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  /* 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  }