hurd/thread-cancel.c

   1 /* Thread cancellation support.
   2    Copyright (C) 1995-2023 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, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <hurd/signal.h>
  20 #include <hurd/interrupt.h>
  21 #include <assert.h>
  22 #include <thread_state.h>
  23
  24
  25 error_t
  26 hurd_thread_cancel (thread_t thread)
  27 {
  28   struct hurd_sigstate *ss = _hurd_thread_sigstate (thread);
  29   struct machine_thread_all_state state;
  30   int state_change;
  31   error_t err;
  32
  33   if (! ss)
  34     return EINVAL;
  35   if (ss == _hurd_self_sigstate ())
  36     {
  37       /* We are cancelling ourselves, so it is easy to succeed
  38          quickly.  Since this function is not a cancellation point, we
  39          just leave the flag set pending the next cancellation point
  40          (hurd_check_cancel or RPC) and return success.  */
  41       ss->cancel = 1;
  42       return 0;
  43     }
  44
  45   assert (! __spin_lock_locked (&ss->critical_section_lock));
  46   __spin_lock (&ss->critical_section_lock);
  47   __spin_lock (&ss->lock);
  48   err = __thread_suspend (thread);
  49   __spin_unlock (&ss->lock);
  50
  51   if (! err)
  52     {
  53       /* Set the flag telling the thread its operation is being cancelled.  */
  54       ss->cancel = 1;
  55
  56       /* Interrupt any interruptible RPC now in progress.  */
  57       state.set = 0;
  58       _hurdsig_abort_rpcs (ss, 0, 0, &state, &state_change, NULL);
  59       if (state_change)
  60         err = __thread_set_state (thread, MACHINE_THREAD_STATE_FLAVOR,
  61                                   (natural_t *) &state.basic,
  62                                   MACHINE_THREAD_STATE_COUNT);
  63
  64       if (ss->cancel_hook)
  65         /* The code being cancelled has a special wakeup function.
  66            Calling this should make the thread wake up and check the
  67            cancellation flag.  */
  68         (*ss->cancel_hook) ();
  69
  70       __thread_resume (thread);
  71     }
  72
  73   _hurd_critical_section_unlock (ss);
  74   return err;
  75 }
  76
  77
  78 int
  79 hurd_check_cancel (void)
  80 {
  81   struct hurd_sigstate *ss = _hurd_self_sigstate ();
  82   int cancel;
  83
  84   __spin_lock (&ss->lock);
  85   assert (! __spin_lock_locked (&ss->critical_section_lock));
  86   cancel = ss->cancel;
  87   ss->cancel = 0;
  88   __spin_unlock (&ss->lock);
  89
  90   return cancel;
  91 }