x15/kern/condition.c

/*
 * Copyright (c) 2013-2018 Richard Braun.
 *
 * This program 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.
 *
 * This program 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/>.
 *
 *
 * Locking order : mutex -> sleep queue
 */

#include <assert.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#include <kern/condition.h>
#include <kern/condition_types.h>
#include <kern/mutex.h>
#include <kern/sleepq.h>

static struct sleepq*
condition_sleepq_lend (const void *addr)
{
  union sync_key key;
  sync_key_init (&key, addr);
  key.local.addr |= 1;
  return (sleepq_lend_key (&key));
}

static int
condition_wait_common (struct condition *condition, struct mutex *mutex,
                       bool timed, uint64_t ticks)
{
  assert (mutex_locked (mutex));
  _Auto sleepq = condition_sleepq_lend (condition);

  int error;
  mutex_unlock (mutex);

  if (timed)
    error = sleepq_timedwait (sleepq, "cond", ticks);
  else
    {
      sleepq_wait (sleepq, "cond");
      error = 0;
    }

  sleepq_return (sleepq);
  mutex_lock (mutex);
  return (error);
}

void
condition_wait (struct condition *condition, struct mutex *mutex)
{
  int error = condition_wait_common (condition, mutex, false, 0);
  assert (!error);
}

int
condition_timedwait (struct condition *condition,
                     struct mutex *mutex, uint64_t ticks)
{
  return (condition_wait_common (condition, mutex, true, ticks));
}

static struct sleepq*
condition_sleepq_acquire (const void *addr)
{
  union sync_key key;
  sync_key_init (&key, addr);
  key.local.addr |= 1;
  return (sleepq_acquire_key (&key));
}

void
condition_signal (struct condition *condition)
{
  _Auto sleepq = condition_sleepq_acquire (condition);
  if (! sleepq)
    return;

  sleepq_signal (sleepq);
  sleepq_release (sleepq);
}

void
condition_broadcast (struct condition *condition)
{
  _Auto sleepq = condition_sleepq_acquire (condition);
  if (! sleepq)
    return;

  sleepq_broadcast (sleepq);
  sleepq_release (sleepq);
}