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   /* Say that we've terminated */
  41   THREAD_SETMEM(self, p_terminated, 1);
  42   /* See whether we have to signal the death.  */
  43   if (THREAD_GETMEM(self, p_report_events))
  44     {
  45       /* See whether TD_DEATH is in any of the mask.  */
  46       int idx = __td_eventword (TD_DEATH);
  47       uint32_t mask = __td_eventmask (TD_DEATH);
  48
  49       if ((mask & (__pthread_threads_events.event_bits[idx]
  50                    | THREAD_GETMEM(self,
  51                                    p_eventbuf.eventmask).event_bits[idx]))
  52           != 0)
  53         {
  54           /* Yep, we have to signal the death.  */
  55           THREAD_SETMEM(self, p_eventbuf.eventnum, TD_DEATH);
  56           THREAD_SETMEM(self, p_eventbuf.eventdata, self);
  57           __pthread_last_event = self;
  58
  59           /* Now call the function to signal the event.  */
  60           __linuxthreads_death_event();
  61         }
  62     }
  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   }
  77   /* Exit the process (but don't flush stdio streams, and don't run
  78      atexit functions). */
  79   _exit(0);
  80 }
  81
  82 int pthread_join(pthread_t thread_id, void ** thread_return)
  83 {
  84   volatile pthread_descr self = thread_self();
  85   struct pthread_request request;
  86   pthread_handle handle = thread_handle(thread_id);
  87   pthread_descr th;
  88
  89   __pthread_lock(&handle->h_lock, self);
  90   if (invalid_handle(handle, thread_id)) {
  91     __pthread_unlock(&handle->h_lock);
  92     return ESRCH;
  93   }
  94   th = handle->h_descr;
  95   if (th == self) {
  96     __pthread_unlock(&handle->h_lock);
  97     return EDEADLK;
  98   }
  99   /* If detached or already joined, error */
 100   if (th->p_detached || th->p_joining != NULL) {
 101     __pthread_unlock(&handle->h_lock);
 102     return EINVAL;
 103   }
 104   /* If not terminated yet, suspend ourselves. */
 105   if (! th->p_terminated) {
 106     th->p_joining = self;
 107     __pthread_unlock(&handle->h_lock);
 108     suspend_with_cancellation(self);
 109     /* This is a cancellation point */
 110     if (THREAD_GETMEM(self, p_canceled)
 111         && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
 112       th->p_joining = NULL;
 113       pthread_exit(PTHREAD_CANCELED);
 114     }
 115     __pthread_lock(&handle->h_lock, self);
 116   }
 117   /* Get return value */
 118   if (thread_return != NULL) *thread_return = th->p_retval;
 119   __pthread_unlock(&handle->h_lock);
 120   /* Send notification to thread manager */
 121   if (__pthread_manager_request >= 0) {
 122     request.req_thread = self;
 123     request.req_kind = REQ_FREE;
 124     request.req_args.free.thread_id = thread_id;
 125     __libc_write(__pthread_manager_request,
 126                  (char *) &request, sizeof(request));
 127   }
 128   return 0;
 129 }
 130
 131 int pthread_detach(pthread_t thread_id)
 132 {
 133   int terminated;
 134   struct pthread_request request;
 135   pthread_handle handle = thread_handle(thread_id);
 136   pthread_descr th;
 137
 138   __pthread_lock(&handle->h_lock, NULL);
 139   if (invalid_handle(handle, thread_id)) {
 140     __pthread_unlock(&handle->h_lock);
 141     return ESRCH;
 142   }
 143   th = handle->h_descr;
 144   /* If already detached, error */
 145   if (th->p_detached) {
 146     __pthread_unlock(&handle->h_lock);
 147     return EINVAL;
 148   }
 149   /* If already joining, don't do anything. */
 150   if (th->p_joining != NULL) {
 151     __pthread_unlock(&handle->h_lock);
 152     return 0;
 153   }
 154   /* Mark as detached */
 155   th->p_detached = 1;
 156   terminated = th->p_terminated;
 157   __pthread_unlock(&handle->h_lock);
 158   /* If already terminated, notify thread manager to reclaim resources */
 159   if (terminated && __pthread_manager_request >= 0) {
 160     request.req_thread = thread_self();
 161     request.req_kind = REQ_FREE;
 162     request.req_args.free.thread_id = thread_id;
 163     __libc_write(__pthread_manager_request,
 164                  (char *) &request, sizeof(request));
 165   }
 166   return 0;
 167 }