6a3c2aded6
* Simplify EINTR/ECANCEL error handling 1. Add semaphore uninterruptible wait function 2 .Replace semaphore wait loop with a single uninterruptible wait 3. Replace all sem_xxx to nxsem_xxx * Unify the void cast usage 1. Remove void cast for function because many place ignore the returned value witout cast 2. Replace void cast for variable with UNUSED macro
162 lines
4.8 KiB
C
162 lines
4.8 KiB
C
/****************************************************************************
|
|
* libs/libc/misc/lib_filesem.c
|
|
*
|
|
* Copyright (C) 2007, 2009, 2011, 2017 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 <nuttx/config.h>
|
|
|
|
#include <sys/types.h>
|
|
#include <unistd.h>
|
|
#include <semaphore.h>
|
|
#include <errno.h>
|
|
#include <assert.h>
|
|
|
|
#include <nuttx/semaphore.h>
|
|
#include <nuttx/fs/fs.h>
|
|
|
|
#ifdef CONFIG_SMP
|
|
# include <nuttx/irq.h>
|
|
#endif
|
|
|
|
#include "libc.h"
|
|
|
|
#ifndef CONFIG_STDIO_DISABLE_BUFFERING
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* lib_sem_initialize
|
|
****************************************************************************/
|
|
|
|
void lib_sem_initialize(FAR struct file_struct *stream)
|
|
{
|
|
/* Initialize the LIB semaphore to one (to support one-at-a-time access
|
|
* to private data sets.
|
|
*/
|
|
|
|
nxsem_init(&stream->fs_sem, 0, 1);
|
|
|
|
stream->fs_holder = -1;
|
|
stream->fs_counts = 0;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* lib_take_semaphore
|
|
****************************************************************************/
|
|
|
|
void lib_take_semaphore(FAR struct file_struct *stream)
|
|
{
|
|
#ifdef CONFIG_SMP
|
|
irqstate_t flags = enter_critical_section();
|
|
#endif
|
|
|
|
pid_t my_pid = getpid();
|
|
int ret;
|
|
|
|
/* Do I already have the semaphore? */
|
|
|
|
if (stream->fs_holder == my_pid)
|
|
{
|
|
/* Yes, just increment the number of references that I have */
|
|
|
|
stream->fs_counts++;
|
|
}
|
|
else
|
|
{
|
|
/* Take the semaphore (perhaps waiting) */
|
|
|
|
while ((ret = _SEM_WAIT(&stream->fs_sem)) < 0)
|
|
{
|
|
/* The only case that an error should occr here is if the wait
|
|
* was awakened by a signal.
|
|
*/
|
|
|
|
DEBUGASSERT(_SEM_ERRNO(ret) == EINTR || _SEM_ERRNO(ret) == ECANCELED);
|
|
UNUSED(ret);
|
|
}
|
|
|
|
/* We have it. Claim the stak and return */
|
|
|
|
stream->fs_holder = my_pid;
|
|
stream->fs_counts = 1;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
leave_critical_section(flags);
|
|
#endif
|
|
}
|
|
|
|
/****************************************************************************
|
|
* lib_give_semaphore
|
|
****************************************************************************/
|
|
|
|
void lib_give_semaphore(FAR struct file_struct *stream)
|
|
{
|
|
#ifdef CONFIG_SMP
|
|
irqstate_t flags = enter_critical_section();
|
|
#endif
|
|
|
|
/* I better be holding at least one reference to the semaphore */
|
|
|
|
DEBUGASSERT(stream->fs_holder == getpid());
|
|
|
|
/* Do I hold multiple references to the semphore */
|
|
|
|
if (stream->fs_counts > 1)
|
|
{
|
|
/* Yes, just release one count and return */
|
|
|
|
stream->fs_counts--;
|
|
}
|
|
else
|
|
{
|
|
/* Nope, this is the last reference I have */
|
|
|
|
stream->fs_holder = -1;
|
|
stream->fs_counts = 0;
|
|
DEBUGVERIFY(_SEM_POST(&stream->fs_sem));
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
leave_critical_section(flags);
|
|
#endif
|
|
}
|
|
|
|
#endif /* CONFIG_STDIO_DISABLE_BUFFERING */
|