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/types.h>
29 #include <sys/queue.h>
30
31 #include <stdlib.h>
32 #include <string.h>
33 #include <pthread.h>
34
35 #include "libc_private.h"
36 #include "thr_private.h"
37
38 /* #define DEBUG_THREAD_LIST */
39 #ifdef DEBUG_THREAD_LIST
40 #define DBG_MSG stdout_debug
41 #else
42 #define DBG_MSG(x...)
43 #endif
44
45 /* List of all threads */
46 struct thread_head _thread_list = TAILQ_HEAD_INITIALIZER(_thread_list);
47
48 /* List of threads needing GC */
49 struct thread_head _thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
50
51 /* Number of active threads */
52 int _thread_active_threads = 1;
53
54 /* Garbage thread count. */
55 int _thr_gc_count;
56
57 umtx_t _thr_list_lock;
58
59 /*
60 * Define a high water mark for the maximum number of threads that
61 * will be cached. Once this level is reached, any extra threads
62 * will be free()'d.
63 */
64 #define MAX_CACHED_THREADS 100
65
66 /*
67 * We've got to keep track of everything that is allocated, not only
68 * to have a speedy free list, but also so they can be deallocated
69 * after a fork().
70 */
71 static TAILQ_HEAD(, __pthread_s) free_threadq;
72 static umtx_t free_thread_lock;
73 static umtx_t tcb_lock;
74 static int free_thread_count = 0;
75 static int inited = 0;
76 static u_int64_t next_uniqueid = 1;
77
78 LIST_HEAD(thread_hash_head, __pthread_s);
79 #define HASH_QUEUES 128
80 static struct thread_hash_head thr_hashtable[HASH_QUEUES];
81 #define THREAD_HASH(thrd) (((unsigned long)thrd >> 12) % HASH_QUEUES)
82
83 static void thr_destroy(pthread_t curthread, pthread_t thread);
84
85 void
_thr_list_init(void)86 _thr_list_init(void)
87 {
88 int i;
89
90 _thr_gc_count = 0;
91 _thr_umtx_init(&_thr_list_lock);
92 TAILQ_INIT(&_thread_list);
93 TAILQ_INIT(&free_threadq);
94 _thr_umtx_init(&free_thread_lock);
95 _thr_umtx_init(&tcb_lock);
96 if (inited) {
97 for (i = 0; i < HASH_QUEUES; ++i)
98 LIST_INIT(&thr_hashtable[i]);
99 }
100 inited = 1;
101 }
102
103 void
_thr_gc(pthread_t curthread)104 _thr_gc(pthread_t curthread)
105 {
106 pthread_t td, td_next;
107 TAILQ_HEAD(, __pthread_s) worklist;
108
109 TAILQ_INIT(&worklist);
110 THREAD_LIST_LOCK(curthread);
111
112 /* Check the threads waiting for GC. */
113 for (td = TAILQ_FIRST(&_thread_gc_list); td != NULL; td = td_next) {
114 td_next = TAILQ_NEXT(td, gcle);
115 if (td->terminated == 0) {
116 /* make sure we are not still in userland */
117 continue;
118 }
119 _thr_stack_free(&td->attr);
120 if (((td->tlflags & TLFLAGS_DETACHED) != 0) &&
121 (td->refcount == 0)) {
122 THR_GCLIST_REMOVE(td);
123 /*
124 * The thread has detached and is no longer
125 * referenced. It is safe to remove all
126 * remnants of the thread.
127 */
128 THR_LIST_REMOVE(td);
129 TAILQ_INSERT_HEAD(&worklist, td, gcle);
130 }
131 }
132 THREAD_LIST_UNLOCK(curthread);
133
134 while ((td = TAILQ_FIRST(&worklist)) != NULL) {
135 TAILQ_REMOVE(&worklist, td, gcle);
136 /*
137 * XXX we don't free initial thread, because there might
138 * have some code referencing initial thread.
139 */
140 if (td == _thr_initial) {
141 DBG_MSG("Initial thread won't be freed\n");
142 continue;
143 }
144
145 _thr_free(curthread, td);
146 }
147 }
148
149 pthread_t
_thr_alloc(pthread_t curthread)150 _thr_alloc(pthread_t curthread)
151 {
152 pthread_t thread = NULL;
153 struct tls_tcb *tcb;
154
155 if (curthread != NULL) {
156 if (GC_NEEDED())
157 _thr_gc(curthread);
158 if (free_thread_count > 0) {
159 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
160 if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
161 TAILQ_REMOVE(&free_threadq, thread, tle);
162 free_thread_count--;
163 }
164 THR_LOCK_RELEASE(curthread, &free_thread_lock);
165 }
166 }
167 if (thread == NULL) {
168 thread = __malloc(sizeof(struct __pthread_s));
169 if (thread == NULL)
170 return (NULL);
171 }
172 if (curthread != NULL) {
173 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
174 tcb = _tcb_ctor(thread, 0 /* not initial tls */);
175 THR_LOCK_RELEASE(curthread, &tcb_lock);
176 } else {
177 tcb = _tcb_ctor(thread, 1 /* initial tls */);
178 }
179 if (tcb != NULL) {
180 memset(thread, 0, sizeof(*thread));
181 thread->tcb = tcb;
182 } else {
183 thr_destroy(curthread, thread);
184 thread = NULL;
185 }
186 return (thread);
187 }
188
189 void
_thr_free(pthread_t curthread,pthread_t thread)190 _thr_free(pthread_t curthread, pthread_t thread)
191 {
192 DBG_MSG("Freeing thread %p\n", thread);
193 if (thread->name) {
194 __free(thread->name);
195 thread->name = NULL;
196 }
197 /*
198 * Always free tcb, as we only know it is part of RTLD TLS
199 * block, but don't know its detail and can not assume how
200 * it works, so better to avoid caching it here.
