 list_push_back(&free_keys, &key->list_node);
666 /* Clear this slot in all threads. */
667 LIST_FOR_EACH (slots, list_node, &slots_list) {
668 clear_slot(slots, key->index);
671 ovs_mutex_unlock(&key_mutex);
675 ovsthread_key_lookup__(const struct ovsthread_key *key)
677 struct ovsthread_key_slots *slots;
680 slots = pthread_getspecific(tsd_key);
682 slots = xzalloc(sizeof *slots);
684 ovs_mutex_lock(&key_mutex);
685 pthread_setspecific(tsd_key, slots);
686 list_push_back(&slots_list, &slots->list_node);
687 ovs_mutex_unlock(&key_mutex);
690 p2 = slots->p1[key->index / L2_SIZE];
692 p2 = xzalloc(L2_SIZE * sizeof *p2);
693 slots->p1[key->index / L2_SIZE] = p2;
696 return &p2[key->index % L2_SIZE];
699 /* Sets the value of thread-specific data item 'key', in the current thread, to
702 * This function is similar to pthread_setspecific(). */
704 ovsthread_setspecific(ovsthread_key_t key, const void *value)
706 *ovsthread_key_lookup__(key) = CONST_CAST(void *, value);
709 /* Returns the value of thread-specific data item 'key' in the current thread.
711 * This function is similar to pthread_getspecific(). */
713 ovsthread_getspecific(ovsthread_key_t key)
715 return *ovsthread_key_lookup__(key);