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. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  */
  30
  31 #include "namespace.h"
  32 #include <errno.h>
  33 #include <pthread.h>
  34 #include <pthread_np.h>
  35 #include "un-namespace.h"
  36
  37 #include "thr_private.h"
  38
  39 static int suspend_common(struct pthread *, struct pthread *,
  40                 int);
  41
  42 /* Suspend a thread: */
  43 int
  44 _pthread_suspend_np(pthread_t thread)
  45 {
  46         struct pthread *curthread = tls_get_curthread();
  47         int ret;
  48
  49         /* Suspending the current thread doesn't make sense. */
  50         if (thread == curthread)
  51                 ret = EDEADLK;
  52
  53         /* Add a reference to the thread: */
  54         else if ((ret = _thr_ref_add(curthread, thread, /*include dead*/0))
  55             == 0) {
  56                 /* Lock the threads scheduling queue: */
  57                 THR_THREAD_LOCK(curthread, thread);
  58                 suspend_common(curthread, thread, 1);
  59                 /* Unlock the threads scheduling queue: */
  60                 THR_THREAD_UNLOCK(curthread, thread);
  61
  62                 /* Don't forget to remove the reference: */
  63                 _thr_ref_delete(curthread, thread);
  64         }
  65         return (ret);
  66 }
  67
  68 void
  69 _pthread_suspend_all_np(void)
  70 {
  71         struct pthread *curthread = tls_get_curthread();
  72         struct pthread *thread;
  73         int ret;
  74
  75         THREAD_LIST_LOCK(curthread);
  76
  77         TAILQ_FOREACH(thread, &_thread_list, tle) {
  78                 if (thread != curthread) {
  79                         THR_THREAD_LOCK(curthread, thread);
  80                         if (thread->state != PS_DEAD &&
  81                            !(thread->flags & THR_FLAGS_SUSPENDED))
  82                             thread->flags |= THR_FLAGS_NEED_SUSPEND;
  83                         THR_THREAD_UNLOCK(curthread, thread);
  84                 }
  85         }
  86         /* thr_kill(-1, SIGCANCEL); */
  87
  88 restart:
  89         TAILQ_FOREACH(thread, &_thread_list, tle) {
  90                 if (thread != curthread) {
  91                         /* First try to suspend the thread without waiting */
  92                         THR_THREAD_LOCK(curthread, thread);
  93                         ret = suspend_common(curthread, thread, 0);
  94                         if (ret == 0) {
  95                                 /* Can not suspend, try to wait */
  96                                 thread->refcount++;
  97                                 THREAD_LIST_UNLOCK(curthread);
  98                                 suspend_common(curthread, thread, 1);
  99                                 THR_THREAD_UNLOCK(curthread, thread);
 100                                 THREAD_LIST_LOCK(curthread);
 101                                 _thr_ref_delete_unlocked(curthread, thread);
 102                                 /*
 103                                  * Because we were blocked, things may have
 104                                  * been changed, we have to restart the
 105                                  * process.
 106                                  */
 107                                 goto restart;
 108                         }
 109                         THR_THREAD_UNLOCK(curthread, thread);
 110                 }
 111         }
 112
 113         THREAD_LIST_UNLOCK(curthread);
 114 }
 115
 116 static int
 117 suspend_common(struct pthread *curthread, struct pthread *thread,
 118         int waitok)
 119 {
 120         umtx_t tmp;
 121
 122         while (thread->state != PS_DEAD &&
 123               !(thread->flags & THR_FLAGS_SUSPENDED)) {
 124                 thread->flags |= THR_FLAGS_NEED_SUSPEND;
 125                 tmp = thread->cycle;
 126                 _thr_send_sig(thread, SIGCANCEL);
 127                 THR_THREAD_UNLOCK(curthread, thread);
 128                 if (waitok) {
 129                         _thr_umtx_wait(&thread->cycle, tmp, NULL, 0);
 130                         THR_THREAD_LOCK(curthread, thread);
 131                 } else {
 132                         THR_THREAD_LOCK(curthread, thread);
 133                         return (0);
 134                 }
 135         }
 136
 137         return (1);
 138 }
 139
 140 __strong_reference(_pthread_suspend_np, pthread_suspend_np);
 141 __strong_reference(_pthread_suspend_all_np, pthread_suspend_all_np);