150 lines
4.3 KiB
C
150 lines
4.3 KiB
C
/****************************************************************************
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* mm/mm_heap/mm_sem.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 <unistd.h>
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#include <errno.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/arch.h>
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#include <nuttx/semaphore.h>
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#include <nuttx/mm/mm.h>
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#include "mm_heap/mm.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mm_seminitialize
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*
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* Description:
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* Initialize the MM mutex
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*
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****************************************************************************/
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void mm_seminitialize(FAR struct mm_heap_s *heap)
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{
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/* Initialize the MM semaphore to one (to support one-at-a-time access to
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* private data sets).
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*/
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_SEM_INIT(&heap->mm_semaphore, 0, 1);
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}
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/****************************************************************************
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* Name: mm_takesemaphore
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*
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* Description:
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* Take the MM mutex. This may be called from the OS in certain conditions
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* when it is impossible to wait on a semaphore:
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* 1.The idle process performs the memory corruption check.
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* 2.The task/thread free the memory in the exiting process.
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*
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* Input Parameters:
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* heap - heap instance want to take semaphore
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*
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* Returned Value:
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* true if the semaphore can be taken, otherwise false.
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*
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****************************************************************************/
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bool mm_takesemaphore(FAR struct mm_heap_s *heap)
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{
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#if defined(CONFIG_BUILD_FLAT) || defined(__KERNEL__)
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/* Check current environment */
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if (up_interrupt_context())
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{
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/* Can't take semaphore in the interrupt handler */
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return false;
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}
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else
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#endif
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/* getpid() returns the task ID of the task at the head of the ready-to-
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* run task list. mm_takesemaphore() may be called during context
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* switches. There are certain situations during context switching when
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* the OS data structures are in flux and then can't be freed immediately
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* (e.g. the running thread stack).
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*
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* This is handled by getpid() to return the special value -ESRCH to
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* indicate this special situation.
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*/
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if (getpid() < 0)
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{
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return false;
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}
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#if defined(CONFIG_BUILD_FLAT) || defined(__KERNEL__)
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else if (sched_idletask())
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{
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/* Try to take the semaphore */
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return _SEM_TRYWAIT(&heap->mm_semaphore) >= 0;
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}
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#endif
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else
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{
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int ret;
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/* Take the semaphore (perhaps waiting) */
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do
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{
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ret = _SEM_WAIT(&heap->mm_semaphore);
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/* The only case that an error should occur here is if the wait
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* was awakened by a signal.
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*/
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if (ret < 0)
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{
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ret = _SEM_ERRVAL(ret);
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DEBUGASSERT(ret == -EINTR || ret == -ECANCELED);
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}
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}
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while (ret < 0);
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return true;
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}
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}
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/****************************************************************************
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* Name: mm_givesemaphore
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*
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* Description:
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* Release the MM mutex when it is not longer needed.
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*
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****************************************************************************/
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void mm_givesemaphore(FAR struct mm_heap_s *heap)
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{
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DEBUGVERIFY(_SEM_POST(&heap->mm_semaphore));
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}
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