/*

 * 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;

}