98ab55ef68
to avoid to generate the unexpected schedule information Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
93 lines
3.1 KiB
C
93 lines
3.1 KiB
C
/****************************************************************************
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* sched/sched/sched_gettcb.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 <sys/types.h>
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#include <sched.h>
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#include "nuttx/irq.h"
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#include "sched/sched.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsched_get_tcb
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*
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* Description:
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* Given a task ID, this function will return the a pointer to the
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* corresponding TCB (or NULL if there is no such task ID).
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*
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* NOTE: This function holds a critical section while examining TCB data
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* data structures but releases that critical section before returning.
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* When it is released, the TCB may become unstable. If the caller
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* requires absolute stability while using the TCB, then the caller
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* should establish the critical section BEFORE calling this function and
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* hold that critical section as long as necessary.
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*
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****************************************************************************/
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FAR struct tcb_s *nxsched_get_tcb(pid_t pid)
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{
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FAR struct tcb_s *ret = NULL;
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irqstate_t flags;
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int hash_ndx;
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flags = spin_lock_irqsave_wo_note(NULL);
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/* Verify whether g_pidhash hash table has already been allocated and
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* whether the PID is within range.
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*/
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if (g_pidhash != NULL && pid >= 0)
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{
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/* The test and the return setup should be atomic. This still does
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* not provide proper protection if the recipient of the TCB does not
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* also protect against the task associated with the TCB from
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* terminating asynchronously.
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*/
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/* Get the hash_ndx associated with the pid */
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hash_ndx = PIDHASH(pid);
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/* Verify that the correct TCB was found. */
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if (g_pidhash[hash_ndx] != NULL && pid == g_pidhash[hash_ndx]->pid)
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{
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/* Return the TCB associated with this pid (if any) */
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ret = g_pidhash[hash_ndx];
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}
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}
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spin_unlock_irqrestore_wo_note(NULL, flags);
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/* Return the TCB. */
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return ret;
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}
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