linuxthreads/join.c

   1 /* Linuxthreads - a simple clone()-based implementation of Posix        */
   2 /* threads for Linux.                                                   */
   3 /* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr)              */
   4 /*                                                                      */
   5 /* This program is free software; you can redistribute it and/or        */
   6 /* modify it under the terms of the GNU Library General Public License  */
   7 /* as published by the Free Software Foundation; either version 2       */
   8 /* of the License, or (at your option) any later version.               */
   9 /*                                                                      */
  10 /* This program is distributed in the hope that it will be useful,      */
  11 /* but WITHOUT ANY WARRANTY; without even the implied warranty of       */
  12 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        */
  13 /* GNU Library General Public License for more details.                 */
  14
  15 /* Thread termination and joining */
  16
  17 #include <errno.h>
  18 #include <sched.h>
  19 #include <unistd.h>
  20 #include "pthread.h"
  21 #include "internals.h"
  22 #include "spinlock.h"
  23 #include "restart.h"
  24
  25 void pthread_exit(void * retval)
  26 {
  27   pthread_descr self = thread_self();
  28   pthread_descr joining;
  29   struct pthread_request request;
  30
  31   /* Reset the cancellation flag to avoid looping if the cleanup handlers
  32      contain cancellation points */
  33   THREAD_SETMEM(self, p_canceled, 0);
  34   /* Call cleanup functions and destroy the thread-specific data */
  35   __pthread_perform_cleanup();
  36   __pthread_destroy_specifics();
  37   /* Store return value */
  38   __pthread_lock(THREAD_GETMEM(self, p_lock), self);
  39   THREAD_SETMEM(self, p_retval, retval);
  40   /* See whether we have to signal the death.  */
  41   if (THREAD_GETMEM(self, p_report_events))
  42     {
  43       /* See whether TD_DEATH is in any of the mask.  */
  44       int idx = __td_eventword (TD_DEATH);
  45       uint32_t mask = __td_eventmask (TD_DEATH);
  46
  47       if ((mask & (__pthread_threads_events.event_bits[idx]
  48                    | THREAD_GETMEM_NC(self,
  49                                       p_eventbuf.eventmask.event_bits[idx])))
  50           != 0)
  51         {
  52           /* Yep, we have to signal the death.  */
  53           THREAD_SETMEM(self, p_eventbuf.eventnum, TD_DEATH);
  54           THREAD_SETMEM(self, p_eventbuf.eventdata, self);
  55           __pthread_last_event = self;
  56
  57           /* Now call the function to signal the event.  */
  58           __linuxthreads_death_event();
  59         }
  60     }
  61   /* Say that we've terminated */
  62   THREAD_SETMEM(self, p_terminated, 1);
  63   /* See if someone is joining on us */
  64   joining = THREAD_GETMEM(self, p_joining);
  65   __pthread_unlock(THREAD_GETMEM(self, p_lock));
  66   /* Restart joining thread if any */
  67   if (joining != NULL) restart(joining);
  68   /* If this is the initial thread, block until all threads have terminated.
  69      If another thread calls exit, we'll be terminated from our signal
  70      handler. */
  71   if (self == __pthread_main_thread && __pthread_manager_request >= 0) {
  72     request.req_thread = self;
  73     request.req_kind = REQ_MAIN_THREAD_EXIT;
  74     __libc_write(__pthread_manager_request, (char *)&request, sizeof(request));
  75     suspend(self);
  76     /* Main thread flushes stdio streams and runs atexit functions.
