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 #include <not-cancel.h>
  26
  27 void __pthread_exit(void * retval)
  28 {
  29   __pthread_do_exit (retval, CURRENT_STACK_FRAME);
  30 }
  31 strong_alias (__pthread_exit, pthread_exit);
  32
  33 void __pthread_do_exit(void *retval, char *currentframe)
  34 {
  35   pthread_descr self = thread_self();
  36   pthread_descr joining;
  37   struct pthread_request request;
  38
  39   /* Reset the cancellation flag to avoid looping if the cleanup handlers
  40      contain cancellation points */
  41   THREAD_SETMEM(self, p_canceled, 0);
  42   /* Call cleanup functions and destroy the thread-specific data */
  43   __pthread_perform_cleanup(currentframe);
  44   __pthread_destroy_specifics();
  45   /* Store return value */
  46   __pthread_lock(THREAD_GETMEM(self, p_lock), self);
  47   THREAD_SETMEM(self, p_retval, retval);
  48   /* See whether we have to signal the death.  */
  49   if (THREAD_GETMEM(self, p_report_events))
  50     {
  51       /* See whether TD_DEATH is in any of the mask.  */
  52       int idx = __td_eventword (TD_DEATH);
  53       uint32_t mask = __td_eventmask (TD_DEATH);
  54
  55       if ((mask & (__pthread_threads_events.event_bits[idx]
  56                    | THREAD_GETMEM_NC(self,
  57                                       p_eventbuf.eventmask.event_bits[idx])))
  58           != 0)
  59         {
  60           /* Yep, we have to signal the death.  */
  61           THREAD_SETMEM(self, p_eventbuf.eventnum, TD_DEATH);
  62           THREAD_SETMEM(self, p_eventbuf.eventdata, self);
  63           __pthread_last_event = self;
  64
  65           /* Now call the function to signal the event.  */
  66           __linuxthreads_death_event();
  67         }
  68     }
  69   /* Say that we've terminated */
  70   THREAD_SETMEM(self, p_terminated, 1);
  71   /* See if someone is joining on us */
  72   joining = THREAD_GETMEM(self, p_joining);
  73   __pthread_unlock(THREAD_GETMEM(self, p_lock));
  74   /* Restart joining thread if any */
  75   if (joining != NULL) restart(joining);
  76   /* If this is the initial thread, block until all threads have terminated.
  77      If another thread calls exit, we'll be terminated from our signal
  78      handler. */
  79   if (self == __pthread_main_thread && __pthread_manager_request >= 0) {
  80     request.req_thread = self;
  81     request.req_kind = REQ_MAIN_THREAD_EXIT;
  82     TEMP_FAILURE_RETRY(write_not_cancel(__pthread_manager_request,
  83                                         (char *)&request, sizeof(request)));
  84     suspend(self);
  85     /* Main thread flushes stdio streams and runs atexit functions.
