9568600ab1
This commit backs out most of commit b4747286b1. That change was added because sem_wait() would sometimes cause cancellation points inappropriated. But with these recent changes, nxsem_wait() is used instead and it is not a cancellation point.
In the OS, all calls to sem_wait() changed to nxsem_wait(). nxsem_wait() does not return errors via errno so each place where nxsem_wait() is now called must not examine the errno variable.
In all OS functions (not libraries), change sem_wait() to nxsem_wait(). This will prevent the OS from creating bogus cancellation points and from modifying the per-task errno variable.
sched/semaphore: Add the function nxsem_wait(). This is a new internal OS interface. It is functionally equivalent to sem_wait() except that (1) it is not a cancellation point, and (2) it does not set the per-thread errno value on return.
229 lines
6.7 KiB
C
229 lines
6.7 KiB
C
/****************************************************************************
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* mm/mm_heap/mm_sem.c
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*
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* Copyright (C) 2007-2009, 2013, 2017 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <nuttx/semaphore.h>
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#include <nuttx/mm/mm.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* Define the following to enable semaphore state monitoring */
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//#define MONITOR_MM_SEMAPHORE 1
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#ifdef MONITOR_MM_SEMAPHORE
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# include <debug.h>
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# define msemerr _err
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# define msemwarn _warn
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# define mseminfo _info
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#else
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# ifdef CONFIG_CPP_HAVE_VARARGS
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# define msemerr(x...)
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# define msemwarn(x...)
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# define mseminfo(x...)
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# else
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# define msemerr (void)
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# define msemwarn (void)
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# define mseminfo (void)
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# endif
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#endif
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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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(void)nxsem_init(&heap->mm_semaphore, 0, 1);
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heap->mm_holder = -1;
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heap->mm_counts_held = 0;
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}
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/****************************************************************************
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* Name: mm_trysemaphore
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*
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* Description:
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* Try to take the MM mutex. This is called only from the OS in certain
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* conditions when it is necessary to have exclusive access to the memory
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* manager but it is impossible to wait on a semaphore (e.g., the idle
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* process when it performs its background memory cleanup).
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*
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****************************************************************************/
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int mm_trysemaphore(FAR struct mm_heap_s *heap)
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{
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pid_t my_pid = getpid();
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/* Do I already have the semaphore? */
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if (heap->mm_holder == my_pid)
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{
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/* Yes, just increment the number of references that I have */
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heap->mm_counts_held++;
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return OK;
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}
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else
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{
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/* Try to take the semaphore (perhaps waiting) */
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if (sem_trywait(&heap->mm_semaphore) != 0)
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{
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return ERROR;
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}
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/* We have it. Claim the stak and return */
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heap->mm_holder = my_pid;
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heap->mm_counts_held = 1;
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return OK;
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}
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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 is the normal action before all memory
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* management actions.
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*
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****************************************************************************/
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void mm_takesemaphore(FAR struct mm_heap_s *heap)
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{
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pid_t my_pid = getpid();
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/* Do I already have the semaphore? */
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if (heap->mm_holder == my_pid)
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{
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/* Yes, just increment the number of references that I have */
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heap->mm_counts_held++;
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}
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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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mseminfo("PID=%d taking\n", my_pid);
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do
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{
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ret = nxsem_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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DEBUGASSERT(ret == OK || ret == -EINTR);
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}
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while (ret == -EINTR);
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/* We have it (or some awful, unexpected error occurred). Claim
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* the semaphore and return.
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*/
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heap->mm_holder = my_pid;
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heap->mm_counts_held = 1;
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}
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mseminfo("Holder=%d count=%d\n", heap->mm_holder, heap->mm_counts_held);
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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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#if defined(CONFIG_DEBUG_ASSERTIONS) || \
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(defined(MONITOR_MM_SEMAPHORE) && defined(CONFIG_DEBUG_INFO))
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pid_t my_pid = getpid();
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#endif
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/* I better be holding at least one reference to the semaphore */
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DEBUGASSERT(heap->mm_holder == my_pid);
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/* Do I hold multiple references to the semphore */
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if (heap->mm_counts_held > 1)
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{
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/* Yes, just release one count and return */
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heap->mm_counts_held--;
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mseminfo("Holder=%d count=%d\n", heap->mm_holder,
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heap->mm_counts_held);
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}
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else
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{
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/* Nope, this is the last reference I have */
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mseminfo("PID=%d giving\n", my_pid);
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heap->mm_holder = -1;
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heap->mm_counts_held = 0;
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ASSERT(nxsem_post(&heap->mm_semaphore) == 0);
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}
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}
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