/******************************************************************************
*
* Module Name: utlock - Reader/Writer lock interfaces
*
*****************************************************************************/
/******************************************************************************
*
* 1. Copyright Notice
*
* Some or all of this work - Copyright (c) 1999 - 2011, Intel Corp.
* All rights reserved.
*
* 2. License
*
* 2.1. This is your license from Intel Corp. under its intellectual property
* rights. You may have additional license terms from the party that provided
* you this software, covering your right to use that party's intellectual
* property rights.
*
* 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
* copy of the source code appearing in this file ("Covered Code") an
* irrevocable, perpetual, worldwide license under Intel's copyrights in the
* base code distributed originally by Intel ("Original Intel Code") to copy,
* make derivatives, distribute, use and display any portion of the Covered
* Code in any form, with the right to sublicense such rights; and
*
* 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
* license (with the right to sublicense), under only those claims of Intel
* patents that are infringed by the Original Intel Code, to make, use, sell,
* offer to sell, and import the Covered Code and derivative works thereof
* solely to the minimum extent necessary to exercise the above copyright
* license, and in no event shall the patent license extend to any additions
* to or modifications of the Original Intel Code. No other license or right
* is granted directly or by implication, estoppel or otherwise;
*
* The above copyright and patent license is granted only if the following
* conditions are met:
*
* 3. Conditions
*
* 3.1. Redistribution of Source with Rights to Further Distribute Source.
* Redistribution of source code of any substantial portion of the Covered
* Code or modification with rights to further distribute source must include
* the above Copyright Notice, the above License, this list of Conditions,
* and the following Disclaimer and Export Compliance provision. In addition,
* Licensee must cause all Covered Code to which Licensee contributes to
* contain a file documenting the changes Licensee made to create that Covered
* Code and the date of any change. Licensee must include in that file the
* documentation of any changes made by any predecessor Licensee. Licensee
* must include a prominent statement that the modification is derived,
* directly or indirectly, from Original Intel Code.
*
* 3.2. Redistribution of Source with no Rights to Further Distribute Source.
* Redistribution of source code of any substantial portion of the Covered
* Code or modification without rights to further distribute source must
* include the following Disclaimer and Export Compliance provision in the
* documentation and/or other materials provided with distribution. In
* addition, Licensee may not authorize further sublicense of source of any
* portion of the Covered Code, and must include terms to the effect that the
* license from Licensee to its licensee is limited to the intellectual
* property embodied in the software Licensee provides to its licensee, and
* not to intellectual property embodied in modifications its licensee may
* make.
*
* 3.3. Redistribution of Executable. Redistribution in executable form of any
* substantial portion of the Covered Code or modification must reproduce the
* above Copyright Notice, and the following Disclaimer and Export Compliance
* provision in the documentation and/or other materials provided with the
* distribution.
*
* 3.4. Intel retains all right, title, and interest in and to the Original
* Intel Code.
*
* 3.5. Neither the name Intel nor any other trademark owned or controlled by
* Intel shall be used in advertising or otherwise to promote the sale, use or
* other dealings in products derived from or relating to the Covered Code
* without prior written authorization from Intel.
*
* 4. Disclaimer and Export Compliance
*
* 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
* HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
* IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
* INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
* UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
* IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
* PARTICULAR PURPOSE.
*
* 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
* OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
* COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
* SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
* CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
* HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
* SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
* LIMITED REMEDY.
*
* 4.3. Licensee shall not export, either directly or indirectly, any of this
* software or system incorporating such software without first obtaining any
* required license or other approval from the U. S. Department of Commerce or
* any other agency or department of the United States Government. In the
* event Licensee exports any such software from the United States or
* re-exports any such software from a foreign destination, Licensee shall
* ensure that the distribution and export/re-export of the software is in
* compliance with all laws, regulations, orders, or other restrictions of the
* U.S. Export Administration Regulations. Licensee agrees that neither it nor
* any of its subsidiaries will export/re-export any technical data, process,
* software, or service, directly or indirectly, to any country for which the
* United States government or any agency thereof requires an export license,
* other governmental approval, or letter of assurance, without first obtaining
* such license, approval or letter.
*
*****************************************************************************/
#define __UTLOCK_C__
#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);
}