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/************************************************************
* sched_setscheduler.c
*
* Copyright (C) 2007 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 Gregory Nutt 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 <nuttx/os_external.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 _TCB *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
{
*get_errno_ptr() = 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)
{
*get_errno_ptr() = 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_setparam(pid, param);
sched_unlock();
if (ret != OK)
{
return ERROR;
}
else
{
return SCHED_FIFO;
}
}
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