nuttx/sched/pthread/pthread_keycreate.c

/****************************************************************************
 * sched/pthread/pthread_keycreate.c
 *
 *   Copyright (C) 2007-2009, 2013, 2018 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sched.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>

#include <nuttx/irq.h>

#include "sched/sched.h"
#include "pthread/pthread.h"

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: pthread_key_create
 *
 * Description:
 *   This function creates a thread-specific data key visible to all threads
 *   in the system.  Although the same key value may be used by different
 *   threads, the values bound to the key by pthread_setspecific() are
 *   maintained on a per-thread basis and persist for the life of the calling
 *   thread.
 *
 *   Upon key creation, the value NULL will be associated with the new key
 *   in all active threads.  Upon thread creation, the value NULL will be
 *   associated with all defined keys in the new thread.
 *
 * Input Parameters:
 *   key        - A pointer to the key to create.
 *   destructor - An optional destructor() function that may be associated
 *                with each key that is invoked when a thread exits.
 *                However, this argument is ignored in the current
 *                implementation.
 *
 * Returned Value:
 *   If successful, the pthread_key_create() function will store the newly
 *   created key value at *key and return zero (OK).  Otherwise, an error
 *   number will be returned to indicate the error:
 *
 *      EAGAIN  - The system lacked sufficient resources to create another
 *                thread-specific data key, or the system-imposed limit on
 *                the total number of keys pers process {PTHREAD_KEYS_MAX}
 *                has been exceeded
 *      ENOMEM  - Insufficient memory exist to create the key.
 *
 * POSIX Compatibility:
 *   - The present implementation ignores the destructor argument.
 *
 ****************************************************************************/

int pthread_key_create(FAR pthread_key_t *key,
                       CODE void (*destructor)(FAR void *))
{
#if CONFIG_NPTHREAD_KEYS > 0
  FAR struct tcb_s *rtcb = this_task();
  FAR struct task_group_s *group = rtcb->group;
  irqstate_t flags;
  int candidate;
  int ret = EAGAIN;

  DEBUGASSERT(key != NULL && group != NULL);

  /* Search for an unused key.  This is done in a critical section here to
   * avoid concurrent modification of the group keyset.
   */

  flags = spin_lock_irqsave();
  for (candidate = 0; candidate < PTHREAD_KEYS_MAX; candidate++)
    {
      /* Is this candidate key available? */

      pthread_keyset_t mask = (1 << candidate);
      if ((group->tg_keyset & mask) == 0)
        {
          /* Yes.. allocate the key and break out of the loop */

          group->tg_keyset |= mask;
          break;
        }
    }

  spin_unlock_irqrestore(flags);

  /* Check if found a valid key. */

  if (candidate < PTHREAD_KEYS_MAX)
    {
      /* Yes.. Return the key value and success */

      *key = candidate;
      ret  = OK;
    }

  return ret;
#else
  return ENOSYS;
#endif
}