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 <rpc/rpc.h>
  19 #include "pthread.h"
  20 #include "internals.h"
  21 #include "spinlock.h"
  22 #include "restart.h"
  23 #include <stackinfo.h>
  24
  25 #include <stdio.h>
  26
  27 int pthread_setcancelstate(int state, int * oldstate)
  28 {
  29   pthread_descr self = thread_self();
  30   if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE)
  31     return EINVAL;
  32   if (oldstate != NULL) *oldstate = THREAD_GETMEM(self, p_cancelstate);
  33   THREAD_SETMEM(self, p_cancelstate, state);
  34   if (THREAD_GETMEM(self, p_canceled) &&
  35       THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE &&
  36       THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
  37     __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME);
  38   return 0;
  39 }
  40
  41 int pthread_setcanceltype(int type, int * oldtype)
  42 {
  43   pthread_descr self = thread_self();
  44   if (type < PTHREAD_CANCEL_DEFERRED || type > PTHREAD_CANCEL_ASYNCHRONOUS)
  45     return EINVAL;
  46   if (oldtype != NULL) *oldtype = THREAD_GETMEM(self, p_canceltype);
  47   THREAD_SETMEM(self, p_canceltype, type);
  48   if (THREAD_GETMEM(self, p_canceled) &&
  49       THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE &&
  50       THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
  51     __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME);
  52   return 0;
  53 }
  54
  55 int pthread_cancel(pthread_t thread)
  56 {
  57   pthread_handle handle = thread_handle(thread);
  58   int pid;
  59   int dorestart = 0;
  60   pthread_descr th;
  61   pthread_extricate_if *pextricate;
  62   int already_canceled;
  63
  64   __pthread_lock(&handle->h_lock, NULL);
  65   if (invalid_handle(handle, thread)) {
  66     __pthread_unlock(&handle->h_lock);
  67     return ESRCH;
  68   }
  69
  70   th = handle->h_descr;
  71
  72   already_canceled = th->p_canceled;
  73   th->p_canceled = 1;
  74
  75   if (th->p_cancelstate == PTHREAD_CANCEL_DISABLE || already_canceled) {
  76     __pthread_unlock(&handle->h_lock);
  77     return 0;
  78   }
  79
  80   pextricate = th->p_extricate;
  81   pid = th->p_pid;
  82
  83   /* If the thread has registered an extrication interface, then
  84      invoke the interface. If it returns 1, then we succeeded in
  85      dequeuing the thread from whatever waiting object it was enqueued
  86      with. In that case, it is our responsibility to wake it up.
  87      And also to set the p_woken_by_cancel flag so the woken thread
  88      can tell that it was woken by cancellation. */
  89
  90   if (pextricate != NULL) {
  91     dorestart = pextricate->pu_extricate_func(pextricate->pu_object, th);
  92     th->p_woken_by_cancel = dorestart;
  93   }
  94
  95   __pthread_unlock(&handle->h_lock);
  96
  97   /* If the thread has suspended or is about to, then we unblock it by
  98      issuing a restart, instead of a cancel signal. Otherwise we send
  99      the cancel signal to unblock the thread from a cancellation point,
 100      or to initiate asynchronous cancellation. The restart is needed so
 101      we have proper accounting of restarts; suspend decrements the thread's
 102      resume count, and restart() increments it.  This also means that suspend's
 103      handling of the cancel signal is obsolete. */
 104
 105   if (dorestart)
 106     restart(th);
 107   else
 108     kill(pid, __pthread_sig_cancel);
 109
 110   return 0;
 111 }
 112
 113 void pthread_testcancel(void)
 114 {
 115   pthread_descr self = thread_self();
 116   if (THREAD_GETMEM(self, p_canceled)
 117       && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE)
 118     __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME);
 119 }
 120
 121 void _pthread_cleanup_push(struct _pthread_cleanup_buffer * buffer,
 122                            void (*routine)(void *), void * arg)
 123 {
 124   pthread_descr self = thread_self();
 125   buffer->__routine = routine;
 126   buffer->__arg = arg;
 127   buffer->__prev = THREAD_GETMEM(self, p_cleanup);
 128   THREAD_SETMEM(self, p_cleanup, buffer);
 129 }
 130
 131 void _pthread_cleanup_pop(struct _pthread_cleanup_buffer * buffer,
 132                           int execute)
 133 {
 134   pthread_descr self = thread_self();
 135   if (execute) buffer->__routine(buffer->__arg);
 136   THREAD_SETMEM(self, p_cleanup, buffer->__prev);
 137 }
 138
 139 void _pthread_cleanup_push_defer(struct _pthread_cleanup_buffer * buffer,
 140                                  void (*routine)(void *), void * arg)
 141 {
 142   pthread_descr self = thread_self();
 143   buffer->__routine = routine;
 144   buffer->__arg = arg;
 145   buffer->__canceltype = THREAD_GETMEM(self, p_canceltype);
 146   buffer->__prev = THREAD_GETMEM(self, p_cleanup);
 147   THREAD_SETMEM(self, p_canceltype, PTHREAD_CANCEL_DEFERRED);
 148   THREAD_SETMEM(self, p_cleanup, buffer);
 149 }
 150
 151 void _pthread_cleanup_pop_restore(struct _pthread_cleanup_buffer * buffer,
 152                                   int execute)
 153 {
 154   pthread_descr self = thread_self();
 155   if (execute) buffer->__routine(buffer->__arg);
 156   THREAD_SETMEM(self, p_cleanup, buffer->__prev);
 157   THREAD_SETMEM(self, p_canceltype, buffer->__canceltype);
 158   if (THREAD_GETMEM(self, p_canceled) &&
 159       THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE &&
 160       THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
 161     __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME);
 162 }
 163
 164 void __pthread_perform_cleanup(char *currentframe)
 165 {
 166   pthread_descr self = thread_self();
 167   struct _pthread_cleanup_buffer * c;
 168
 169   for (c = THREAD_GETMEM(self, p_cleanup); c != NULL; c = c->__prev)
 170     {
 171 #if _STACK_GROWS_DOWN
 172       if ((char *) c <= currentframe)
 173         break;
 174 #elif _STACK_GROWS_UP
 175       if ((char *) c >= currentframe)
 176         break;
 177 #else
 178 # error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
 179 #endif
 180       c->__routine(c->__arg);
 181     }
 182
 183   /* And the TSD which needs special help.  */
 184   if (THREAD_GETMEM(self, p_libc_specific[_LIBC_TSD_KEY_RPC_VARS]) != NULL)
 185     __rpc_thread_destroy ();
 186 }
 187
 188 #ifndef SHARED
 189 /* We need a hook to force the cancelation wrappers to be linked in when
 190    static libpthread is used.  */
 191 extern const int __pthread_provide_wrappers;
 192 static const int * const __pthread_require_wrappers =
 193   &__pthread_provide_wrappers;
 194 #endif