1  /* Copyright (C) 1994-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <hurd/sigpreempt.h>
      19  #include <hurd/signal.h>
      20  #include <assert.h>
      21  
      22  void
      23  hurd_preempt_signals (struct hurd_signal_preemptor *preemptor)
      24  {
      25    __mutex_lock (&_hurd_siglock);
      26    preemptor->next = _hurdsig_preemptors;
      27    _hurdsig_preemptors = preemptor;
      28    _hurdsig_preempted_set |= preemptor->signals;
      29    __mutex_unlock (&_hurd_siglock);
      30  }
      31  
      32  void
      33  hurd_unpreempt_signals (struct hurd_signal_preemptor *preemptor)
      34  {
      35    struct hurd_signal_preemptor **p;
      36    sigset_t preempted = 0;
      37  
      38    __mutex_lock (&_hurd_siglock);
      39  
      40    p = &_hurdsig_preemptors;
      41    while (*p)
      42      if (*p == preemptor)
      43        {
      44  	/* Found it; take it off the chain.  */
      45  	*p = (*p)->next;
      46  	if ((preemptor->signals & preempted) != preemptor->signals)
      47  	  {
      48  	    /* This might have been the only preemptor for some
      49  	       of those signals, so we must collect the full mask
      50  	       from the others.  */
      51  	    struct hurd_signal_preemptor *pp;
      52  	    for (pp = *p; pp; pp = pp->next)
      53  	      preempted |= pp->signals;
      54  	    _hurdsig_preempted_set = preempted;
      55  	  }
      56  	__mutex_unlock (&_hurd_siglock);
      57  	return;
      58        }
      59      else
      60        {
      61  	preempted |= (*p)->signals;
      62  	p = &(*p)->next;
      63        }
      64  
      65    __mutex_unlock (&_hurd_siglock); /* Avoid deadlock during death rattle.  */
      66    assert (! "removing absent preemptor");
      67  }