hurd/thread-cancel.c

   1 /* Thread cancellation support.
   2    Copyright (C) 1995, 1996, 1997, 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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 <hurd/signal.h>
  21 #include <hurd/interrupt.h>
  22 #include <assert.h>
  23 #include <thread_state.h>
  24
  25
  26 /* See hurdsig.c.  */
  27 extern mach_port_t _hurdsig_abort_rpcs (struct hurd_sigstate *ss,
  28                                         int signo, int sigthread,
  29                                         struct machine_thread_all_state *,
  30                                         int *state_change,
  31                                         mach_port_t *reply_port,
  32                                         mach_msg_type_name_t reply_port_type,
  33                                         int untraced);
  34
  35 error_t
  36 hurd_thread_cancel (thread_t thread)
  37 {
  38   struct hurd_sigstate *ss = _hurd_thread_sigstate (thread);
  39   struct machine_thread_all_state state;
  40   int state_change;
  41   error_t err;
  42
  43   if (! ss)
  44     return EINVAL;
  45   if (ss == _hurd_self_sigstate ())
  46     {
  47       /* We are cancelling ourselves, so it is easy to succeed
  48          quickly.  Since this function is not a cancellation point, we
  49          just leave the flag set pending the next cancellation point
  50          (hurd_check_cancel or RPC) and return success.  */
  51       ss->cancel = 1;
  52       return 0;
  53     }
  54
  55   assert (! __spin_lock_locked (&ss->critical_section_lock));
  56   __spin_lock (&ss->critical_section_lock);
  57   __spin_lock (&ss->lock);
  58   err = __thread_suspend (thread);
  59   __spin_unlock (&ss->lock);
  60
  61   if (! err)
  62     {
  63       /* Set the flag telling the thread its operation is being cancelled.  */
  64       ss->cancel = 1;
  65
  66       /* Interrupt any interruptible RPC now in progress.  */
  67       state.set = 0;
  68       _hurdsig_abort_rpcs (ss, 0, 0, &state, &state_change, NULL, 0, 0);
  69       if (state_change)
  70         err = __thread_set_state (thread, MACHINE_THREAD_STATE_FLAVOR,
  71                                   (natural_t *) &state.basic,
  72                                   MACHINE_THREAD_STATE_COUNT);
  73
  74       if (ss->cancel_hook)
  75         /* The code being cancelled has a special wakeup function.
  76            Calling this should make the thread wake up and check the
  77            cancellation flag.  */
  78         (*ss->cancel_hook) ();
  79
  80       __thread_resume (thread);
  81     }
  82
  83   _hurd_critical_section_unlock (ss);
  84   return err;
  85 }
  86
  87
  88 int
  89 hurd_check_cancel (void)
  90 {
  91   struct hurd_sigstate *ss = _hurd_self_sigstate ();
  92   int cancel;
  93
  94   __spin_lock (&ss->lock);
  95   assert (! __spin_lock_locked (&ss->critical_section_lock));
  96   cancel = ss->cancel;
  97   ss->cancel = 0;
  98   __spin_unlock (&ss->lock);
  99
 100   return cancel;
 101 }