xref: /freebsd/lib/libthr/thread/thr_list.c (revision edf8578117e8844e02c0121147f45e4609b30680)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
5  * Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice unmodified, this list of conditions, and the following
13  *    disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 #include <sys/types.h>
32 #include <sys/queue.h>
33 
34 #include <stdlib.h>
35 #include <string.h>
36 #include <pthread.h>
37 
38 #include "libc_private.h"
39 #include "thr_private.h"
40 #include "static_tls.h"
41 
42 /*#define DEBUG_THREAD_LIST */
43 #ifdef DEBUG_THREAD_LIST
44 #define DBG_MSG		stdout_debug
45 #else
46 #define DBG_MSG(x...)
47 #endif
48 
49 #define MAX_THREADS		100000
50 
51 /*
52  * Define a high water mark for the maximum number of threads that
53  * will be cached.  Once this level is reached, any extra threads
54  * will be free()'d.
55  */
56 #define	MAX_CACHED_THREADS	100
57 
58 /*
59  * We've got to keep track of everything that is allocated, not only
60  * to have a speedy free list, but also so they can be deallocated
61  * after a fork().
62  */
63 static TAILQ_HEAD(, pthread)	free_threadq;
64 static struct umutex		free_thread_lock = DEFAULT_UMUTEX;
65 static struct umutex		tcb_lock = DEFAULT_UMUTEX;
66 static int			free_thread_count = 0;
67 static int			inited = 0;
68 static int			total_threads;
69 
70 LIST_HEAD(thread_hash_head, pthread);
71 #define HASH_QUEUES	128
72 static struct thread_hash_head	thr_hashtable[HASH_QUEUES];
73 #define	THREAD_HASH(thrd)	(((unsigned long)thrd >> 8) % HASH_QUEUES)
74 
75 static void thr_destroy(struct pthread *curthread, struct pthread *thread);
76 
77 void
78 _thr_list_init(void)
79 {
80 	int i;
81 
82 	_gc_count = 0;
83 	total_threads = 1;
84 	_thr_urwlock_init(&_thr_list_lock);
85 	TAILQ_INIT(&_thread_list);
86 	TAILQ_INIT(&free_threadq);
87 	_thr_umutex_init(&free_thread_lock);
88 	_thr_umutex_init(&tcb_lock);
89 	if (inited) {
90 		for (i = 0; i < HASH_QUEUES; ++i)
91 			LIST_INIT(&thr_hashtable[i]);
92 	}
93 	inited = 1;
94 }
95 
96 void
97 _thr_gc(struct pthread *curthread)
98 {
99 	struct pthread *td, *td_next;
100 	TAILQ_HEAD(, pthread) worklist;
101 
102 	TAILQ_INIT(&worklist);
103 	THREAD_LIST_WRLOCK(curthread);
104 
105 	/* Check the threads waiting for GC. */
106 	TAILQ_FOREACH_SAFE(td, &_thread_gc_list, gcle, td_next) {
107 		if (td->tid != TID_TERMINATED) {
108 			/* make sure we are not still in userland */
109 			continue;
110 		}
111 		_thr_stack_free(&td->attr);
112 		THR_GCLIST_REMOVE(td);
113 		TAILQ_INSERT_HEAD(&worklist, td, gcle);
114 	}
115 	THREAD_LIST_UNLOCK(curthread);
116 
117 	while ((td = TAILQ_FIRST(&worklist)) != NULL) {
118 		TAILQ_REMOVE(&worklist, td, gcle);
119 		/*
120 		 * XXX we don't free initial thread, because there might
121 		 * have some code referencing initial thread.