  77        It also calls a handler within LinuxThreads which sends a process exit
  78        request to the thread manager. */
  79     exit(0);
  80   }
  81   /* Threads other than the main one  terminate without flushing stdio streams
  82      or running atexit functions. */
  83   _exit(0);
  84 }
  85
  86 /* Function called by pthread_cancel to remove the thread from
  87    waiting on a condition variable queue. */
  88
  89 static int join_extricate_func(void *obj, pthread_descr th)
  90 {
  91   volatile pthread_descr self = thread_self();
  92   pthread_handle handle = obj;
  93   pthread_descr jo;
  94   int did_remove = 0;
  95
  96   __pthread_lock(&handle->h_lock, self);
  97   jo = handle->h_descr;
  98   did_remove = jo->p_joining != NULL;
  99   jo->p_joining = NULL;
 100   __pthread_unlock(&handle->h_lock);
 101
 102   return did_remove;
 103 }
 104
 105 int pthread_join(pthread_t thread_id, void ** thread_return)
 106 {
 107   volatile pthread_descr self = thread_self();
 108   struct pthread_request request;
 109   pthread_handle handle = thread_handle(thread_id);
 110   pthread_descr th;
 111   pthread_extricate_if extr;
 112   int already_canceled = 0;
 113
 114   /* Set up extrication interface */
 115   extr.pu_object = handle;
 116   extr.pu_extricate_func = join_extricate_func;
 117
 118   __pthread_lock(&handle->h_lock, self);
 119   if (invalid_handle(handle, thread_id)) {
 120     __pthread_unlock(&handle->h_lock);
 121     return ESRCH;
 122   }
 123   th = handle->h_descr;
 124   if (th == self) {
 125     __pthread_unlock(&handle->h_lock);
 126     return EDEADLK;
 127   }
 128   /* If detached or already joined, error */
 129   if (th->p_detached || th->p_joining != NULL) {
 130     __pthread_unlock(&handle->h_lock);
 131     return EINVAL;
 132   }
 133   /* If not terminated yet, suspend ourselves. */
 134   if (! th->p_terminated) {
 135     /* Register extrication interface */
 136     __pthread_set_own_extricate_if(self, &extr);
 137     if (!(THREAD_GETMEM(self, p_canceled)
 138         && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE))
 139       th->p_joining = self;
 140     else
 141       already_canceled = 1;
 142     __pthread_unlock(&handle->h_lock);
 143
 144     if (already_canceled) {
 145       __pthread_set_own_extricate_if(self, 0);
 146       pthread_exit(PTHREAD_CANCELED);
 147     }
 148
 149     suspend(self);
 150     /* Deregister extrication interface */
 151     __pthread_set_own_extricate_if(self, 0);
 152
 153     /* This is a cancellation point */
 154     if (THREAD_GETMEM(self, p_woken_by_cancel)
 155         && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
 156       THREAD_SETMEM(self, p_woken_by_cancel, 0);
 157       pthread_exit(PTHREAD_CANCELED);
 158     }
 159     __pthread_lock(&handle->h_lock, self);
 160   }
 161   /* Get return value */
 162   if (thread_return != NULL) *thread_return = th->p_retval;
 163   __pthread_unlock(&handle->h_lock);
 164   /* Send notification to thread manager */
 165   if (__pthread_manager_request >= 0) {
 166     request.req_thread = self;
 167     request.req_kind = REQ_FREE;
 168     request.req_args.free.thread_id = thread_id;
 169     __libc_write(__pthread_manager_request,
 170                  (char *) &request, sizeof(request));
 171   }
 172   return 0;
 173 }
 174
 175 int pthread_detach(pthread_t thread_id)
 176 {
 177   int terminated;
 178   struct pthread_request request;
 179   pthread_handle handle = thread_handle(thread_id);
 180   pthread_descr th;
 181
 182   __pthread_lock(&handle->h_lock, NULL);
 183   if (invalid_handle(handle, thread_id)) {
 184     __pthread_unlock(&handle->h_lock);
 185     return ESRCH;
 186   }
 187   th = handle->h_descr;
 188   /* If already detached, error */
 189   if (th->p_detached) {
 190     __pthread_unlock(&handle->h_lock);
 191     return EINVAL;
 192   }
 193   /* If already joining, don't do anything. */
 194   if (th->p_joining != NULL) {
 195     __pthread_unlock(&handle->h_lock);
 196     return 0;
 197   }
 198   /* Mark as detached */
 199   th->p_detached = 1;
 200   terminated = th->p_terminated;
 201   __pthread_unlock(&handle->h_lock);
 202   /* If already terminated, notify thread manager to reclaim resources */
 203   if (terminated && __pthread_manager_request >= 0) {
 204     request.req_thread = thread_self();
 205     request.req_kind = REQ_FREE;
 206     request.req_args.free.thread_id = thread_id;
 207     __libc_write(__pthread_manager_request,
 208                  (char *) &request, sizeof(request));
 209   }
 210   return 0;
 211 }