278 lines
10 KiB
C
278 lines
10 KiB
C
/******************************************************************************
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*
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* Module Name: utlock - Reader/Writer lock interfaces
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*
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*****************************************************************************/
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/******************************************************************************
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*
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* 1. Copyright Notice
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*
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* Some or all of this work - Copyright (c) 1999 - 2010, Intel Corp.
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* All rights reserved.
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*
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* 2. License
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*
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* 2.1. This is your license from Intel Corp. under its intellectual property
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* rights. You may have additional license terms from the party that provided
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* you this software, covering your right to use that party's intellectual
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* property rights.
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*
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* 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
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* copy of the source code appearing in this file ("Covered Code") an
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* irrevocable, perpetual, worldwide license under Intel's copyrights in the
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* base code distributed originally by Intel ("Original Intel Code") to copy,
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* make derivatives, distribute, use and display any portion of the Covered
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* Code in any form, with the right to sublicense such rights; and
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*
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* 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
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* license (with the right to sublicense), under only those claims of Intel
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* patents that are infringed by the Original Intel Code, to make, use, sell,
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* offer to sell, and import the Covered Code and derivative works thereof
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* solely to the minimum extent necessary to exercise the above copyright
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* license, and in no event shall the patent license extend to any additions
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* to or modifications of the Original Intel Code. No other license or right
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* is granted directly or by implication, estoppel or otherwise;
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*
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* The above copyright and patent license is granted only if the following
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* conditions are met:
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*
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* 3. Conditions
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*
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* 3.1. Redistribution of Source with Rights to Further Distribute Source.
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* Redistribution of source code of any substantial portion of the Covered
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* Code or modification with rights to further distribute source must include
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* the above Copyright Notice, the above License, this list of Conditions,
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* and the following Disclaimer and Export Compliance provision. In addition,
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* Licensee must cause all Covered Code to which Licensee contributes to
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* contain a file documenting the changes Licensee made to create that Covered
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* Code and the date of any change. Licensee must include in that file the
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* documentation of any changes made by any predecessor Licensee. Licensee
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* must include a prominent statement that the modification is derived,
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* directly or indirectly, from Original Intel Code.
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*
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* 3.2. Redistribution of Source with no Rights to Further Distribute Source.
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* Redistribution of source code of any substantial portion of the Covered
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* Code or modification without rights to further distribute source must
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* include the following Disclaimer and Export Compliance provision in the
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* documentation and/or other materials provided with distribution. In
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* addition, Licensee may not authorize further sublicense of source of any
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* portion of the Covered Code, and must include terms to the effect that the
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* license from Licensee to its licensee is limited to the intellectual
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* property embodied in the software Licensee provides to its licensee, and
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* not to intellectual property embodied in modifications its licensee may
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* make.
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*
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* 3.3. Redistribution of Executable. Redistribution in executable form of any
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* substantial portion of the Covered Code or modification must reproduce the
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* above Copyright Notice, and the following Disclaimer and Export Compliance
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* provision in the documentation and/or other materials provided with the
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* distribution.
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*
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* 3.4. Intel retains all right, title, and interest in and to the Original
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* Intel Code.
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*
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* 3.5. Neither the name Intel nor any other trademark owned or controlled by
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* Intel shall be used in advertising or otherwise to promote the sale, use or
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* other dealings in products derived from or relating to the Covered Code
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* without prior written authorization from Intel.
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*
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* 4. Disclaimer and Export Compliance
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*
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* 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
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* HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
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* IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
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* INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
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* UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
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* IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
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* PARTICULAR PURPOSE.
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*
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* 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
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* OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
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* COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
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* SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
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* CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
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* HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
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* SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
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* LIMITED REMEDY.
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*
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* 4.3. Licensee shall not export, either directly or indirectly, any of this
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* software or system incorporating such software without first obtaining any
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* required license or other approval from the U. S. Department of Commerce or
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* any other agency or department of the United States Government. In the
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* event Licensee exports any such software from the United States or
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* re-exports any such software from a foreign destination, Licensee shall
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* ensure that the distribution and export/re-export of the software is in
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* compliance with all laws, regulations, orders, or other restrictions of the
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* U.S. Export Administration Regulations. Licensee agrees that neither it nor
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* any of its subsidiaries will export/re-export any technical data, process,
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* software, or service, directly or indirectly, to any country for which the
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* United States government or any agency thereof requires an export license,
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* other governmental approval, or letter of assurance, without first obtaining
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* such license, approval or letter.
