text: /****************************************************************************
   * sched/signal/sig_evthread.c
   *
   *   Copyright (C) 2015, 2017-2018 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 <sys/types.h>
  #include <signal.h>
  #include <assert.h>
  #include <errno.h>
  
  #include <nuttx/kmalloc.h>
  #include <nuttx/wqueue.h>
  
  #ifdef CONFIG_SIG_EVTHREAD
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /* Use the low-prioriry work queue is it is available */
  
  #if defined(CONFIG_SCHED_LPWORK)
  #  define NTWORK LPWORK
  #elif defined(CONFIG_SCHED_HPWORK)
  #  define NTWORK HPWORK
  #else
  #  error Work queue is not enabled
  #endif
  
  /****************************************************************************
   * Private Type Definitions
   ****************************************************************************/
  
  /* This structure retains all that is necessary to perform the notification */
  
  struct sig_evthread_s
  {
    struct work_s nt_work;           /* Work queue structure */
    union sigval nt_value;           /* Data passed with notification */
    sigev_notify_function_t nt_func; /* Notification function */
  };
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: nxsig_evthread_worker
   *
   * Description:
   *   Perform the callback from the context of the worker thread.
   *
   * Input Parameters:
   *   arg - Work argument.
   *
   * Returned Value:
   *   None.
   *
   ****************************************************************************/
  
  static void nxsig_evthread_worker(FAR void *arg)
  {
    FAR struct sig_evthread_s *notify = (FAR struct sig_evthread_s *)arg;
  
    DEBUGASSERT(notify != NULL);
  
    /* Perform the callback */
  
  #ifdef CONFIG_CAN_PASS_STRUCTS
    notify->nt_func(notify->nt_value);
  #else
    notify->nt_func(notify->nt_value.sival_ptr);
  #endif
  
    /* Free the alloated notification parameters */
  
    kmm_free(notify);
  }
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: nxsig_evthread
   *
   * Description:
   *   Notify a client a signal event via a function call.  This function is
   *   an internal OS interface that implements the common logic for signal
   *   event notification for the case of SIGEV_THREAD.
   *
   * Input Parameters:
   *   pid   - The task/thread ID a the client thread to be signaled.
   *   event - The instance of struct sigevent that describes how to signal
   *           the client.
   *
   * Returned Value:
   *   This is an internal OS interface and should not be used by applications.
   *   It follows the NuttX internal error return policy:  Zero (OK) is
   *   returned on success.  A negated errno value is returned on failure.
   *
   ****************************************************************************/
  
  int nxsig_evthread(pid_t pid, FAR struct sigevent *event)
  {
    FAR struct sig_evthread_s *notify;
    DEBUGASSERT(event != NULL && event->sigev_notify_function != NULL);
    int ret;
  
    /* Allocate a structure to hold the notification information */
  
    notify = kmm_zalloc(sizeof(struct sig_evthread_s));
    if (notify == NULL)
      {
        return -ENOMEM;
      }
  
    /* Initialize the notification information */
  
  #ifdef CONFIG_CAN_PASS_STRUCTS
    notify->nt_value = event->sigev_value;
  #else
    notify->nt_value.sival_ptr = event->sigev_value.sival_ptr;
  #endif
    notify->nt_func = event->sigev_notify_function;
  
    /* Then queue the work */
  
    ret = work_queue(NTWORK, &notify->nt_work, nxsig_evthread_worker,
                     notify, 0);
    if (ret < 0)
      {
        kmm_free(notify);
      }
  
    return ret;
  }
  
  #endif /* CONFIG_SIG_EVTHREAD */
  