lib/libc_r/uthread/uthread_cancel.c

   1 /*
   2  * David Leonard <d@openbsd.org>, 1999. Public domain.
   3  * $FreeBSD: src/lib/libc_r/uthread/uthread_cancel.c,v 1.3.2.9 2002/10/22 14:44:02 fjoe Exp $
   4  * $DragonFly: src/lib/libc_r/uthread/uthread_cancel.c,v 1.4 2005/05/30 20:50:53 joerg Exp $
   5  */
   6 #include <sys/errno.h>
   7 #include <pthread.h>
   8 #include "pthread_private.h"
   9
  10 static void     finish_cancellation(void *arg);
  11
  12 int
  13 _pthread_cancel(pthread_t pthread)
  14 {
  15         int ret;
  16
  17         if ((ret = _find_thread(pthread)) != 0) {
  18                 /* NOTHING */
  19         } else if (pthread->state == PS_DEAD || pthread->state == PS_DEADLOCK
  20             || (pthread->flags & PTHREAD_EXITING) != 0) {
  21                 ret = 0;
  22         } else {
  23                 /* Protect the scheduling queues: */
  24                 _thread_kern_sig_defer();
  25
  26                 if (((pthread->cancelflags & PTHREAD_CANCEL_DISABLE) != 0) ||
  27                     (((pthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) == 0) &&
  28                     ((pthread->cancelflags & PTHREAD_AT_CANCEL_POINT) == 0)))
  29                         /* Just mark it for cancellation: */
  30                         pthread->cancelflags |= PTHREAD_CANCELLING;
  31                 else {
  32                         /*
  33                          * Check if we need to kick it back into the
  34                          * run queue:
  35                          */
  36                         switch (pthread->state) {
  37                         case PS_RUNNING:
  38                                 /* No need to resume: */
  39                                 pthread->cancelflags |= PTHREAD_CANCELLING;
  40                                 break;
  41
  42                         case PS_SPINBLOCK:
  43                         case PS_FDR_WAIT:
  44                         case PS_FDW_WAIT:
  45                         case PS_POLL_WAIT:
  46                         case PS_SELECT_WAIT:
  47                                 /* Remove these threads from the work queue: */
  48                                 if ((pthread->flags & PTHREAD_FLAGS_IN_WORKQ)
  49                                     != 0)
  50                                         PTHREAD_WORKQ_REMOVE(pthread);
  51                                 /* Fall through: */
  52                         case PS_SIGTHREAD:
  53                         case PS_SLEEP_WAIT:
  54                         case PS_WAIT_WAIT:
  55                         case PS_SIGSUSPEND:
  56                         case PS_SIGWAIT:
  57                                 /* Interrupt and resume: */
  58                                 pthread->interrupted = 1;
  59                                 pthread->cancelflags |= PTHREAD_CANCELLING;
  60                                 PTHREAD_NEW_STATE(pthread,PS_RUNNING);
  61                                 break;
  62
  63                         case PS_JOIN:
  64                                 /*
  65                                  * Disconnect the thread from the joinee:
  66                                  */
  67                                 if (pthread->join_status.thread != NULL) {
  68                                         pthread->join_status.thread->joiner
  69                                             = NULL;
  70                                         pthread->join_status.thread = NULL;
  71                                 }
  72                                 pthread->cancelflags |= PTHREAD_CANCELLING;
  73                                 PTHREAD_NEW_STATE(pthread, PS_RUNNING);
  74                                 break;
  75
  76                         case PS_SUSPENDED:
  77                         case PS_MUTEX_WAIT:
  78                         case PS_COND_WAIT:
  79                         case PS_FDLR_WAIT:
  80                         case PS_FDLW_WAIT:
  81                                 /*
  82                                  * Threads in these states may be in queues.
  83                                  * In order to preserve queue integrity, the
  84                                  * cancelled thread must remove itself from the
  85                                  * queue.  Mark the thread as interrupted and
  86                                  * needing cancellation, and set the state to
  87                                  * running.  When the thread resumes, it will
  88                                  * remove itself from the queue and call the
  89                                  * cancellation completion routine.
