1 /*
2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
3 * Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice unmodified, this list of conditions, and the following
11 * disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30
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
_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_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
_thr_free(struct pthread * curthread,struct pthread * thread)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
thr_destroy(struct pthread * curthread __unused,struct pthread * thread)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
_thr_link(struct pthread * curthread,struct pthread * thread)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
_thr_unlink(struct pthread * curthread,struct pthread * thread)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
_thr_hash_add(struct pthread * thread)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
_thr_hash_remove(struct pthread * thread)264 _thr_hash_remove(struct pthread *thread)
265 {
266 LIST_REMOVE(thread, hle);
267 }
268
269 struct pthread *
_thr_hash_find(struct pthread * thread)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
_thr_ref_add(struct pthread * curthread,struct pthread * thread,int include_dead)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
_thr_ref_delete(struct pthread * curthread,struct pthread * thread)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
_thr_try_gc(struct pthread * curthread,struct pthread * thread)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
_thr_find_thread(struct pthread * curthread,struct pthread * thread,int include_dead)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
thr_distribute_static_tls(uintptr_t tlsbase,void * src,size_t len,size_t total_len)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
__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 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