hurd/thread-cancel.c

   1 /* Thread cancellation support.
   2    Copyright (C) 1995-2021 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 /* See hurdsig.c.  */
  26 extern mach_port_t _hurdsig_abort_rpcs (struct hurd_sigstate *ss,
  27                                         int signo, int sigthread,
  28                                         struct machine_thread_all_state *,
  29                                         int *state_change,
  30                                         mach_port_t *reply_port,
  31                                         mach_msg_type_name_t reply_port_type,
  32                                         int untraced);
  33
  34 error_t
  35 hurd_thread_cancel (thread_t thread)
  36 {
  37   struct hurd_sigstate *ss = _hurd_thread_sigstate (thread);
  38   struct machine_thread_all_state state;
  39   int state_change;
  40   error_t err;
  41
  42   if (! ss)
  43     return EINVAL;
  44   if (ss == _hurd_self_sigstate ())
  45     {
  46       /* We are cancelling ourselves, so it is easy to succeed
  47          quickly.  Since this function is not a cancellation point, we
  48          just leave the flag set pending the next cancellation point
  49          (hurd_check_cancel or RPC) and return success.  */
  50       ss->cancel = 1;
  51       return 0;
  52     }
  53
  54   assert (! __spin_lock_locked (&ss->critical_section_lock));
  55   __spin_lock (&ss->critical_section_lock);
  56   __spin_lock (&ss->lock);
  57   err = __thread_suspend (thread);
  58   __spin_unlock (&ss->lock);
  59
  60   if (! err)
  61     {
  62       /* Set the flag telling the thread its operation is being cancelled.  */
  63       ss->cancel = 1;
  64
  65       /* Interrupt any interruptible RPC now in progress.  */
  66       state.set = 0;
  67       _hurdsig_abort_rpcs (ss, 0, 0, &state, &state_change, NULL, 0, 0);
  68       if (state_change)
  69         err = __thread_set_state (thread, MACHINE_THREAD_STATE_FLAVOR,
  70                                   (natural_t *) &state.basic,
  71                                   MACHINE_THREAD_STATE_COUNT);
  72
  73       if (ss->cancel_hook)
  74         /* The code being cancelled has a special wakeup function.
  75            Calling this should make the thread wake up and check the
  76            cancellation flag.  */
  77         (*ss->cancel_hook) ();
  78
  79       __thread_resume (thread);
  80     }
  81
  82   _hurd_critical_section_unlock (ss);
  83   return err;
  84 }
  85
  86
  87 int
  88 hurd_check_cancel (void)
  89 {
  90   struct hurd_sigstate *ss = _hurd_self_sigstate ();
  91   int cancel;
  92
  93   __spin_lock (&ss->lock);
  94   assert (! __spin_lock_locked (&ss->critical_section_lock));
  95   cancel = ss->cancel;
  96   ss->cancel = 0;
  97   __spin_unlock (&ss->lock);
  98
  99   return cancel;
 100 }