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   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   acquire(self->p_spinlock);
  39   self->p_retval = retval;
  40   /* Say that we've terminated */
  41   self->p_terminated = 1;
  42   /* See if someone is joining on us */
  43   joining = self->p_joining;
  44   release(self->p_spinlock);
  45   /* Restart joining thread if any */
  46   if (joining != NULL) restart(joining);
  47   /* If this is the initial thread, block until all threads have terminated.
  48      If another thread calls exit, we'll be terminated from our signal
  49      handler. */
  50   if (self == __pthread_main_thread && __pthread_manager_request >= 0) {
  51     request.req_thread = self;
  52     request.req_kind = REQ_MAIN_THREAD_EXIT;
  53     __libc_write(__pthread_manager_request, (char *)&request, sizeof(request));
  54     suspend(self);
  55   }
  56   /* Exit the process (but don't flush stdio streams, and don't run
  57      atexit functions). */
  58   _exit(0);
  59 }
  60
  61 int pthread_join(pthread_t thread_id, void ** thread_return)
  62 {
  63   volatile pthread_descr self = thread_self();
  64   struct pthread_request request;
  65   pthread_handle handle = thread_handle(thread_id);
  66   pthread_descr th;
  67
  68   acquire(&handle->h_spinlock);
  69   if (invalid_handle(handle, thread_id)) {
  70     release(&handle->h_spinlock);
  71     return ESRCH;
  72   }
  73   th = handle->h_descr;
  74   if (th == self) {
  75     release(&handle->h_spinlock);
  76     return EDEADLK;
  77   }
  78   /* If detached or already joined, error */
  79   if (th->p_detached || th->p_joining != NULL) {
  80     release(&handle->h_spinlock);
  81     return EINVAL;
  82   }
  83   /* If not terminated yet, suspend ourselves. */
  84   if (! th->p_terminated) {
  85     th->p_joining = self;
  86     release(&handle->h_spinlock);
  87     suspend_with_cancellation(self);
  88     /* This is a cancellation point */
  89     if (self->p_canceled && self->p_cancelstate == PTHREAD_CANCEL_ENABLE) {
  90       th->p_joining = NULL;
  91       pthread_exit(PTHREAD_CANCELED);
  92     }
  93     acquire(&handle->h_spinlock);
  94   }
  95   /* Get return value */
  96   if (thread_return != NULL) *thread_return = th->p_retval;
  97   release(&handle->h_spinlock);
  98   /* Send notification to thread manager */
  99   if (__pthread_manager_request >= 0) {
 100     request.req_thread = self;
 101     request.req_kind = REQ_FREE;
 102     request.req_args.free.thread = th;
 103     __libc_write(__pthread_manager_request,
 104                  (char *) &request, sizeof(request));
 105   }
 106   return 0;
 107 }
 108
 109 int pthread_detach(pthread_t thread_id)
 110 {
 111   int terminated;
 112   struct pthread_request request;
 113   pthread_handle handle = thread_handle(thread_id);
 114   pthread_descr th;
 115
 116   acquire(&handle->h_spinlock);
 117   if (invalid_handle(handle, thread_id)) {
 118     release(&handle->h_spinlock);
 119     return ESRCH;
 120   }
 121   th = handle->h_descr;
 122   /* If already detached, error */
 123   if (th->p_detached) {
 124     release(&handle->h_spinlock);
 125     return EINVAL;
 126   }
 127   /* If already joining, don't do anything. */
 128   if (th->p_joining != NULL) {
 129     release(&handle->h_spinlock);
 130     return 0;
 131   }
 132   /* Mark as detached */
 133   th->p_detached = 1;
 134   terminated = th->p_terminated;
 135   release(&handle->h_spinlock);
 136   /* If already terminated, notify thread manager to reclaim resources */
 137   if (terminated && __pthread_manager_request >= 0) {
 138     request.req_thread = thread_self();
 139     request.req_kind = REQ_FREE;
 140     request.req_args.free.thread = th;
 141     __libc_write(__pthread_manager_request,
 142                  (char *) &request, sizeof(request));
 143   }
 144   return 0;
 145 }