hurd/preempt-sig.c

   1 /* Copyright (C) 1994-2017 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    <http://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 }