105 lines
3.2 KiB
C
105 lines
3.2 KiB
C
/****************************************************************************
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* sched/sched/sched_cpupause.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/arch.h>
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#include <nuttx/sched_note.h>
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#include "sched/sched.h"
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#ifdef CONFIG_SMP
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsched_pause_cpu
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*
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* Description:
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* Check if task associated with 'tcb' is running on a different CPU. If
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* so then pause that CPU and return its CPU index.
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*
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* Input Parameters:
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* tcb - The TCB of the task to be conditionally paused.
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*
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* Returned Value:
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* If a CPU is pauses its non-negative CPU index is returned. This index
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* may then be used to resume the CPU. If the task is not running at all
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* (or if an error occurs), then a negated errno value is returned. -ESRCH
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* is returned in the case where the task is not running on any CPU.
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*
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* Assumptions:
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* This function was called in a critical section. In that case, no tasks
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* may started or may exit until the we leave the critical section. This
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* critical section should extend until up_cpu_resume() is called in the
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* typical case.
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*
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****************************************************************************/
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int nxsched_pause_cpu(FAR struct tcb_s *tcb)
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{
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int cpu;
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int ret;
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DEBUGASSERT(tcb != NULL);
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/* If the task is not running at all then our job is easy */
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cpu = tcb->cpu;
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if (tcb->task_state != TSTATE_TASK_RUNNING)
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{
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return -ESRCH;
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}
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/* Check the CPU that the task is running on */
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DEBUGASSERT(cpu != this_cpu() && (unsigned int)cpu < CONFIG_SMP_NCPUS);
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if (cpu == this_cpu())
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{
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/* We can't pause ourself */
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return -EACCES;
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}
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/* Pause the CPU that the task is running on */
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ret = up_cpu_pause(cpu);
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if (ret < 0)
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{
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return ret;
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}
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/* Return the CPU that the task is running on */
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return cpu;
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}
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#endif /* CONFIG_SMP */
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