  86        It also calls a handler within LinuxThreads which sends a process exit
  87        request to the thread manager. */
  88     exit(0);
  89   }
  90   /* Threads other than the main one  terminate without flushing stdio streams
  91      or running atexit functions. */
  92   _exit(0);
  93 }
  94
  95 /* Function called by pthread_cancel to remove the thread from
  96    waiting on a condition variable queue. */
  97
  98 static int join_extricate_func(void *obj, pthread_descr th)
  99 {
 100   volatile pthread_descr self = thread_self();
 101   pthread_handle handle = obj;
 102   pthread_descr jo;
 103   int did_remove = 0;
 104
 105   __pthread_lock(&handle->h_lock, self);
 106   jo = handle->h_descr;
 107   did_remove = jo->p_joining != NULL;
 108   jo->p_joining = NULL;
 109   __pthread_unlock(&handle->h_lock);
 110
 111   return did_remove;
 112 }
 113
 114 int pthread_join(pthread_t thread_id, void ** thread_return)
 115 {
 116   volatile pthread_descr self = thread_self();
 117   struct pthread_request request;
 118   pthread_handle handle = thread_handle(thread_id);
 119   pthread_descr th;
 120   pthread_extricate_if extr;
 121   int already_canceled = 0;
 122
 123   /* Set up extrication interface */
 124   extr.pu_object = handle;
 125   extr.pu_extricate_func = join_extricate_func;
 126
 127   __pthread_lock(&handle->h_lock, self);
 128   if (nonexisting_handle(handle, thread_id)) {
 129     __pthread_unlock(&handle->h_lock);
 130     return ESRCH;
 131   }
 132   th = handle->h_descr;
 133   if (th == self) {
 134     __pthread_unlock(&handle->h_lock);
 135     return EDEADLK;
 136   }
 137   /* If detached or already joined, error */
 138   if (th->p_detached || th->p_joining != NULL) {
 139     __pthread_unlock(&handle->h_lock);
 140     return EINVAL;
 141   }
 142   /* If not terminated yet, suspend ourselves. */
 143   if (! th->p_terminated) {
 144     /* Register extrication interface */
 145     __pthread_set_own_extricate_if(self, &extr);
 146     if (!(THREAD_GETMEM(self, p_canceled)
 147         && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE))
 148       th->p_joining = self;
 149     else
 150       already_canceled = 1;
 151     __pthread_unlock(&handle->h_lock);
 152
 153     if (already_canceled) {
 154       __pthread_set_own_extricate_if(self, 0);
 155       __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME);
 156     }
 157
 158     suspend(self);
 159     /* Deregister extrication interface */
 160     __pthread_set_own_extricate_if(self, 0);
 161
 162     /* This is a cancellation point */
 163     if (THREAD_GETMEM(self, p_woken_by_cancel)
 164         && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
 165       THREAD_SETMEM(self, p_woken_by_cancel, 0);
 166       __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME);
 167     }
 168     __pthread_lock(&handle->h_lock, self);
 169   }
 170   /* Get return value */
 171   if (thread_return != NULL) *thread_return = th->p_retval;
 172   __pthread_unlock(&handle->h_lock);
 173   /* Send notification to thread manager */
 174   if (__pthread_manager_request >= 0) {
 175     request.req_thread = self;
 176     request.req_kind = REQ_FREE;
 177     request.req_args.free.thread_id = thread_id;
 178     TEMP_FAILURE_RETRY(write_not_cancel(__pthread_manager_request,
 179                                         (char *) &request, sizeof(request)));
 180   }
 181   return 0;
 182 }
 183
 184 int pthread_detach(pthread_t thread_id)
 185 {
 186   int terminated;
 187   struct pthread_request request;
 188   pthread_handle handle = thread_handle(thread_id);
 189   pthread_descr th;
 190
 191   __pthread_lock(&handle->h_lock, NULL);
 192   if (nonexisting_handle(handle, thread_id)) {
 193     __pthread_unlock(&handle->h_lock);
 194     return ESRCH;
 195   }
 196   th = handle->h_descr;
 197   /* If already detached, error */
 198   if (th->p_detached) {
 199     __pthread_unlock(&handle->h_lock);
 200     return EINVAL;
 201   }
 202   /* If already joining, don't do anything. */
 203   if (th->p_joining != NULL) {
 204     __pthread_unlock(&handle->h_lock);
 205     return 0;
 206   }
 207   /* Mark as detached */
 208   th->p_detached = 1;
 209   terminated = th->p_terminated;
 210   __pthread_unlock(&handle->h_lock);
 211   /* If already terminated, notify thread manager to reclaim resources */
 212   if (terminated && __pthread_manager_request >= 0) {
 213     request.req_thread = thread_self();
 214     request.req_kind = REQ_FREE;
 215     request.req_args.free.thread_id = thread_id;
 216     TEMP_FAILURE_RETRY(write_not_cancel(__pthread_manager_request,
 217                                         (char *) &request, sizeof(request)));
 218   }
 219   return 0;
 220 }