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*
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*****************************************************************************/
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#define __UTLOCK_C__
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#include "acpi.h"
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#include "accommon.h"
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#define _COMPONENT ACPI_UTILITIES
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ACPI_MODULE_NAME ("utlock")
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/*******************************************************************************
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*
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* FUNCTION: AcpiUtCreateRwLock
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* AcpiUtDeleteRwLock
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*
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* PARAMETERS: Lock - Pointer to a valid RW lock
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*
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* RETURN: Status
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*
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* DESCRIPTION: Reader/writer lock creation and deletion interfaces.
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*
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******************************************************************************/
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ACPI_STATUS
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AcpiUtCreateRwLock (
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ACPI_RW_LOCK *Lock)
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{
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ACPI_STATUS Status;
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Lock->NumReaders = 0;
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Status = AcpiOsCreateMutex (&Lock->ReaderMutex);
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if (ACPI_FAILURE (Status))
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{
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return (Status);
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}
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Status = AcpiOsCreateMutex (&Lock->WriterMutex);
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return (Status);
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}
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void
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AcpiUtDeleteRwLock (
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ACPI_RW_LOCK *Lock)
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{
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AcpiOsDeleteMutex (Lock->ReaderMutex);
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AcpiOsDeleteMutex (Lock->WriterMutex);
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Lock->NumReaders = 0;
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Lock->ReaderMutex = NULL;
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Lock->WriterMutex = NULL;
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}
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/*******************************************************************************
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*
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* FUNCTION: AcpiUtAcquireReadLock
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* AcpiUtReleaseReadLock
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*
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* PARAMETERS: Lock - Pointer to a valid RW lock
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*
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* RETURN: Status
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*
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* DESCRIPTION: Reader interfaces for reader/writer locks. On acquisition,
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* only the first reader acquires the write mutex. On release,
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* only the last reader releases the write mutex. Although this
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* algorithm can in theory starve writers, this should not be a
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* problem with ACPICA since the subsystem is infrequently used
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* in comparison to (for example) an I/O system.
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*
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******************************************************************************/
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ACPI_STATUS
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AcpiUtAcquireReadLock (
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ACPI_RW_LOCK *Lock)
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{
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ACPI_STATUS Status;
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Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
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if (ACPI_FAILURE (Status))
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{
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return (Status);
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}
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/* Acquire the write lock only for the first reader */
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Lock->NumReaders++;
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if (Lock->NumReaders == 1)
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{
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Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
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}
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AcpiOsReleaseMutex (Lock->ReaderMutex);
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return (Status);
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}
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ACPI_STATUS
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AcpiUtReleaseReadLock (
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ACPI_RW_LOCK *Lock)
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{
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ACPI_STATUS Status;
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Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
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if (ACPI_FAILURE (Status))
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{
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return (Status);
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}
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/* Release the write lock only for the very last reader */
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Lock->NumReaders--;
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if (Lock->NumReaders == 0)
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{
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AcpiOsReleaseMutex (Lock->WriterMutex);
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}
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AcpiOsReleaseMutex (Lock->ReaderMutex);
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return (Status);
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}
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/*******************************************************************************
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*
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* FUNCTION: AcpiUtAcquireWriteLock
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* AcpiUtReleaseWriteLock
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*
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* PARAMETERS: Lock - Pointer to a valid RW lock
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*
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* RETURN: Status
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*
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* DESCRIPTION: Writer interfaces for reader/writer locks. Simply acquire or
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* release the writer mutex associated with the lock. Acquisition
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* of the lock is fully exclusive and will block all readers and
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* writers until it is released.
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*
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******************************************************************************/
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ACPI_STATUS
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AcpiUtAcquireWriteLock (
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ACPI_RW_LOCK *Lock)
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{
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ACPI_STATUS Status;
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Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
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return (Status);
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}
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void
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AcpiUtReleaseWriteLock (
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ACPI_RW_LOCK *Lock)
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{
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AcpiOsReleaseMutex (Lock->WriterMutex);
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}
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