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-rw-r--r--nuttx/mm/mm_sem.c247
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diff --git a/nuttx/mm/mm_sem.c b/nuttx/mm/mm_sem.c
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-/****************************************************************************
- * mm/mm_sem.c
- *
- * Copyright (C) 2007-2009 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 "mm_environment.h"
-
-#include <unistd.h>
-#include <semaphore.h>
-#include <errno.h>
-#include <assert.h>
-
-#include "mm_internal.h"
-
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/* Define the following to enable semaphore state monitoring */
-//#define MONITOR_MM_SEMAPHORE 1
-
-#ifdef MONITOR_MM_SEMAPHORE
-# ifdef CONFIG_DEBUG
-# include <debug.h>
-# define msemdbg dbg
-# else
-# define msemdbg printf
-# endif
-#else
-# ifdef CONFIG_CPP_HAVE_VARARGS
-# define msemdbg(x...)
-# else
-# define msemdbg (void)
-# endif
-#endif
-
-/****************************************************************************
- * Private Data
- ****************************************************************************/
-
-/* Mutually exclusive access to this data set is enforced with
- * the following (un-named) semaphore. */
-
-static sem_t g_mm_semaphore;
-static pid_t g_holder;
-static int g_counts_held;
-
-/****************************************************************************
- * Public Functions
- ****************************************************************************/
-
-/****************************************************************************
- * Name: mm_seminitialize
- *
- * Description:
- * Initialize the MM mutex
- *
- ****************************************************************************/
-
-void mm_seminitialize(void)
-{
- /* Initialize the MM semaphore to one (to support one-at-a-time access to
- * private data sets.
- */
-
- (void)sem_init(&g_mm_semaphore, 0, 1);
-
- g_holder = -1;
- g_counts_held = 0;
-}
-
-/****************************************************************************
- * Name: mm_trysemaphore
- *
- * Description:
- * Try to take the MM mutex. This is called only from the OS in certain
- * conditions when it is necessary to have exclusive access to the memory
- * manager but it is impossible to wait on a semaphore (e.g., the idle
- * process when it performs its background memory cleanup).
- *
- ****************************************************************************/
-
-#ifndef MM_TEST
-int mm_trysemaphore(void)
-{
- pid_t my_pid = getpid();
-
- /* Do I already have the semaphore? */
-
- if (g_holder == my_pid)
- {
- /* Yes, just increment the number of references that I have */
-
- g_counts_held++;
- return OK;
- }
- else
- {
- /* Try to take the semaphore (perhaps waiting) */
-
- if (sem_trywait(&g_mm_semaphore) != 0)
- {
- return ERROR;
- }
-
- /* We have it. Claim the stak and return */
-
- g_holder = my_pid;
- g_counts_held = 1;
- return OK;
- }
-}
-#endif
-
-/****************************************************************************
- * Name: mm_takesemaphore
- *
- * Description:
- * Take the MM mutex. This is the normal action before all memory
- * management actions.
- *
- ****************************************************************************/
-
-void mm_takesemaphore(void)
-{
- pid_t my_pid = getpid();
-
- /* Do I already have the semaphore? */
-
- if (g_holder == my_pid)
- {
- /* Yes, just increment the number of references that I have */
-
- g_counts_held++;
- }
- else
- {
- /* Take the semaphore (perhaps waiting) */
-
- msemdbg("PID=%d taking\n", my_pid);
- while (sem_wait(&g_mm_semaphore) != 0)
- {
- /* The only case that an error should occur here is if
- * the wait was awakened by a signal.
- */
-
- ASSERT(mm_errno == EINTR);
- }
-
- /* We have it. Claim the stake and return */
-
- g_holder = my_pid;
- g_counts_held = 1;
- }
-
- msemdbg("Holder=%d count=%d\n", g_holder, g_counts_held);
-}
-
-/****************************************************************************
- * Name: mm_givesemaphore
- *
- * Description:
- * Release the MM mutex when it is not longer needed.
- *
- ****************************************************************************/
-
-void mm_givesemaphore(void)
-{
-#ifdef CONFIG_DEBUG
- pid_t my_pid = getpid();
-#endif
-
- /* I better be holding at least one reference to the semaphore */
-
- DEBUGASSERT(g_holder == my_pid);
-
- /* Do I hold multiple references to the semphore */
-
- if (g_counts_held > 1)
- {
- /* Yes, just release one count and return */
-
- g_counts_held--;
- msemdbg("Holder=%d count=%d\n", g_holder, g_counts_held);
- }
- else
- {
- /* Nope, this is the last reference I have */
-
- msemdbg("PID=%d giving\n", my_pid);
- g_holder = -1;
- g_counts_held = 0;
- ASSERT(sem_post(&g_mm_semaphore) == 0);
- }
-}
-
-/****************************************************************************
- * Name: mm_getsemaphore
- *
- * Description:
- * Return the current value of the MM semaphore (for test purposes only)
- *
- ****************************************************************************/
-
-#ifdef MM_TEST
-int mm_getsemaphore(void)
-{
- int sval;
- sem_getvalue(&g_mm_semaphore, &sval);
- return sval;
-}
-#endif
-
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