/* bottom-half.c - Bottom half implementation.
   Copyright (C) 2009 Free Software Foundation, Inc.
   Written by Neal H. Walfield <neal@gnu.org>.

   This file is part of the GNU Hurd.

   The GNU Hurd is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 3 of the
   License, or (at your option) any later version.

   The GNU Hurd is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see
   <http://www.gnu.org/licenses/>.  */

#include "bottom-half.h"

struct bottom_half *bottom_halves;

void
bottom_half_register (struct bottom_half *bh)
{
  assert (! bh->next);
  assert (bh != bottom_halves);

  do
    bh->next = bottom_halves;
  while (__sync_val_compare_and_swap (&bottom_halves, bh->next, bh)
	 != bh->next);
}

void
bottom_half_run_hard (void)
{
  struct bottom_half *bh;

  do
    bh = bottom_halves;
  while (bh && !__sync_val_compare_and_swap (&bottom_halves, bh, 0));

  if (! bh)
    return;

  struct bottom_half *next = bh;
  while ((bh = next))
    {
      next = bh->next;

      bh->next = 0;
      bh->callback (bh);
    }
}