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/types.h>
31 #include <sys/queue.h>
32
33 #include <machine/tls.h>
34
35 #include <stdlib.h>
36 #include <string.h>
37 #include <pthread.h>
38
39 #include "libc_private.h"
40 #include "thr_private.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
_thr_list_init(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
_thr_gc(struct pthread * curthread)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 *
_thr_alloc(struct pthread * curthread)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_add_int(&total_threads, 1);
154 thread = __thr_aligned_alloc_offset(_Alignof(struct pthread),
155 sizeof(struct pthread), 0);
156 if (thread == NULL) {
157 atomic_add_int(&total_threads, -1);
158 return (NULL);
159 }
160 memset(thread, 0, sizeof(*thread));
161 if ((thread->sleepqueue = _sleepq_alloc()) == NULL ||
162 (thread->wake_addr = _thr_alloc_wake_addr()) == NULL) {
163 thr_destroy(curthread, thread);
164 atomic_add_int(&total_threads, -1);
165 return (NULL);
166 }
167 } else {
168 bzero(&thread->_pthread_startzero,
169 __rangeof(struct pthread, _pthread_startzero, _pthread_endzero));
170 }
171 if (curthread != NULL) {
172 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
173 tcb = _tcb_ctor(thread, 0 /* not initial tls */);
174 THR_LOCK_RELEASE(curthread, &tcb_lock);
175 } else {
176 tcb = _tcb_ctor(thread, 1 /* initial tls */);
177 }
178 if (tcb != NULL) {
179 thread->tcb = tcb;
180 } else {
181 thr_destroy(curthread, thread);
182 atomic_add_int(&total_threads, -1);
183 thread = NULL;
184 }
185 return (thread);
186 }
187
188 void
_thr_free(struct pthread * curthread,struct pthread * thread)189 _thr_free(struct pthread *curthread, struct pthread *thread)
190 {
191 DBG_MSG("Freeing thread %p\n", thread);
192
193 /*
194 * Always free tcb, as we only know it is part of RTLD TLS
195 * block, but don't know its detail and can not assume how
196 * it works, so better to avoid caching it here.
197 */
198 if (curthread != NULL) {
199 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
200 _tcb_dtor(thread->tcb);
201 THR_LOCK_RELEASE(curthread, &tcb_lock);
202 } else {
203 _tcb_dtor(thread->tcb);
204 }
205 thread->tcb = NULL;
206 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
207 thr_destroy(curthread, thread);
208 atomic_add_int(&total_threads, -1);
209 } else {
210 /*
211 * Add the thread to the free thread list, this also avoids
212 * pthread id is reused too quickly, may help some buggy apps.
213 */
214 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
215 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
216 free_thread_count++;
217 THR_LOCK_RELEASE(curthread, &free_thread_lock);
218 }
219 }
220
221 static void
thr_destroy(struct pthread * curthread __unused,struct pthread * thread)222 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
223 {
224 if (thread->sleepqueue != NULL)
225 _sleepq_free(thread->sleepqueue);
226 if (thread->wake_addr != NULL)
227 _thr_release_wake_addr(thread->wake_addr);
228 __thr_free(thread);
229 }
230
231 /*
232 * Add the thread to the list of all threads and increment
233 * number of active threads.
234 */
235 void
_thr_link(struct pthread * curthread,struct pthread * thread)236 _thr_link(struct pthread *curthread, struct pthread *thread)
237 {
238 THREAD_LIST_WRLOCK(curthread);
239 THR_LIST_ADD(thread);
240 THREAD_LIST_UNLOCK(curthread);
241 atomic_add_int(&_thread_active_threads, 1);
242 }
243
244 /*
245 * Remove an active thread.
246 */
247 void
_thr_unlink(struct pthread * curthread,struct pthread * thread)248 _thr_unlink(struct pthread *curthread, struct pthread *thread)
249 {
250 THREAD_LIST_WRLOCK(curthread);
251 THR_LIST_REMOVE(thread);
252 THREAD_LIST_UNLOCK(curthread);
253 atomic_add_int(&_thread_active_threads, -1);
254 }
255
256 void
_thr_hash_add(struct pthread * thread)257 _thr_hash_add(struct pthread *thread)
258 {
259 struct thread_hash_head *head;
260
261 head = &thr_hashtable[THREAD_HASH(thread)];
262 LIST_INSERT_HEAD(head, thread, hle);
263 }
264
265 void
_thr_hash_remove(struct pthread * thread)266 _thr_hash_remove(struct pthread *thread)
267 {
268 LIST_REMOVE(thread, hle);
269 }
270
271 struct pthread *
_thr_hash_find(struct pthread * thread)272 _thr_hash_find(struct pthread *thread)
273 {
274 struct pthread *td;
275 struct thread_hash_head *head;
276
277 head = &thr_hashtable[THREAD_HASH(thread)];
278 LIST_FOREACH(td, head, hle) {
279 if (td == thread)
280 return (thread);
281 }
282 return (NULL);
283 }
284
285 /*
286 * Find a thread in the linked list of active threads and add a reference
287 * to it. Threads with positive reference counts will not be deallocated
288 * until all references are released.