201 */
202 if (curthread != NULL) {
203 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
204 _tcb_dtor(thread->tcb);
205 THR_LOCK_RELEASE(curthread, &tcb_lock);
206 } else {
207 _tcb_dtor(thread->tcb);
208 }
209 thread->tcb = NULL;
210 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
211 thr_destroy(curthread, thread);
212 } else {
213 /*
214 * Add the thread to the free thread list, this also avoids
215 * pthread id is reused too quickly, may help some buggy apps.
216 */
217 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
218 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
219 free_thread_count++;
220 THR_LOCK_RELEASE(curthread, &free_thread_lock);
221 }
222 }
223
224 static void
thr_destroy(pthread_t curthread __unused,pthread_t thread)225 thr_destroy(pthread_t curthread __unused, pthread_t thread)
226 {
227 __free(thread);
228 }
229
230 /*
231 * Add an active thread:
232 *
233 * o Assign the thread a unique id (which GDB uses to track
234 * threads.
235 * o Add the thread to the list of all threads and increment
236 * number of active threads.
237 */
238 void
_thr_link(pthread_t curthread,pthread_t thread)239 _thr_link(pthread_t curthread, pthread_t thread)
240 {
241 THREAD_LIST_LOCK(curthread);
242 /*
243 * Initialize the unique id (which GDB uses to track
244 * threads), add the thread to the list of all threads,
245 * and
246 */
247 thread->uniqueid = next_uniqueid++;
248 THR_LIST_ADD(thread);
249 _thread_active_threads++;
250 THREAD_LIST_UNLOCK(curthread);
251 }
252
253 /*
254 * Remove an active thread.
255 */
256 void
_thr_unlink(pthread_t curthread,pthread_t thread)257 _thr_unlink(pthread_t curthread, pthread_t thread)
258 {
259 THREAD_LIST_LOCK(curthread);
260 THR_LIST_REMOVE(thread);
261 _thread_active_threads--;
262 THREAD_LIST_UNLOCK(curthread);
263 }
264
265 void
_thr_hash_add(pthread_t thread)266 _thr_hash_add(pthread_t thread)
267 {
268 struct thread_hash_head *head;
269
270 head = &thr_hashtable[THREAD_HASH(thread)];
271 LIST_INSERT_HEAD(head, thread, hle);
272 }
273
274 void
_thr_hash_remove(pthread_t thread)275 _thr_hash_remove(pthread_t thread)
276 {
277 LIST_REMOVE(thread, hle);
278 }
279
280 pthread_t
_thr_hash_find(pthread_t thread)281 _thr_hash_find(pthread_t thread)
282 {
283 pthread_t td;
284 struct thread_hash_head *head;
285
286 head = &thr_hashtable[THREAD_HASH(thread)];
287 LIST_FOREACH(td, head, hle) {
288 if (td == thread)
289 return (thread);
290 }
291 return (NULL);
292 }
293
294 /*
295 * Find a thread in the linked list of active threads and add a reference
296 * to it. Threads with positive reference counts will not be deallocated
297 * until all references are released.
298 */
299 int
_thr_ref_add(pthread_t curthread,pthread_t thread,int include_dead)300 _thr_ref_add(pthread_t curthread, pthread_t thread,
301 int include_dead)
302 {
303 int ret;
304
305 if (thread == NULL)
306 /* Invalid thread: */
307 return (EINVAL);
308
309 THREAD_LIST_LOCK(curthread);
310 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
311 thread->refcount++;
312 }
313 THREAD_LIST_UNLOCK(curthread);
314
315 /* Return zero if the thread exists: */
316 return (ret);
317 }
318
319 void
_thr_ref_delete(pthread_t curthread,pthread_t thread)320 _thr_ref_delete(pthread_t curthread, pthread_t thread)
321 {
322 THREAD_LIST_LOCK(curthread);
323 _thr_ref_delete_unlocked(curthread, thread);
324 THREAD_LIST_UNLOCK(curthread);
325 }
326
327 void
_thr_ref_delete_unlocked(pthread_t curthread __unused,pthread_t thread)328 _thr_ref_delete_unlocked(pthread_t curthread __unused, pthread_t thread)
329 {
330 if (thread != NULL) {
331 thread->refcount--;
332 if ((thread->refcount == 0) && thread->state == PS_DEAD &&
333 (thread->tlflags & TLFLAGS_DETACHED) != 0)
334 THR_GCLIST_ADD(thread);
335 }
336 }
337
338 int
_thr_find_thread(pthread_t curthread __unused,pthread_t thread,int include_dead)339 _thr_find_thread(pthread_t curthread __unused, pthread_t thread,
340 int include_dead)
341 {
342 pthread_t pthread;
343
344 if (thread == NULL)
345 return (EINVAL);
346
347 pthread = _thr_hash_find(thread);
348 if (pthread) {
349 if (include_dead == 0 && pthread->state == PS_DEAD) {
350 pthread = NULL;
351 }
352 }
353
354 /* Return zero if the thread exists: */
355 return ((pthread != NULL) ? 0 : ESRCH);
356 }
357