libpthread/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 #define __FORCE_GLIBC
  18 #include <features.h>
  19 #include <errno.h>
  20 #include "pthread.h"
  21 #include "internals.h"
  22 #include "spinlock.h"
  23 #include "restart.h"
  24 #ifdef __UCLIBC_HAS_RPC__
  25 #include <rpc/rpc.h>
  26 extern void __rpc_thread_destroy(void);
  27 #endif
  28
  29
  30 int pthread_setcancelstate(int state, int * oldstate)
  31 {
  32   pthread_descr self = thread_self();
  33   if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE)
  34     return EINVAL;
  35   if (oldstate != NULL) *oldstate = THREAD_GETMEM(self, p_cancelstate);
  36   THREAD_SETMEM(self, p_cancelstate, state);
  37   if (THREAD_GETMEM(self, p_canceled) &&
  38       THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE &&
  39       THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
  40     pthread_exit(PTHREAD_CANCELED);
  41   return 0;
  42 }
  43
  44 int pthread_setcanceltype(int type, int * oldtype)
  45 {
  46   pthread_descr self = thread_self();
  47   if (type < PTHREAD_CANCEL_DEFERRED || type > PTHREAD_CANCEL_ASYNCHRONOUS)
  48     return EINVAL;
  49   if (oldtype != NULL) *oldtype = THREAD_GETMEM(self, p_canceltype);
  50   THREAD_SETMEM(self, p_canceltype, type);
  51   if (THREAD_GETMEM(self, p_canceled) &&
  52       THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE &&
  53       THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
  54     pthread_exit(PTHREAD_CANCELED);
  55   return 0;
  56 }
  57
  58 int pthread_cancel(pthread_t thread)
  59 {
  60   pthread_handle handle = thread_handle(thread);
  61   int pid;
  62   int dorestart = 0;
  63   pthread_descr th;
  64   pthread_extricate_if *pextricate;
  65
  66   __pthread_lock(&handle->h_lock, NULL);
  67   if (invalid_handle(handle, thread)) {
  68     __pthread_unlock(&handle->h_lock);
  69     return ESRCH;
  70   }
  71
  72   th = handle->h_descr;
  73
  74   if (th->p_canceled) {
  75     __pthread_unlock(&handle->h_lock);
  76     return 0;
  77   }
  78
  79   pextricate = th->p_extricate;
  80   th->p_canceled = 1;
  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_exit(PTHREAD_CANCELED);
 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_exit(PTHREAD_CANCELED);
 162 }
 163
 164 void __pthread_perform_cleanup(void)
 165 {
 166   pthread_descr self = thread_self();
 167   struct _pthread_cleanup_buffer * c;
 168   for (c = THREAD_GETMEM(self, p_cleanup); c != NULL; c = c->__prev)
 169     c->__routine(c->__arg);
 170
 171 #ifdef __UCLIBC_HAS_RPC__
 172   /* And the TSD which needs special help.  */
 173   if (THREAD_GETMEM(self, p_libc_specific[_LIBC_TSD_KEY_RPC_VARS]) != NULL)
 174       __rpc_thread_destroy ();
 175 #endif
 176 }
 177
 178 #ifndef PIC
 179 /* We need a hook to force the cancelation wrappers to be linked in when
 180    static libpthread is used.  */
 181 extern const int __pthread_provide_wrappers;
 182 static const int * const __pthread_require_wrappers =
 183   &__pthread_provide_wrappers;
 184 #endif