linuxthreads/cancel.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 cancellation */
  16
  17 #include <errno.h>
  18 #include "pthread.h"
  19 #include "internals.h"
  20 #include "spinlock.h"
  21 #include "restart.h"
  22
  23 int pthread_setcancelstate(int state, int * oldstate)
  24 {
  25   pthread_descr self = thread_self();
  26   if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE)
  27     return EINVAL;
  28   if (oldstate != NULL) *oldstate = THREAD_GETMEM(self, p_cancelstate);
  29   THREAD_SETMEM(self, p_cancelstate, state);
  30   if (THREAD_GETMEM(self, p_canceled) &&
  31       THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE &&
  32       THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
  33     pthread_exit(PTHREAD_CANCELED);
  34   return 0;
  35 }
  36
  37 int pthread_setcanceltype(int type, int * oldtype)
  38 {
  39   pthread_descr self = thread_self();
  40   if (type < PTHREAD_CANCEL_DEFERRED || type > PTHREAD_CANCEL_ASYNCHRONOUS)
  41     return EINVAL;
  42   if (oldtype != NULL) *oldtype = THREAD_GETMEM(self, p_canceltype);
  43   THREAD_SETMEM(self, p_canceltype, type);
  44   if (THREAD_GETMEM(self, p_canceled) &&
  45       THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE &&
  46       THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
  47     pthread_exit(PTHREAD_CANCELED);
  48   return 0;
  49 }
  50
  51 int pthread_cancel(pthread_t thread)
  52 {
  53   pthread_handle handle = thread_handle(thread);
  54   int pid;
  55   int dorestart = 0;
  56   pthread_descr th;
  57   pthread_extricate_if *pextricate;
  58
  59   __pthread_lock(&handle->h_lock, NULL);
  60   if (invalid_handle(handle, thread)) {
  61     __pthread_unlock(&handle->h_lock);
  62     return ESRCH;
  63   }
  64
  65   th = handle->h_descr;
  66
  67   if (th->p_canceled) {
  68     __pthread_unlock(&handle->h_lock);
  69     return 0;
  70   }
  71
  72   pextricate = th->p_extricate;
  73   th->p_canceled = 1;
  74   pid = th->p_pid;
  75
  76   /* If the thread has registered an extrication interface, then
  77      invoke the interface. If it returns 1, then we succeeded in
  78      dequeuing the thread from whatever waiting object it was enqueued
  79      with. In that case, it is our responsibility to wake it up.
  80      And also to set the p_woken_by_cancel flag so the woken thread
  81      can tell that it was woken by cancellation. */
  82
  83   if (pextricate != NULL) {
  84     dorestart = pextricate->pu_extricate_func(pextricate->pu_object, th);
  85     th->p_woken_by_cancel = dorestart;
  86   }
  87
  88   __pthread_unlock(&handle->h_lock);
  89
  90   /* If the thread has suspended or is about to, then we unblock it by
  91      issuing a restart, instead of a cancel signal. Otherwise we send
  92      the cancel signal to unblock the thread from a cancellation point,
  93      or to initiate asynchronous cancellation. The restart is needed so
  94      we have proper accounting of restarts; suspend decrements the thread's
  95      resume count, and restart() increments it.  This also means that suspend's
  96      handling of the cancel signal is obsolete. */
  97
  98   if (dorestart)
  99     restart(th);
 100   else
 101     kill(pid, __pthread_sig_cancel);
 102
 103   return 0;
 104 }
 105
 106 void pthread_testcancel(void)
 107 {
 108   pthread_descr self = thread_self();
 109   if (THREAD_GETMEM(self, p_canceled)
 110       && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE)
 111     pthread_exit(PTHREAD_CANCELED);
 112 }
 113
 114 void _pthread_cleanup_push(struct _pthread_cleanup_buffer * buffer,
 115                            void (*routine)(void *), void * arg)
 116 {
 117   pthread_descr self = thread_self();
 118   buffer->__routine = routine;
 119   buffer->__arg = arg;
 120   buffer->__prev = THREAD_GETMEM(self, p_cleanup);
 121   THREAD_SETMEM(self, p_cleanup, buffer);
 122 }
 123
 124 void _pthread_cleanup_pop(struct _pthread_cleanup_buffer * buffer,
 125                           int execute)
 126 {
 127   pthread_descr self = thread_self();
 128   if (execute) buffer->__routine(buffer->__arg);
 129   THREAD_SETMEM(self, p_cleanup, buffer->__prev);
 130 }
 131
 132 void _pthread_cleanup_push_defer(struct _pthread_cleanup_buffer * buffer,
 133                                  void (*routine)(void *), void * arg)
 134 {
 135   pthread_descr self = thread_self();
 136   buffer->__routine = routine;
 137   buffer->__arg = arg;
 138   buffer->__canceltype = THREAD_GETMEM(self, p_canceltype);
 139   buffer->__prev = THREAD_GETMEM(self, p_cleanup);
 140   THREAD_SETMEM(self, p_canceltype, PTHREAD_CANCEL_DEFERRED);
 141   THREAD_SETMEM(self, p_cleanup, buffer);
 142 }
 143
 144 void _pthread_cleanup_pop_restore(struct _pthread_cleanup_buffer * buffer,
 145                                   int execute)
 146 {
 147   pthread_descr self = thread_self();
 148   if (execute) buffer->__routine(buffer->__arg);
 149   THREAD_SETMEM(self, p_cleanup, buffer->__prev);
 150   THREAD_SETMEM(self, p_canceltype, buffer->__canceltype);
 151   if (THREAD_GETMEM(self, p_canceled) &&
 152       THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE &&
 153       THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
 154     pthread_exit(PTHREAD_CANCELED);
 155 }
 156
 157 void __pthread_perform_cleanup(void)
 158 {
 159   pthread_descr self = thread_self();
 160   struct _pthread_cleanup_buffer * c;
 161   for (c = THREAD_GETMEM(self, p_cleanup); c != NULL; c = c->__prev)
 162     c->__routine(c->__arg);
 163 }
 164
 165 #ifndef SHARED
 166 /* We need a hook to force the cancelation wrappers to be linked in when
 167    static libpthread is used.  */
 168 extern const int __pthread_provide_wrappers;
 169 static const int * const __pthread_require_wrappers =
 170   &__pthread_provide_wrappers;
 171 #endif