122 		 */
123 		if (td == _thr_initial) {
124 			DBG_MSG("Initial thread won't be freed\n");
125 			continue;
126 		}
127 
128 		_thr_free(curthread, td);
129 	}
130 }
131 
132 struct pthread *
133 _thr_alloc(struct pthread *curthread)
134 {
135 	struct pthread	*thread = NULL;
136 	struct tcb	*tcb;
137 
138 	if (curthread != NULL) {
139 		if (GC_NEEDED())
140 			_thr_gc(curthread);
141 		if (free_thread_count > 0) {
142 			THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
143 			if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
144 				TAILQ_REMOVE(&free_threadq, thread, tle);
145 				free_thread_count--;
146 			}
147 			THR_LOCK_RELEASE(curthread, &free_thread_lock);
148 		}
149 	}
150 	if (thread == NULL) {
151 		if (total_threads > MAX_THREADS)
152 			return (NULL);
153 		atomic_fetchadd_int(&total_threads, 1);
154 		thread = calloc(1, sizeof(struct pthread));
155 		if (thread == NULL) {
156 			atomic_fetchadd_int(&total_threads, -1);
157 			return (NULL);
158 		}
159 		if ((thread->sleepqueue = _sleepq_alloc()) == NULL ||
160 		    (thread->wake_addr = _thr_alloc_wake_addr()) == NULL) {
161 			thr_destroy(curthread, thread);
162 			atomic_fetchadd_int(&total_threads, -1);
163 			return (NULL);
164 		}
165 	} else {
166 		bzero(&thread->_pthread_startzero,
167 			__rangeof(struct pthread, _pthread_startzero, _pthread_endzero));
168 	}
169 	if (curthread != NULL) {
170 		THR_LOCK_ACQUIRE(curthread, &tcb_lock);
171 		tcb = _tcb_ctor(thread, 0 /* not initial tls */);
172 		THR_LOCK_RELEASE(curthread, &tcb_lock);
173 	} else {
174 		tcb = _tcb_ctor(thread, 1 /* initial tls */);
175 	}
176 	if (tcb != NULL) {
177 		thread->tcb = tcb;
178 	} else {
179 		thr_destroy(curthread, thread);
180 		atomic_fetchadd_int(&total_threads, -1);
181 		thread = NULL;
182 	}
183 	return (thread);
184 }
185 
186 void
187 _thr_free(struct pthread *curthread, struct pthread *thread)
188 {
189 	DBG_MSG("Freeing thread %p\n", thread);
190 
191 	/*
192 	 * Always free tcb, as we only know it is part of RTLD TLS
193 	 * block, but don't know its detail and can not assume how
194 	 * it works, so better to avoid caching it here.
195 	 */
196 	if (curthread != NULL) {
197 		THR_LOCK_ACQUIRE(curthread, &tcb_lock);
198 		_tcb_dtor(thread->tcb);
199 		THR_LOCK_RELEASE(curthread, &tcb_lock);
200 	} else {
201 		_tcb_dtor(thread->tcb);
202 	}
203 	thread->tcb = NULL;
204 	if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
205 		thr_destroy(curthread, thread);
206 		atomic_fetchadd_int(&total_threads, -1);
207 	} else {
208 		/*
209 		 * Add the thread to the free thread list, this also avoids
210 		 * pthread id is reused too quickly, may help some buggy apps.
211 		 */
212 		THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
213 		TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
214 		free_thread_count++;
215 		THR_LOCK_RELEASE(curthread, &free_thread_lock);
216 	}
217 }
218 
219 static void
220 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
221 {
222 	if (thread->sleepqueue != NULL)
223 		_sleepq_free(thread->sleepqueue);
224 	if (thread->wake_addr != NULL)
225 		_thr_release_wake_addr(thread->wake_addr);
226 	free(thread);
227 }
228 
229 /*
230  * Add the thread to the list of all threads and increment
231  * number of active threads.
232  */
233 void
234 _thr_link(struct pthread *curthread, struct pthread *thread)
235 {
236 	THREAD_LIST_WRLOCK(curthread);
237 	THR_LIST_ADD(thread);
238 	THREAD_LIST_UNLOCK(curthread);
239 	atomic_add_int(&_thread_active_threads, 1);
240 }
241 
242 /*
243  * Remove an active thread.
244  */
245 void
246 _thr_unlink(struct pthread *curthread, struct pthread *thread)
247 {
248 	THREAD_LIST_WRLOCK(curthread);
249 	THR_LIST_REMOVE(thread);
250 	THREAD_LIST_UNLOCK(curthread);
251 	atomic_add_int(&_thread_active_threads, -1);
252 }
253 
254 void
255 _thr_hash_add(struct pthread *thread)
256 {
257 	struct thread_hash_head *head;
258 
259 	head = &thr_hashtable[THREAD_HASH(thread)];
260 	LIST_INSERT_HEAD(head, thread, hle);
261 }
262 
263 void
264 _thr_hash_remove(struct pthread *thread)
265 {
266 	LIST_REMOVE(thread, hle);
267 }
268 
269 struct pthread *
270 _thr_hash_find(struct pthread *thread)
271 {
272 	struct pthread *td;
273 	struct thread_hash_head *head;
274 
275 	head = &thr_hashtable[THREAD_HASH(thread)];
276 	LIST_FOREACH(td, head, hle) {
277 		if (td == thread)
278 			return (thread);
279 	}
280 	return (NULL);
281 }
282 
283 /*
284  * Find a thread in the linked list of active threads and add a reference
285  * to it.  Threads with positive reference counts will not be deallocated
286  * until all references are released.
