lib/libthr/thread/thr_suspend_np.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the author nor the names of any co-contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #include "namespace.h"
  34 #include <errno.h>
  35 #include <pthread.h>
  36 #include <pthread_np.h>
  37 #include "un-namespace.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 = _get_curthread();
  52         int ret;
  53
  54         /* Suspending the current thread doesn't make sense. */
  55         if (thread == _get_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 _thr_suspend_all_lock(struct pthread *curthread)
  75 {
  76         int old;
  77
  78         THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
  79         while (_single_thread != NULL) {
  80                 old = _suspend_all_cycle;
  81                 _suspend_all_waiters++;
  82                 THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
  83                 _thr_umtx_wait_uint(&_suspend_all_cycle, old, NULL, 0);
  84                 THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
  85                 _suspend_all_waiters--;
  86         }
  87         _single_thread = curthread;
  88         THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
  89 }
  90
  91 void
  92 _thr_suspend_all_unlock(struct pthread *curthread)
  93 {
  94
  95         THR_LOCK_ACQUIRE(curthread, &_suspend_all_lock);
  96         _single_thread = NULL;
  97         if (_suspend_all_waiters != 0) {
  98                 _suspend_all_cycle++;
  99                 _thr_umtx_wake(&_suspend_all_cycle, INT_MAX, 0);
 100         }
 101         THR_LOCK_RELEASE(curthread, &_suspend_all_lock);
 102 }
 103
 104 void
 105 _pthread_suspend_all_np(void)
 106 {
 107         struct pthread *curthread = _get_curthread();
 108         struct pthread *thread;
 109         int old_nocancel;
 110         int ret;
 111
 112         old_nocancel = curthread->no_cancel;
 113         curthread->no_cancel = 1;
 114         _thr_suspend_all_lock(curthread);
 115         THREAD_LIST_RDLOCK(curthread);
 116         TAILQ_FOREACH(thread, &_thread_list, tle) {
 117                 if (thread != curthread) {
 118                         THR_THREAD_LOCK(curthread, thread);
 119                         if (thread->state != PS_DEAD &&
 120                            !(thread->flags & THR_FLAGS_SUSPENDED))
 121                             thread->flags |= THR_FLAGS_NEED_SUSPEND;
 122                         THR_THREAD_UNLOCK(curthread, thread);
 123                 }
 124         }
 125         thr_kill(-1, SIGCANCEL);
 126
 127 restart:
 128         TAILQ_FOREACH(thread, &_thread_list, tle) {
 129                 if (thread != curthread) {
 130                         /* First try to suspend the thread without waiting */
 131                         THR_THREAD_LOCK(curthread, thread);
 132                         ret = suspend_common(curthread, thread, 0);
 133                         if (ret == 0) {
 134                                 THREAD_LIST_UNLOCK(curthread);
 135                                 /* Can not suspend, try to wait */
 136                                 THR_REF_ADD(curthread, thread);
 137                                 suspend_common(curthread, thread, 1);
 138                                 THR_REF_DEL(curthread, thread);
 139                                 _thr_try_gc(curthread, thread);
 140                                 /* thread lock released */
 141
 142                                 THREAD_LIST_RDLOCK(curthread);
 143                                 /*
 144                                  * Because we were blocked, things may have
 145                                  * been changed, we have to restart the
 146                                  * process.
 147                                  */
 148                                 goto restart;
 149                         }
 150                         THR_THREAD_UNLOCK(curthread, thread);
 151                 }
 152         }
 153         THREAD_LIST_UNLOCK(curthread);
 154         _thr_suspend_all_unlock(curthread);
 155         curthread->no_cancel = old_nocancel;
 156         _thr_testcancel(curthread);
 157 }
 158
 159 static int
 160 suspend_common(struct pthread *curthread, struct pthread *thread,
 161         int waitok)
 162 {
 163         uint32_t tmp;
 164
 165         while (thread->state != PS_DEAD &&
 166               !(thread->flags & THR_FLAGS_SUSPENDED)) {
 167                 thread->flags |= THR_FLAGS_NEED_SUSPEND;
 168                 /* Thread is in creation. */
 169                 if (thread->tid == TID_TERMINATED)
 170                         return (1);
 171                 tmp = thread->cycle;
 172                 _thr_send_sig(thread, SIGCANCEL);
 173                 THR_THREAD_UNLOCK(curthread, thread);
 174                 if (waitok) {
 175                         _thr_umtx_wait_uint(&thread->cycle, tmp, NULL, 0);
 176                         THR_THREAD_LOCK(curthread, thread);
 177                 } else {
 178                         THR_THREAD_LOCK(curthread, thread);
 179                         return (0);
 180                 }
 181         }
 182
 183         return (1);
 184 }