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 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 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_preemptor *preemptor)
  25 {
  26   __mutex_lock (&_hurd_siglock);
  27   preemptor->next = _hurdsig_preemptors;
  28   _hurdsig_preemptors = preemptor;
  29   _hurdsig_preempted_set |= preemptor->signals;
  30   __mutex_unlock (&_hurd_siglock);
  31 }
  32
  33 void
  34 hurd_unpreempt_signals (struct hurd_signal_preemptor *preemptor)
  35 {
  36   struct hurd_signal_preemptor **p;
  37   sigset_t preempted = 0;
  38
  39   __mutex_lock (&_hurd_siglock);
  40
  41   p = &_hurdsig_preemptors;
  42   while (*p)
  43     if (*p == preemptor)
  44       {
  45         /* Found it; take it off the chain.  */
  46         *p = (*p)->next;
  47         if ((preemptor->signals & preempted) != preemptor->signals)
  48           {
  49             /* This might have been the only preemptor for some
  50                of those signals, so we must collect the full mask
  51                from the others.  */
  52             struct hurd_signal_preemptor *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 preemptor");
  68 }