/*
 * Copyright (c) 2020 Red Hat, Inc.
 *
 * 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA. 
 *
 * $Id: //eng/vdo-releases/aluminum/src/c++/vdo/kernel/threadRegistry.c#1 $
 */

#include "threadRegistry.h"

#include <linux/gfp.h>
#include <linux/slab.h>

#include "permassert.h"

/*
 * We need to be careful when using other facilities that may use
 * threadRegistry functions in their normal operation.  For example,
 * we do not want to invoke the logger while holding a lock.
 */

/*****************************************************************************/
void registerThread(ThreadRegistry   *registry,
                    RegisteredThread *newThread,
                    const void       *pointer)
{
  INIT_LIST_HEAD(&newThread->links);
  newThread->pointer = pointer;
  newThread->task    = current;

  bool foundIt = false;
  RegisteredThread *thread;
  write_lock(&registry->lock);
  list_for_each_entry(thread, &registry->links, links) {
    if (thread->task == current) {
      // This should not have been there.
      // We'll complain after releasing the lock.
      list_del_init(&thread->links);
      foundIt = true;
      break;
    }
  }
  list_add_tail(&newThread->links, &registry->links);
  write_unlock(&registry->lock);
  ASSERT_LOG_ONLY(!foundIt, "new thread not already in registry");
}

/*****************************************************************************/
void unregisterThread(ThreadRegistry *registry)
{
  bool foundIt = false;
  RegisteredThread *thread;
  write_lock(&registry->lock);
  list_for_each_entry(thread, &registry->links, links) {
    if (thread->task == current) {
      list_del_init(&thread->links);
      foundIt = true;
      break;
    }
  }
  write_unlock(&registry->lock);
  ASSERT_LOG_ONLY(foundIt, "thread found in registry");
}

/*****************************************************************************/
void initializeThreadRegistry(ThreadRegistry *registry)
{
  INIT_LIST_HEAD(&registry->links);
  rwlock_init(&registry->lock);
}

/*****************************************************************************/
const void *lookupThread(ThreadRegistry *registry)
{
  const void *result = NULL;
  read_lock(&registry->lock);
  RegisteredThread *thread;
  list_for_each_entry(thread, &registry->links, links) {
    if (thread->task == current) {
      result = thread->pointer;
      break;
    }
  }
  read_unlock(&registry->lock);
  return result;
}