hurd/preempt-sig.c

   1 /* Copyright (C) 1994, 1995, 1996 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 Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 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 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <hurd/sigpreempt.h>
  20 #include <hurd/signal.h>
  21 #include <assert.h>
  22
  23 void
  24 hurd_preempt_signals (struct hurd_signal_preempter *preempter)
  25 {
  26   __mutex_lock (&_hurd_siglock);
  27   preempter->next = _hurdsig_preempters;
  28   _hurdsig_preempters = preempter;
  29   _hurdsig_preempted_set |= preempter->signals;
  30   __mutex_unlock (&_hurd_siglock);
  31 }
  32
  33 void
  34 hurd_unpreempt_signals (struct hurd_signal_preempter *preempter)
  35 {
  36   struct hurd_signal_preempter **p;
  37   sigset_t preempted = 0;
  38
  39   __mutex_lock (&_hurd_siglock);
  40
  41   p = &_hurdsig_preempters;
  42   while (*p)
  43     if (*p == preempter)
  44       {
  45         /* Found it; take it off the chain.  */
  46         *p = (*p)->next;
  47         if ((preempter->signals & preempted) != preempter->signals)
  48           {
  49             /* This might have been the only preempter for some
  50                of those signals, so we must collect the full mask
  51                from the others.  */
  52             struct hurd_signal_preempter *pp;
  53             for (pp = *p; pp; pp = pp->next)
  54               preempted |= pp->signals;
  55             _hurdsig_preempted_set = preempted;
  56           }
  57         __mutex_unlock (&_hurd_siglock);
  58         return;
  59       }
  60     else
  61       {
  62         preempted |= (*p)->signals;
  63         p = &(*p)->next;
  64       }
  65
  66   __mutex_unlock (&_hurd_siglock); /* Avoid deadlock during death rattle.  */
  67   assert (! "removing absent preempter");
  68 }