lib/libthr/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  * $FreeBSD$
  30  */
  31
  32 #include "namespace.h"
  33 #include <errno.h>
  34 #include <pthread.h>
  35 #include <pthread_np.h>
  36 #include "un-namespace.h"
  37
  38 #include "thr_private.h"
  39
  40 static int suspend_common(struct pthread *, struct pthread *,
  41                 int);
  42
  43 __weak_reference(_pthread_suspend_np, pthread_suspend_np);
  44 __weak_reference(_pthread_suspend_all_np, pthread_suspend_all_np);
  45
  46 /* Suspend a thread: */
  47 int
  48 _pthread_suspend_np(pthread_t thread)
  49 {
  50         struct pthread *curthread = _get_curthread();
  51         int ret;
  52
  53         /* Suspending the current thread doesn't make sense. */
  54         if (thread == _get_curthread())
  55                 ret = EDEADLK;
  56
  57         /* Add a reference to the thread: */
  58         else if ((ret = _thr_ref_add(curthread, thread, /*include dead*/0))
  59             == 0) {
  60                 /* Lock the threads scheduling queue: */
  61                 THR_THREAD_LOCK(curthread, thread);
  62                 suspend_common(curthread, thread, 1);
  63                 /* Unlock the threads scheduling queue: */
  64                 THR_THREAD_UNLOCK(curthread, thread);
  65
  66                 /* Don't forget to remove the reference: */
  67                 _thr_ref_delete(curthread, thread);
  68         }
  69         return (ret);
  70 }
  71
  72 void
  73 _pthread_suspend_all_np(void)
  74 {
  75         struct pthread *curthread = _get_curthread();
  76         struct pthread *thread;
  77         int ret;
  78
  79         THREAD_LIST_LOCK(curthread);
  80
  81         TAILQ_FOREACH(thread, &_thread_list, tle) {
  82                 if (thread != curthread) {
  83                         THR_THREAD_LOCK(curthread, thread);
  84                         if (thread->state != PS_DEAD &&
  85                            !(thread->flags & THR_FLAGS_SUSPENDED))
  86                             thread->flags |= THR_FLAGS_NEED_SUSPEND;
  87                         THR_THREAD_UNLOCK(curthread, thread);
  88                 }
  89         }
  90         thr_kill(-1, SIGCANCEL);
  91
  92 restart:
  93         TAILQ_FOREACH(thread, &_thread_list, tle) {
  94                 if (thread != curthread) {
  95                         /* First try to suspend the thread without waiting */
  96                         THR_THREAD_LOCK(curthread, thread);
  97                         ret = suspend_common(curthread, thread, 0);
  98                         if (ret == 0) {
  99                                 /* Can not suspend, try to wait */
 100                                 thread->refcount++;
 101                                 THREAD_LIST_UNLOCK(curthread);
 102                                 suspend_common(curthread, thread, 1);
 103                                 THR_THREAD_UNLOCK(curthread, thread);
 104                                 THREAD_LIST_LOCK(curthread);
 105                                 _thr_ref_delete_unlocked(curthread, thread);
 106                                 /*
 107                                  * Because we were blocked, things may have
 108                                  * been changed, we have to restart the
 109                                  * process.
 110                                  */
 111                                 goto restart;
 112                         }
 113                         THR_THREAD_UNLOCK(curthread, thread);
 114                 }
 115         }
 116
 117         THREAD_LIST_UNLOCK(curthread);
 118 }
 119
 120 static int
 121 suspend_common(struct pthread *curthread, struct pthread *thread,
 122         int waitok)
 123 {
 124         long tmp;
 125
 126         while (thread->state != PS_DEAD &&
 127               !(thread->flags & THR_FLAGS_SUSPENDED)) {
 128                 thread->flags |= THR_FLAGS_NEED_SUSPEND;
 129                 tmp = thread->cycle;
 130                 THR_THREAD_UNLOCK(curthread, thread);
 131                 _thr_send_sig(thread, SIGCANCEL);
 132                 if (waitok) {
 133                         _thr_umtx_wait_uint(&thread->cycle, tmp, NULL, 0);
 134                         THR_THREAD_LOCK(curthread, thread);
 135                 } else {
 136                         THR_THREAD_LOCK(curthread, thread);
 137                         return (0);
 138                 }
 139         }
 140
 141         return (1);
 142 }