mirror of
https://github.com/reactos/reactos.git
synced 2024-09-05 18:26:53 +00:00
203 lines
5.8 KiB
C
203 lines
5.8 KiB
C
/******************************************************************************
|
|
*
|
|
* Module Name: utlock - Reader/Writer lock interfaces
|
|
*
|
|
*****************************************************************************/
|
|
|
|
/*
|
|
* Copyright (C) 2000 - 2018, Intel Corp.
|
|
* All rights reserved.
|
|
*
|
|
* 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,
|
|
* without modification.
|
|
* 2. Redistributions in binary form must reproduce at minimum a disclaimer
|
|
* substantially similar to the "NO WARRANTY" disclaimer below
|
|
* ("Disclaimer") and any redistribution must be conditioned upon
|
|
* including a substantially similar Disclaimer requirement for further
|
|
* binary redistribution.
|
|
* 3. Neither the names of the above-listed copyright holders nor the names
|
|
* of any contributors may be used to endorse or promote products derived
|
|
* from this software without specific prior written permission.
|
|
*
|
|
* Alternatively, this software may be distributed under the terms of the
|
|
* GNU General Public License ("GPL") version 2 as published by the Free
|
|
* Software Foundation.
|
|
*
|
|
* NO WARRANTY
|
|
* 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 MERCHANTIBILITY AND FITNESS FOR
|
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES.
|
|
*/
|
|
|
|
#include "acpi.h"
|
|
#include "accommon.h"
|
|
|
|
|
|
#define _COMPONENT ACPI_UTILITIES
|
|
ACPI_MODULE_NAME ("utlock")
|
|
|
|
|
|
/*******************************************************************************
|
|
*
|
|
* FUNCTION: AcpiUtCreateRwLock
|
|
* AcpiUtDeleteRwLock
|
|
*
|
|
* PARAMETERS: Lock - Pointer to a valid RW lock
|
|
*
|
|
* RETURN: Status
|
|
*
|
|
* DESCRIPTION: Reader/writer lock creation and deletion interfaces.
|
|
*
|
|
******************************************************************************/
|
|
|
|
ACPI_STATUS
|
|
AcpiUtCreateRwLock (
|
|
ACPI_RW_LOCK *Lock)
|
|
{
|
|
ACPI_STATUS Status;
|
|
|
|
|
|
Lock->NumReaders = 0;
|
|
Status = AcpiOsCreateMutex (&Lock->ReaderMutex);
|
|
if (ACPI_FAILURE (Status))
|
|
{
|
|
return (Status);
|
|
}
|
|
|
|
Status = AcpiOsCreateMutex (&Lock->WriterMutex);
|
|
return (Status);
|
|
}
|
|
|
|
|
|
void
|
|
AcpiUtDeleteRwLock (
|
|
ACPI_RW_LOCK *Lock)
|
|
{
|
|
|
|
AcpiOsDeleteMutex (Lock->ReaderMutex);
|
|
AcpiOsDeleteMutex (Lock->WriterMutex);
|
|
|
|
Lock->NumReaders = 0;
|
|
Lock->ReaderMutex = NULL;
|
|
Lock->WriterMutex = NULL;
|
|
}
|
|
|
|
|
|
/*******************************************************************************
|
|
*
|
|
* FUNCTION: AcpiUtAcquireReadLock
|
|
* AcpiUtReleaseReadLock
|
|
*
|
|
* PARAMETERS: Lock - Pointer to a valid RW lock
|
|
*
|
|
* RETURN: Status
|
|
*
|
|
* DESCRIPTION: Reader interfaces for reader/writer locks. On acquisition,
|
|
* only the first reader acquires the write mutex. On release,
|
|
* only the last reader releases the write mutex. Although this
|
|
* algorithm can in theory starve writers, this should not be a
|
|
* problem with ACPICA since the subsystem is infrequently used
|
|
* in comparison to (for example) an I/O system.
|
|
*
|
|
******************************************************************************/
|
|
|
|
ACPI_STATUS
|
|
AcpiUtAcquireReadLock (
|
|
ACPI_RW_LOCK *Lock)
|
|
{
|
|
ACPI_STATUS Status;
|
|
|
|
|
|
Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
|
|
if (ACPI_FAILURE (Status))
|
|
{
|
|
return (Status);
|
|
}
|
|
|
|
/* Acquire the write lock only for the first reader */
|
|
|
|
Lock->NumReaders++;
|
|
if (Lock->NumReaders == 1)
|
|
{
|
|
Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
|
|
}
|
|
|
|
AcpiOsReleaseMutex (Lock->ReaderMutex);
|
|
return (Status);
|
|
}
|
|
|
|
|
|
ACPI_STATUS
|
|
AcpiUtReleaseReadLock (
|
|
ACPI_RW_LOCK *Lock)
|
|
{
|
|
ACPI_STATUS Status;
|
|
|
|
|
|
Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
|
|
if (ACPI_FAILURE (Status))
|
|
{
|
|
return (Status);
|
|
}
|
|
|
|
/* Release the write lock only for the very last reader */
|
|
|
|
Lock->NumReaders--;
|
|
if (Lock->NumReaders == 0)
|
|
{
|
|
AcpiOsReleaseMutex (Lock->WriterMutex);
|
|
}
|
|
|
|
AcpiOsReleaseMutex (Lock->ReaderMutex);
|
|
return (Status);
|
|
}
|
|
|
|
|
|
/*******************************************************************************
|
|
*
|
|
* FUNCTION: AcpiUtAcquireWriteLock
|
|
* AcpiUtReleaseWriteLock
|
|
*
|
|
* PARAMETERS: Lock - Pointer to a valid RW lock
|
|
*
|
|
* RETURN: Status
|
|
*
|
|
* DESCRIPTION: Writer interfaces for reader/writer locks. Simply acquire or
|
|
* release the writer mutex associated with the lock. Acquisition
|
|
* of the lock is fully exclusive and will block all readers and
|
|
* writers until it is released.
|
|
*
|
|
******************************************************************************/
|
|
|
|
ACPI_STATUS
|
|
AcpiUtAcquireWriteLock (
|
|
ACPI_RW_LOCK *Lock)
|
|
{
|
|
ACPI_STATUS Status;
|
|
|
|
|
|
Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
|
|
return (Status);
|
|
}
|
|
|
|
|
|
void
|
|
AcpiUtReleaseWriteLock (
|
|
ACPI_RW_LOCK *Lock)
|
|
{
|
|
|
|
AcpiOsReleaseMutex (Lock->WriterMutex);
|
|
}
|