nptl/pthread_cancel.c

   1 /* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <signal.h>
  22 #include "pthreadP.h"
  23 #include "atomic.h"
  24 #include <sysdep.h>
  25 #include <kernel-features.h>
  26
  27
  28 int
  29 pthread_cancel (th)
  30      pthread_t th;
  31 {
  32   volatile struct pthread *pd = (volatile struct pthread *) th;
  33
  34   /* Make sure the descriptor is valid.  */
  35   if (INVALID_TD_P (pd))
  36     /* Not a valid thread handle.  */
  37     return ESRCH;
  38
  39 #ifdef SHARED
  40   pthread_cancel_init ();
  41 #endif
  42   int result = 0;
  43   int oldval;
  44   int newval;
  45   do
  46     {
  47       oldval = pd->cancelhandling;
  48       newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
  49
  50       /* Avoid doing unnecessary work.  The atomic operation can
  51          potentially be expensive if the bug has to be locked and
  52          remote cache lines have to be invalidated.  */
  53       if (oldval == newval)
  54         break;
  55
  56       /* If the cancellation is handled asynchronously just send a
  57          signal.  We avoid this if possible since it's more
  58          expensive.  */
  59       if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
  60         {
  61           /* Mark the cancellation as "in progress".  */
  62           atomic_bit_set (&pd->cancelhandling, CANCELING_BIT);
  63
  64           /* The cancellation handler will take care of marking the
  65              thread as canceled.  */
  66           INTERNAL_SYSCALL_DECL (err);
  67
  68           int val;
  69 #if __ASSUME_TGKILL
  70           val = INTERNAL_SYSCALL (tgkill, err, 3,
  71                                   THREAD_GETMEM (THREAD_SELF, pid), pd->tid,
  72                                   SIGCANCEL);
  73 #else
  74 # ifdef __NR_tgkill
  75           val = INTERNAL_SYSCALL (tgkill, err, 3,
  76                                   THREAD_GETMEM (THREAD_SELF, pid), pd->tid,
  77                                   SIGCANCEL);
  78           if (INTERNAL_SYSCALL_ERROR_P (val, err)
  79               && INTERNAL_SYSCALL_ERRNO (val, err) == ENOSYS)
  80 # endif
  81             val = INTERNAL_SYSCALL (tkill, err, 2, pd->tid, SIGCANCEL);
  82 #endif
  83
  84           if (INTERNAL_SYSCALL_ERROR_P (val, err))
  85             result = INTERNAL_SYSCALL_ERRNO (val, err);
  86
  87           break;
  88         }
  89     }
  90   /* Mark the thread as canceled.  This has to be done
  91      atomically since other bits could be modified as well.  */
  92   while (atomic_compare_and_exchange_bool_acq (&pd->cancelhandling, newval,
  93                                                oldval));
  94
  95   return result;
  96 }