289 */
290 int
_thr_ref_add(struct pthread * curthread,struct pthread * thread,int include_dead)291 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
292 int include_dead)
293 {
294 int ret;
295
296 if (thread == NULL)
297 /* Invalid thread: */
298 return (EINVAL);
299
300 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
301 thread->refcount++;
302 THR_CRITICAL_ENTER(curthread);
303 THR_THREAD_UNLOCK(curthread, thread);
304 }
305
306 /* Return zero if the thread exists: */
307 return (ret);
308 }
309
310 void
_thr_ref_delete(struct pthread * curthread,struct pthread * thread)311 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
312 {
313 THR_THREAD_LOCK(curthread, thread);
314 thread->refcount--;
315 _thr_try_gc(curthread, thread);
316 THR_CRITICAL_LEAVE(curthread);
317 }
318
319 /* entered with thread lock held, exit with thread lock released */
320 void
_thr_try_gc(struct pthread * curthread,struct pthread * thread)321 _thr_try_gc(struct pthread *curthread, struct pthread *thread)
322 {
323 if (THR_SHOULD_GC(thread)) {
324 THR_REF_ADD(curthread, thread);
325 THR_THREAD_UNLOCK(curthread, thread);
326 THREAD_LIST_WRLOCK(curthread);
327 THR_THREAD_LOCK(curthread, thread);
328 THR_REF_DEL(curthread, thread);
329 if (THR_SHOULD_GC(thread)) {
330 THR_LIST_REMOVE(thread);
331 THR_GCLIST_ADD(thread);
332 }
333 THR_THREAD_UNLOCK(curthread, thread);
334 THREAD_LIST_UNLOCK(curthread);
335 } else {
336 THR_THREAD_UNLOCK(curthread, thread);
337 }
338 }
339
340 /* return with thread lock held if thread is found */
341 int
_thr_find_thread(struct pthread * curthread,struct pthread * thread,int include_dead)342 _thr_find_thread(struct pthread *curthread, struct pthread *thread,
343 int include_dead)
344 {
345 struct pthread *pthread;
346 int ret;
347
348 if (thread == NULL)
349 return (EINVAL);
350
351 ret = 0;
352 THREAD_LIST_RDLOCK(curthread);
353 pthread = _thr_hash_find(thread);
354 if (pthread) {
355 THR_THREAD_LOCK(curthread, pthread);
356 if (include_dead == 0 && pthread->state == PS_DEAD) {
357 THR_THREAD_UNLOCK(curthread, pthread);
358 ret = ESRCH;
359 }
360 } else {
361 ret = ESRCH;
362 }
363 THREAD_LIST_UNLOCK(curthread);
364 return (ret);
365 }
366
367 static void
thr_distribute_static_tls(char * tlsbase,void * src,size_t len,size_t total_len)368 thr_distribute_static_tls(char *tlsbase, void *src, size_t len,
369 size_t total_len)
370 {
371
372 memcpy(tlsbase, src, len);
373 memset(tlsbase + len, 0, total_len - len);
374 }
375
376 void
__pthread_distribute_static_tls(size_t offset,void * src,size_t len,size_t total_len)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 char *tlsbase;
382
383 if (!_thr_is_inited()) {
384 #ifdef TLS_VARIANT_I
385 tlsbase = (char *)_tcb_get() + offset;
386 #else
387 tlsbase = (char *)_tcb_get() - offset;
388 #endif
389 thr_distribute_static_tls(tlsbase, src, len, total_len);
390 return;
391 }
392 curthread = _get_curthread();
393 THREAD_LIST_RDLOCK(curthread);
394 TAILQ_FOREACH(thrd, &_thread_list, tle) {
395 #ifdef TLS_VARIANT_I
396 tlsbase = (char *)thrd->tcb + offset;
397 #else
398 tlsbase = (char *)thrd->tcb - offset;
399 #endif
400 thr_distribute_static_tls(tlsbase, src, len, total_len);
401 }
402 THREAD_LIST_UNLOCK(curthread);
403 }
404