287  */
288 int
289 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
290     int include_dead)
291 {
292 	int ret;
293 
294 	if (thread == NULL)
295 		/* Invalid thread: */
296 		return (EINVAL);
297 
298 	if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
299 		thread->refcount++;
300 		THR_CRITICAL_ENTER(curthread);
301 		THR_THREAD_UNLOCK(curthread, thread);
302 	}
303 
304 	/* Return zero if the thread exists: */
305 	return (ret);
306 }
307 
308 void
309 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
310 {
311 	THR_THREAD_LOCK(curthread, thread);
312 	thread->refcount--;
313 	_thr_try_gc(curthread, thread);
314 	THR_CRITICAL_LEAVE(curthread);
315 }
316 
317 /* entered with thread lock held, exit with thread lock released */
318 void
319 _thr_try_gc(struct pthread *curthread, struct pthread *thread)
320 {
321 	if (THR_SHOULD_GC(thread)) {
322 		THR_REF_ADD(curthread, thread);
323 		THR_THREAD_UNLOCK(curthread, thread);
324 		THREAD_LIST_WRLOCK(curthread);
325 		THR_THREAD_LOCK(curthread, thread);
326 		THR_REF_DEL(curthread, thread);
327 		if (THR_SHOULD_GC(thread)) {
328 			THR_LIST_REMOVE(thread);
329 			THR_GCLIST_ADD(thread);
330 		}
331 		THR_THREAD_UNLOCK(curthread, thread);
332 		THREAD_LIST_UNLOCK(curthread);
333 	} else {
334 		THR_THREAD_UNLOCK(curthread, thread);
335 	}
336 }
337 
338 /* return with thread lock held if thread is found */
339 int
340 _thr_find_thread(struct pthread *curthread, struct pthread *thread,
341     int include_dead)
342 {
343 	struct pthread *pthread;
344 	int ret;
345 
346 	if (thread == NULL)
347 		return (EINVAL);
348 
349 	ret = 0;
350 	THREAD_LIST_RDLOCK(curthread);
351 	pthread = _thr_hash_find(thread);
352 	if (pthread) {
353 		THR_THREAD_LOCK(curthread, pthread);
354 		if (include_dead == 0 && pthread->state == PS_DEAD) {
355 			THR_THREAD_UNLOCK(curthread, pthread);
356 			ret = ESRCH;
357 		}
358 	} else {
359 		ret = ESRCH;
360 	}
361 	THREAD_LIST_UNLOCK(curthread);
362 	return (ret);
363 }
364 
365 #include "pthread_tls.h"
366 
367 static void
368 thr_distribute_static_tls(uintptr_t tlsbase, void *src, size_t len,
369     size_t total_len)
370 {
371 
372 	memcpy((void *)tlsbase, src, len);
373 	memset((char *)tlsbase + len, 0, total_len - len);
374 }
375 
376 void
377 __pthread_distribute_static_tls(size_t offset, void *src, size_t len,
378     size_t total_len)
379 {
380 	struct pthread *curthread, *thrd;
381 	uintptr_t tlsbase;
382 
383 	if (!_thr_is_inited()) {
384 		tlsbase = _libc_get_static_tls_base(offset);
385 		thr_distribute_static_tls(tlsbase, src, len, total_len);
386 		return;
387 	}
388 	curthread = _get_curthread();
389 	THREAD_LIST_RDLOCK(curthread);
390 	TAILQ_FOREACH(thrd, &_thread_list, tle) {
391 		tlsbase = _get_static_tls_base(thrd, offset);
392 		thr_distribute_static_tls(tlsbase, src, len, total_len);
393 	}
394 	THREAD_LIST_UNLOCK(curthread);
395 }
396