1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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__FBSDID("$FreeBSD$");
32
33#include <sys/types.h>
34#include <sys/queue.h>
35
36#include <stdlib.h>
37#include <string.h>
38#include <pthread.h>
39
40#include "libc_private.h"
41#include "thr_private.h"
42#include "static_tls.h"
43
44/*#define DEBUG_THREAD_LIST */
45#ifdef DEBUG_THREAD_LIST
46#define DBG_MSG		stdout_debug
47#else
48#define DBG_MSG(x...)
49#endif
50
51#define MAX_THREADS		100000
52
53/*
54 * Define a high water mark for the maximum number of threads that
55 * will be cached.  Once this level is reached, any extra threads
56 * will be free()'d.
57 */
58#define	MAX_CACHED_THREADS	100
59
60/*
61 * We've got to keep track of everything that is allocated, not only
62 * to have a speedy free list, but also so they can be deallocated
63 * after a fork().
64 */
65static TAILQ_HEAD(, pthread)	free_threadq;
66static struct umutex		free_thread_lock = DEFAULT_UMUTEX;
67static struct umutex		tcb_lock = DEFAULT_UMUTEX;
68static int			free_thread_count = 0;
69static int			inited = 0;
70static int			total_threads;
71
72LIST_HEAD(thread_hash_head, pthread);
73#define HASH_QUEUES	128
74static struct thread_hash_head	thr_hashtable[HASH_QUEUES];
75#define	THREAD_HASH(thrd)	(((unsigned long)thrd >> 8) % HASH_QUEUES)
76
77static void thr_destroy(struct pthread *curthread, struct pthread *thread);
78
79void
80_thr_list_init(void)
81{
82	int i;
83
84	_gc_count = 0;
85	total_threads = 1;
86	_thr_urwlock_init(&_thr_list_lock);
87	TAILQ_INIT(&_thread_list);
88	TAILQ_INIT(&free_threadq);
89	_thr_umutex_init(&free_thread_lock);
90	_thr_umutex_init(&tcb_lock);
91	if (inited) {
92		for (i = 0; i < HASH_QUEUES; ++i)
93			LIST_INIT(&thr_hashtable[i]);
94	}
95	inited = 1;
96}
97
98void
99_thr_gc(struct pthread *curthread)
100{
101	struct pthread *td, *td_next;
102	TAILQ_HEAD(, pthread) worklist;
103
104	TAILQ_INIT(&worklist);
105	THREAD_LIST_WRLOCK(curthread);
106
107	/* Check the threads waiting for GC. */
108	TAILQ_FOREACH_SAFE(td, &_thread_gc_list, gcle, td_next) {
109		if (td->tid != TID_TERMINATED) {
110			/* make sure we are not still in userland */
111			continue;
112		}
113		_thr_stack_free(&td->attr);
114		THR_GCLIST_REMOVE(td);
115		TAILQ_INSERT_HEAD(&worklist, td, gcle);
116	}
117	THREAD_LIST_UNLOCK(curthread);
118
119	while ((td = TAILQ_FIRST(&worklist)) != NULL) {
120		TAILQ_REMOVE(&worklist, td, gcle);
121		/*
122		 * XXX we don't free initial thread, because there might
123		 * have some code referencing initial thread.
124		 */
125		if (td == _thr_initial) {
126			DBG_MSG("Initial thread won't be freed\n");
127			continue;
128		}
129
130		_thr_free(curthread, td);
131	}
132}
133
134struct pthread *
135_thr_alloc(struct pthread *curthread)
136{
137	struct pthread	*thread = NULL;
138	struct tcb	*tcb;
139
140	if (curthread != NULL) {
141		if (GC_NEEDED())
142			_thr_gc(curthread);
143		if (free_thread_count > 0) {
144			THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
145			if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
146				TAILQ_REMOVE(&free_threadq, thread, tle);
147				free_thread_count--;
148			}
149			THR_LOCK_RELEASE(curthread, &free_thread_lock);
150		}
151	}
152	if (thread == NULL) {
153		if (total_threads > MAX_THREADS)
154			return (NULL);
155		atomic_fetchadd_int(&total_threads, 1);
156		thread = calloc(1, sizeof(struct pthread));
157		if (thread == NULL) {
158			atomic_fetchadd_int(&total_threads, -1);
159			return (NULL);
160		}
161		if ((thread->sleepqueue = _sleepq_alloc()) == NULL ||
162		    (thread->wake_addr = _thr_alloc_wake_addr()) == NULL) {
163			thr_destroy(curthread, thread);
164			atomic_fetchadd_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_fetchadd_int(&total_threads, -1);
183		thread = NULL;
184	}
185	return (thread);
186}
187
188void
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_fetchadd_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
221static void
222thr_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	free(thread);
229}
230
231/*
232 * Add the thread to the list of all threads and increment
233 * number of active threads.
234 */
235void
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 */
247void
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
256void
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
265void
266_thr_hash_remove(struct pthread *thread)
267{
268	LIST_REMOVE(thread, hle);
269}
270
271struct pthread *
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 */
290int
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
310void
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 */
320void
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 */
341int
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#include "pthread_tls.h"
368
369static void
370thr_distribute_static_tls(uintptr_t tlsbase, void *src, size_t len,
371    size_t total_len)
372{
373
374	memcpy((void *)tlsbase, src, len);
375	memset((char *)tlsbase + len, 0, total_len - len);
376}
377
378void
379__pthread_distribute_static_tls(size_t offset, void *src, size_t len,
380    size_t total_len)
381{
382	struct pthread *curthread, *thrd;
383	uintptr_t tlsbase;
384
385	if (!_thr_is_inited()) {
386		tlsbase = _libc_get_static_tls_base(offset);
387		thr_distribute_static_tls(tlsbase, src, len, total_len);
388		return;
389	}
390	curthread = _get_curthread();
391	THREAD_LIST_RDLOCK(curthread);
392	TAILQ_FOREACH(thrd, &_thread_list, tle) {
393		tlsbase = _get_static_tls_base(thrd, offset);
394		thr_distribute_static_tls(tlsbase, src, len, total_len);
395	}
396	THREAD_LIST_UNLOCK(curthread);
397}
398