  90                                  */
  91                                 pthread->interrupted = 1;
  92                                 pthread->cancelflags |= PTHREAD_CANCEL_NEEDED;
  93                                 PTHREAD_NEW_STATE(pthread, PS_RUNNING);
  94                                 pthread->continuation = finish_cancellation;
  95                                 break;
  96
  97                         case PS_DEAD:
  98                         case PS_DEADLOCK:
  99                         case PS_STATE_MAX:
 100                                 /* Ignore - only here to silence -Wall: */
 101                                 break;
 102                         }
 103                 }
 104
 105                 /* Unprotect the scheduling queues: */
 106                 _thread_kern_sig_undefer();
 107
 108                 ret = 0;
 109         }
 110         return (ret);
 111 }
 112
 113 int
 114 _pthread_setcancelstate(int state, int *oldstate)
 115 {
 116         struct pthread  *curthread = _get_curthread();
 117         int ostate;
 118         int ret;
 119
 120         ostate = curthread->cancelflags & PTHREAD_CANCEL_DISABLE;
 121
 122         switch (state) {
 123         case PTHREAD_CANCEL_ENABLE:
 124                 if (oldstate != NULL)
 125                         *oldstate = ostate;
 126                 curthread->cancelflags &= ~PTHREAD_CANCEL_DISABLE;
 127                 if ((curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) != 0)
 128                         pthread_testcancel();
 129                 ret = 0;
 130                 break;
 131         case PTHREAD_CANCEL_DISABLE:
 132                 if (oldstate != NULL)
 133                         *oldstate = ostate;
 134                 curthread->cancelflags |= PTHREAD_CANCEL_DISABLE;
 135                 ret = 0;
 136                 break;
 137         default:
 138                 ret = EINVAL;
 139         }
 140
 141         return (ret);
 142 }
 143
 144 int
 145 _pthread_setcanceltype(int type, int *oldtype)
 146 {
 147         struct pthread  *curthread = _get_curthread();
 148         int otype;
 149         int ret;
 150
 151         otype = curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS;
 152         switch (type) {
 153         case PTHREAD_CANCEL_ASYNCHRONOUS:
 154                 if (oldtype != NULL)
 155                         *oldtype = otype;
 156                 curthread->cancelflags |= PTHREAD_CANCEL_ASYNCHRONOUS;
 157                 pthread_testcancel();
 158                 ret = 0;
 159                 break;
 160         case PTHREAD_CANCEL_DEFERRED:
 161                 if (oldtype != NULL)
 162                         *oldtype = otype;
 163                 curthread->cancelflags &= ~PTHREAD_CANCEL_ASYNCHRONOUS;
 164                 ret = 0;
 165                 break;
 166         default:
 167                 ret = EINVAL;
 168         }
 169
 170         return (ret);
 171 }
 172
 173 void
 174 _pthread_testcancel(void)
 175 {
 176         struct pthread  *curthread = _get_curthread();
 177
 178         if (((curthread->cancelflags & PTHREAD_CANCEL_DISABLE) == 0) &&
 179             ((curthread->cancelflags & PTHREAD_CANCELLING) != 0) &&
 180             ((curthread->flags & PTHREAD_EXITING) == 0)) {
 181                 /*
 182                  * It is possible for this thread to be swapped out
 183                  * while performing cancellation; do not allow it
 184                  * to be cancelled again.
 185                  */
 186                 curthread->cancelflags &= ~PTHREAD_CANCELLING;
 187                 _thread_exit_cleanup();
 188                 pthread_exit(PTHREAD_CANCELED);
 189                 PANIC("cancel");
 190         }
 191 }
 192
 193 void
 194 _thread_enter_cancellation_point(void)
 195 {
 196         struct pthread  *curthread = _get_curthread();
 197
 198         /* Look for a cancellation before we block: */
 199         pthread_testcancel();
 200         curthread->cancelflags |= PTHREAD_AT_CANCEL_POINT;
 201 }
 202
 203 void
 204 _thread_leave_cancellation_point(void)
 205 {
 206         struct pthread  *curthread = _get_curthread();
 207
 208         curthread->cancelflags &= ~PTHREAD_AT_CANCEL_POINT;
 209         /* Look for a cancellation after we unblock: */
 210         pthread_testcancel();
 211 }
 212
 213 static void
 214 finish_cancellation(void *arg)
 215 {
 216         struct pthread  *curthread = _get_curthread();
 217
 218         curthread->continuation = NULL;
 219         curthread->interrupted = 0;
 220
 221         if ((curthread->cancelflags & PTHREAD_CANCEL_NEEDED) != 0) {
 222                 curthread->cancelflags &= ~PTHREAD_CANCEL_NEEDED;
 223                 _thread_exit_cleanup();
 224                 pthread_exit(PTHREAD_CANCELED);
 225         }
 226 }
 227
 228 __strong_reference(_pthread_cancel, pthread_cancel);
 229 __strong_reference(_pthread_setcancelstate, pthread_setcancelstate);
 230 __strong_reference(_pthread_setcanceltype, pthread_setcanceltype);
 231 __strong_reference(_pthread_testcancel, pthread_testcancel);