thr_find_thread.c revision 165967 
1/*
2 * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
3 * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
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, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the author nor the names of any co-contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * $FreeBSD: head/lib/libkse/thread/thr_find_thread.c 165967 2007-01-12 07:26:21Z imp $
31 */
32#include <errno.h>
33#include <pthread.h>
34#include "thr_private.h"
35
36/*
37 * Find a thread in the linked list of active threads and add a reference
38 * to it.  Threads with positive reference counts will not be deallocated
39 * until all references are released.
40 */
41int
42_thr_ref_add(struct pthread *curthread, struct pthread *thread,
43    int include_dead)
44{
45	kse_critical_t crit;
46	struct pthread *pthread;
47	struct kse *curkse;
48
49	if (thread == NULL)
50		/* Invalid thread: */
51		return (EINVAL);
52
53	crit = _kse_critical_enter();
54	curkse = _get_curkse();
55	KSE_LOCK_ACQUIRE(curkse, &_thread_list_lock);
56	pthread = _thr_hash_find(thread);
57	if (pthread) {
58		if ((include_dead == 0) &&
59		    ((pthread->state == PS_DEAD) ||
60		    ((pthread->state == PS_DEADLOCK) ||
61		    ((pthread->flags & THR_FLAGS_EXITING) != 0))))
62			pthread = NULL;
63		else {
64			pthread->refcount++;
65			if (curthread != NULL)
66				curthread->critical_count++;
67		}
68	}
69	KSE_LOCK_RELEASE(curkse, &_thread_list_lock);
70	_kse_critical_leave(crit);
71
72	/* Return zero if the thread exists: */
73	return ((pthread != NULL) ? 0 : ESRCH);
74}
75
76void
77_thr_ref_delete(struct pthread *curthread, struct pthread *thread)
78{
79	kse_critical_t crit;
80	struct kse *curkse;
81
82	if (thread != NULL) {
83		crit = _kse_critical_enter();
84		curkse = _get_curkse();
85		KSE_LOCK_ACQUIRE(curkse, &_thread_list_lock);
86		thread->refcount--;
87		if (curthread != NULL)
88			curthread->critical_count--;
89		if ((thread->refcount == 0) &&
90		    (thread->tlflags & TLFLAGS_GC_SAFE) != 0)
91			THR_GCLIST_ADD(thread);
92		KSE_LOCK_RELEASE(curkse, &_thread_list_lock);
93		_kse_critical_leave(crit);
94	}
95}
96