2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
3 * Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org>
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice unmodified, this list of conditions, and the following
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.
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.
28 #include <sys/types.h>
29 #include <sys/queue.h>
35 #include "libc_private.h"
36 #include "thr_private.h"
38 /* #define DEBUG_THREAD_LIST */
39 #ifdef DEBUG_THREAD_LIST
40 #define DBG_MSG stdout_debug
45 /* List of all threads */
46 struct thread_head _thread_list = TAILQ_HEAD_INITIALIZER(_thread_list);
48 /* List of threads needing GC */
49 struct thread_head _thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
51 /* Number of active threads */
52 int _thread_active_threads = 1;
54 /* Garbage thread count. */
57 umtx_t _thr_list_lock;
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
64 #define MAX_CACHED_THREADS 100
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
71 static TAILQ_HEAD(, pthread) 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;
78 LIST_HEAD(thread_hash_head, pthread);
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)
83 static void thr_destroy(struct pthread *curthread, struct pthread *thread);
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);
97 for (i = 0; i < HASH_QUEUES; ++i)
98 LIST_INIT(&thr_hashtable[i]);
104 _thr_gc(struct pthread *curthread)
106 struct pthread *td, *td_next;
107 TAILQ_HEAD(, pthread) worklist;
109 TAILQ_INIT(&worklist);
110 THREAD_LIST_LOCK(curthread);
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 */
119 _thr_stack_free(&td->attr);
120 if (((td->tlflags & TLFLAGS_DETACHED) != 0) &&
121 (td->refcount == 0)) {
122 THR_GCLIST_REMOVE(td);
124 * The thread has detached and is no longer
125 * referenced. It is safe to remove all
126 * remnants of the thread.
129 TAILQ_INSERT_HEAD(&worklist, td, gcle);
132 THREAD_LIST_UNLOCK(curthread);
134 while ((td = TAILQ_FIRST(&worklist)) != NULL) {
135 TAILQ_REMOVE(&worklist, td, gcle);
137 * XXX we don't free initial thread, because there might
138 * have some code referencing initial thread.
140 if (td == _thr_initial) {
141 DBG_MSG("Initial thread won't be freed\n");
145 _thr_free(curthread, td);
150 _thr_alloc(struct pthread *curthread)
152 struct pthread *thread = NULL;
155 if (curthread != NULL) {
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);
164 THR_LOCK_RELEASE(curthread, &free_thread_lock);
167 if (thread == NULL) {
168 thread = malloc(sizeof(struct pthread));
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);
177 tcb = _tcb_ctor(thread, 1 /* initial tls */);
180 memset(thread, 0, sizeof(*thread));
183 thr_destroy(curthread, thread);
190 _thr_free(struct pthread *curthread, struct pthread *thread)
192 DBG_MSG("Freeing thread %p\n", thread);
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.
202 if (curthread != NULL) {
203 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
204 _tcb_dtor(thread->tcb);
205 THR_LOCK_RELEASE(curthread, &tcb_lock);
207 _tcb_dtor(thread->tcb);
210 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
211 thr_destroy(curthread, thread);
214 * Add the thread to the free thread list, this also avoids
215 * pthread id is reused too quickly, may help some buggy apps.
217 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
218 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
220 THR_LOCK_RELEASE(curthread, &free_thread_lock);
225 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
231 * Add an active thread:
233 * o Assign the thread a unique id (which GDB uses to track
235 * o Add the thread to the list of all threads and increment
236 * number of active threads.
239 _thr_link(struct pthread *curthread, struct pthread *thread)
241 THREAD_LIST_LOCK(curthread);
243 * Initialize the unique id (which GDB uses to track
244 * threads), add the thread to the list of all threads,
247 thread->uniqueid = next_uniqueid++;
248 THR_LIST_ADD(thread);
249 _thread_active_threads++;
250 THREAD_LIST_UNLOCK(curthread);
254 * Remove an active thread.
257 _thr_unlink(struct pthread *curthread, struct pthread *thread)
259 THREAD_LIST_LOCK(curthread);
260 THR_LIST_REMOVE(thread);
261 _thread_active_threads--;
262 THREAD_LIST_UNLOCK(curthread);
266 _thr_hash_add(struct pthread *thread)
268 struct thread_hash_head *head;
270 head = &thr_hashtable[THREAD_HASH(thread)];
271 LIST_INSERT_HEAD(head, thread, hle);
275 _thr_hash_remove(struct pthread *thread)
277 LIST_REMOVE(thread, hle);
281 _thr_hash_find(struct pthread *thread)
284 struct thread_hash_head *head;
286 head = &thr_hashtable[THREAD_HASH(thread)];
287 LIST_FOREACH(td, head, hle) {
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.
300 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
306 /* Invalid thread: */
309 THREAD_LIST_LOCK(curthread);
310 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
313 THREAD_LIST_UNLOCK(curthread);
315 /* Return zero if the thread exists: */
320 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
322 THREAD_LIST_LOCK(curthread);
323 _thr_ref_delete_unlocked(curthread, thread);
324 THREAD_LIST_UNLOCK(curthread);
328 _thr_ref_delete_unlocked(struct pthread *curthread __unused,
329 struct pthread *thread)
331 if (thread != NULL) {
333 if ((thread->refcount == 0) && thread->state == PS_DEAD &&
334 (thread->tlflags & TLFLAGS_DETACHED) != 0)
335 THR_GCLIST_ADD(thread);
340 _thr_find_thread(struct pthread *curthread __unused, struct pthread *thread,
343 struct pthread *pthread;
348 pthread = _thr_hash_find(thread);
350 if (include_dead == 0 && pthread->state == PS_DEAD) {
355 /* Return zero if the thread exists: */
356 return ((pthread != NULL) ? 0 : ESRCH);