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 <stdlib.h>
  20 #include <unistd.h>
  21 #include "pthread.h"
  22 #include "internals.h"
  23 #include "spinlock.h"
  24 #include "restart.h"
  25
  26 void pthread_exit(void * retval)
  27 {
  28   __pthread_do_exit (retval, CURRENT_STACK_FRAME);
  29 }
  30
  31 void __pthread_do_exit(void *retval, char *currentframe)
  32 {
  33   pthread_descr self = thread_self();
  34   pthread_descr joining;
  35   struct pthread_request request;
  36
  37   /* Reset the cancellation flag to avoid looping if the cleanup handlers
  38      contain cancellation points */
  39   THREAD_SETMEM(self, p_canceled, 0);
  40   /* Call cleanup functions and destroy the thread-specific data */
  41   __pthread_perform_cleanup(currentframe);
  42   __pthread_destroy_specifics();
  43   /* Store return value */
  44   __pthread_lock(THREAD_GETMEM(self, p_lock), self);
  45   THREAD_SETMEM(self, p_retval, retval);
  46   /* See whether we have to signal the death.  */
  47   if (THREAD_GETMEM(self, p_report_events))
  48     {
  49       /* See whether TD_DEATH is in any of the mask.  */
  50       int idx = __td_eventword (TD_DEATH);
  51       uint32_t mask = __td_eventmask (TD_DEATH);
  52
  53       if ((mask & (__pthread_threads_events.event_bits[idx]
  54                    | THREAD_GETMEM_NC(self,
  55                                       p_eventbuf.eventmask.event_bits[idx])))
  56           != 0)
  57         {
  58           /* Yep, we have to signal the death.  */
  59           THREAD_SETMEM(self, p_eventbuf.eventnum, TD_DEATH);
  60           THREAD_SETMEM(self, p_eventbuf.eventdata, self);
  61           __pthread_last_event = self;
  62
  63           /* Now call the function to signal the event.  */
  64           __linuxthreads_death_event();
  65         }
  66     }
  67   /* Say that we've terminated */
  68   THREAD_SETMEM(self, p_terminated, 1);
  69   /* See if someone is joining on us */
  70   joining = THREAD_GETMEM(self, p_joining);
  71   __pthread_unlock(THREAD_GETMEM(self, p_lock));
  72   /* Restart joining thread if any */
  73   if (joining != NULL) restart(joining);
  74   /* If this is the initial thread, block until all threads have terminated.
  75      If another thread calls exit, we'll be terminated from our signal
  76      handler. */
  77   if (self == __pthread_main_thread && __pthread_manager_request >= 0) {
  78     request.req_thread = self;
  79     request.req_kind = REQ_MAIN_THREAD_EXIT;
  80     __libc_write(__pthread_manager_request, (char *)&request, sizeof(request));
  81     suspend(self);
  82     /* Main thread flushes stdio streams and runs atexit functions.
