/****************************************************************************
* sched/sched_setscheduler.c
*
* Copyright (C) 2007, 2009, 2012 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 <unistd.h>
#include <sched.h>
#include <errno.h>
#include <nuttx/arch.h>
#include "os_internal.h"
#include "clock_internal.h"
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name:sched_setscheduler
*
* Description:
* sched_setscheduler() sets both the scheduling policy and the priority
* for the task identified by pid. If pid equals zero, the scheduler of
* the calling task will be set. The parameter 'param' holds the priority
* of the thread under the new policy.
*
* Inputs:
* pid - the task ID of the task to modify. If pid is zero, the calling
* task is modified.
* policy - Scheduling policy requested (either SCHED_FIFO or SCHED_RR)
* param - A structure whose member sched_priority is the new priority.
* The range of valid priority numbers is from SCHED_PRIORITY_MIN
* through SCHED_PRIORITY_MAX.
*
* Return Value:
* On success, sched_setscheduler() returns OK (zero). On error, ERROR
* (-1) is returned, and errno is set appropriately:
*
* EINVAL The scheduling policy is not one of the recognized policies.
* ESRCH The task whose ID is pid could not be found.
*
* Assumptions:
*
****************************************************************************/
int sched_setscheduler(pid_t pid, int policy,
const struct sched_param *param)
{
FAR struct tcb_s *tcb;
#if CONFIG_RR_INTERVAL > 0
irqstate_t saved_state;
#endif
int ret;
/* Check for supported scheduling policy */
#if CONFIG_RR_INTERVAL > 0
if (policy != SCHED_FIFO && policy != SCHED_RR)
#else
if (policy != SCHED_FIFO)
#endif
{
errno = EINVAL;
return ERROR;
}
/* Check if the task to modify the calling task */
if (pid == 0 )
{
pid = getpid();
}
/* Verify that the pid corresponds to a real task */
tcb = sched_gettcb(pid);
if (!tcb)
{
errno = ESRCH;
return ERROR;
}
/* Prohibit any context switches while we muck with priority and scheduler
* settings.
*/
sched_lock();
#if CONFIG_RR_INTERVAL > 0
/* Further, disable timer interrupts while we set up scheduling policy. */
saved_state = irqsave();
if (policy == SCHED_RR)
{
/* Set round robin scheduling */
tcb->flags |= TCB_FLAG_ROUND_ROBIN;
tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
}
else
{
/* Set FIFO scheduling */
tcb->flags &= ~TCB_FLAG_ROUND_ROBIN;
tcb->timeslice = 0;
}
irqrestore(saved_state);
#endif
/* Set the new priority */
ret = sched_reprioritize(tcb, param->sched_priority);
sched_unlock();
if (ret != OK)
{
return ERROR;
}
else
{
return OK;
}
}
