lib/libthread_xu/thread/thr_suspend_np.c

   1 /*
   2  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by John Birrell.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/lib/libpthread/thread/thr_suspend_np.c,v 1.19 2003/05/04 16:17:01 deischen Exp $
  33  * $DragonFly: src/lib/libthread_xu/thread/thr_suspend_np.c,v 1.3 2006/03/19 13:07:12 davidxu Exp $
  34  */
  35
  36 #include <errno.h>
  37 #include <pthread.h>
  38
  39 #include "thr_private.h"
  40
  41 static int suspend_common(struct pthread *, struct pthread *,
  42                 int);
  43
  44 __weak_reference(_pthread_suspend_np, pthread_suspend_np);
  45 __weak_reference(_pthread_suspend_all_np, pthread_suspend_all_np);
  46
  47 /* Suspend a thread: */
  48 int
  49 _pthread_suspend_np(pthread_t thread)
  50 {
  51         struct pthread *curthread = tls_get_curthread();
  52         int ret;
  53
  54         /* Suspending the current thread doesn't make sense. */
  55         if (thread == curthread)
  56                 ret = EDEADLK;
  57
  58         /* Add a reference to the thread: */
  59         else if ((ret = _thr_ref_add(curthread, thread, /*include dead*/0))
  60             == 0) {
  61                 /* Lock the threads scheduling queue: */
  62                 THR_THREAD_LOCK(curthread, thread);
  63                 suspend_common(curthread, thread, 1);
  64                 /* Unlock the threads scheduling queue: */
  65                 THR_THREAD_UNLOCK(curthread, thread);
  66
  67                 /* Don't forget to remove the reference: */
  68                 _thr_ref_delete(curthread, thread);
  69         }
  70         return (ret);
  71 }
  72
  73 void
  74 _pthread_suspend_all_np(void)
  75 {
  76         struct pthread *curthread = tls_get_curthread();
  77         struct pthread *thread;
  78         int ret;
  79
  80         THREAD_LIST_LOCK(curthread);
  81
  82         TAILQ_FOREACH(thread, &_thread_list, tle) {
  83                 if (thread != curthread) {
  84                         THR_THREAD_LOCK(curthread, thread);
  85                         if (thread->state != PS_DEAD &&
  86                            !(thread->flags & THR_FLAGS_SUSPENDED))
  87                             thread->flags |= THR_FLAGS_NEED_SUSPEND;
  88                         THR_THREAD_UNLOCK(curthread, thread);
  89                 }
  90         }
  91         /* thr_kill(-1, SIGCANCEL); */
  92
  93 restart:
  94         TAILQ_FOREACH(thread, &_thread_list, tle) {
  95                 if (thread != curthread) {
  96                         /* First try to suspend the thread without waiting */
  97                         THR_THREAD_LOCK(curthread, thread);
  98                         ret = suspend_common(curthread, thread, 0);
  99                         if (ret == 0) {
 100                                 /* Can not suspend, try to wait */
 101                                 thread->refcount++;
 102                                 THREAD_LIST_UNLOCK(curthread);
 103                                 suspend_common(curthread, thread, 1);
 104                                 THR_THREAD_UNLOCK(curthread, thread);
 105                                 THREAD_LIST_LOCK(curthread);
 106                                 _thr_ref_delete_unlocked(curthread, thread);
 107                                 /*
 108                                  * Because we were blocked, things may have
 109                                  * been changed, we have to restart the
 110                                  * process.
 111                                  */
 112                                 goto restart;
 113                         }
 114                         THR_THREAD_UNLOCK(curthread, thread);
 115                 }
 116         }
 117
 118         THREAD_LIST_UNLOCK(curthread);
 119 }
 120
 121 static int
 122 suspend_common(struct pthread *curthread, struct pthread *thread,
 123         int waitok)
 124 {
 125         umtx_t tmp;
 126
 127         while (thread->state != PS_DEAD &&
 128               !(thread->flags & THR_FLAGS_SUSPENDED)) {
 129                 thread->flags |= THR_FLAGS_NEED_SUSPEND;
 130                 tmp = thread->cycle;
 131                 THR_THREAD_UNLOCK(curthread, thread);
 132                 _thr_send_sig(thread, SIGCANCEL);
 133                 if (waitok) {
 134                         _thr_umtx_wait(&thread->cycle, tmp, NULL, 0);
 135                         THR_THREAD_LOCK(curthread, thread);
 136                 } else {
 137                         THR_THREAD_LOCK(curthread, thread);
 138                         return (0);
 139                 }
 140         }
 141
 142         return (1);
 143 }