  83        It also calls a handler within LinuxThreads which sends a process exit
  84        request to the thread manager. */
  85     exit(0);
  86   }
  87   /* Threads other than the main one  terminate without flushing stdio streams
  88      or running atexit functions. */
  89   _exit(0);
  90 }
  91
  92 /* Function called by pthread_cancel to remove the thread from
  93    waiting on a condition variable queue. */
  94
  95 static int join_extricate_func(void *obj, pthread_descr th)
  96 {
  97   volatile pthread_descr self = thread_self();
  98   pthread_handle handle = obj;
  99   pthread_descr jo;
 100   int did_remove = 0;
 101
 102   __pthread_lock(&handle->h_lock, self);
 103   jo = handle->h_descr;
 104   did_remove = jo->p_joining != NULL;
 105   jo->p_joining = NULL;
 106   __pthread_unlock(&handle->h_lock);
 107
 108   return did_remove;
 109 }
 110
 111 int pthread_join(pthread_t thread_id, void ** thread_return)
 112 {
 113   volatile pthread_descr self = thread_self();
 114   struct pthread_request request;
 115   pthread_handle handle = thread_handle(thread_id);
 116   pthread_descr th;
 117   pthread_extricate_if extr;
 118   int already_canceled = 0;
 119
 120   /* Set up extrication interface */
 121   extr.pu_object = handle;
 122   extr.pu_extricate_func = join_extricate_func;
 123
 124   __pthread_lock(&handle->h_lock, self);
 125   if (nonexisting_handle(handle, thread_id)) {
 126     __pthread_unlock(&handle->h_lock);
 127     return ESRCH;
 128   }
 129   th = handle->h_descr;
 130   if (th == self) {
 131     __pthread_unlock(&handle->h_lock);
 132     return EDEADLK;
 133   }
 134   /* If detached or already joined, error */
 135   if (th->p_detached || th->p_joining != NULL) {
 136     __pthread_unlock(&handle->h_lock);
 137     return EINVAL;
 138   }
 139   /* If not terminated yet, suspend ourselves. */
 140   if (! th->p_terminated) {
 141     /* Register extrication interface */
 142     __pthread_set_own_extricate_if(self, &extr);
 143     if (!(THREAD_GETMEM(self, p_canceled)
 144         && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE))
 145       th->p_joining = self;
 146     else
 147       already_canceled = 1;
 148     __pthread_unlock(&handle->h_lock);
 149
 150     if (already_canceled) {
 151       __pthread_set_own_extricate_if(self, 0);
 152       __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME);
 153     }
 154
 155     suspend(self);
 156     /* Deregister extrication interface */
 157     __pthread_set_own_extricate_if(self, 0);
 158
 159     /* This is a cancellation point */
 160     if (THREAD_GETMEM(self, p_woken_by_cancel)
 161         && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
 162       THREAD_SETMEM(self, p_woken_by_cancel, 0);
 163       __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME);
 164     }
 165     __pthread_lock(&handle->h_lock, self);
 166   }
 167   /* Get return value */
 168   if (thread_return != NULL) *thread_return = th->p_retval;
 169   __pthread_unlock(&handle->h_lock);
 170   /* Send notification to thread manager */
 171   if (__pthread_manager_request >= 0) {
 172     request.req_thread = self;
 173     request.req_kind = REQ_FREE;
 174     request.req_args.free.thread_id = thread_id;
 175     __libc_write(__pthread_manager_request,
 176                  (char *) &request, sizeof(request));
 177   }
 178   return 0;
 179 }
 180
 181 int pthread_detach(pthread_t thread_id)
 182 {
 183   int terminated;
 184   struct pthread_request request;
 185   pthread_handle handle = thread_handle(thread_id);
 186   pthread_descr th;
 187
 188   __pthread_lock(&handle->h_lock, NULL);
 189   if (nonexisting_handle(handle, thread_id)) {
 190     __pthread_unlock(&handle->h_lock);
 191     return ESRCH;
 192   }
 193   th = handle->h_descr;
 194   /* If already detached, error */
 195   if (th->p_detached) {
 196     __pthread_unlock(&handle->h_lock);
 197     return EINVAL;
 198   }
 199   /* If already joining, don't do anything. */
 200   if (th->p_joining != NULL) {
 201     __pthread_unlock(&handle->h_lock);
 202     return 0;
 203   }
 204   /* Mark as detached */
 205   th->p_detached = 1;
 206   terminated = th->p_terminated;
 207   __pthread_unlock(&handle->h_lock);
 208   /* If already terminated, notify thread manager to reclaim resources */
 209   if (terminated && __pthread_manager_request >= 0) {
 210     request.req_thread = thread_self();
 211     request.req_kind = REQ_FREE;
 212     request.req_args.free.thread_id = thread_id;
 213     __libc_write(__pthread_manager_request,
 214                  (char *) &request, sizeof(request));
 215   }
 216   return 0;
 217 }