utlock.c revision aa2aa9a662539940ddbc8610da5a3a874ebd7503
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Module Name: utlock - Reader/Writer lock interfaces
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *****************************************************************************/
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 1. Copyright Notice
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Some or all of this work - Copyright (c) 1999 - 2009, Intel Corp.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * All rights reserved.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 2. License
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 2.1. This is your license from Intel Corp. under its intellectual property
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * rights. You may have additional license terms from the party that provided
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * you this software, covering your right to use that party's intellectual
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * property rights.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * copy of the source code appearing in this file ("Covered Code") an
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * irrevocable, perpetual, worldwide license under Intel's copyrights in the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * base code distributed originally by Intel ("Original Intel Code") to copy,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * make derivatives, distribute, use and display any portion of the Covered
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Code in any form, with the right to sublicense such rights; and
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * license (with the right to sublicense), under only those claims of Intel
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * patents that are infringed by the Original Intel Code, to make, use, sell,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * offer to sell, and import the Covered Code and derivative works thereof
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * solely to the minimum extent necessary to exercise the above copyright
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * license, and in no event shall the patent license extend to any additions
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * to or modifications of the Original Intel Code. No other license or right
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * is granted directly or by implication, estoppel or otherwise;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * The above copyright and patent license is granted only if the following
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * conditions are met:
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 3. Conditions
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 3.1. Redistribution of Source with Rights to Further Distribute Source.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Redistribution of source code of any substantial portion of the Covered
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Code or modification with rights to further distribute source must include
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * the above Copyright Notice, the above License, this list of Conditions,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * and the following Disclaimer and Export Compliance provision. In addition,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Licensee must cause all Covered Code to which Licensee contributes to
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * contain a file documenting the changes Licensee made to create that Covered
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Code and the date of any change. Licensee must include in that file the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * documentation of any changes made by any predecessor Licensee. Licensee
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * must include a prominent statement that the modification is derived,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * directly or indirectly, from Original Intel Code.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Redistribution of source code of any substantial portion of the Covered
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Code or modification without rights to further distribute source must
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * include the following Disclaimer and Export Compliance provision in the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * documentation and/or other materials provided with distribution. In
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * addition, Licensee may not authorize further sublicense of source of any
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * portion of the Covered Code, and must include terms to the effect that the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * license from Licensee to its licensee is limited to the intellectual
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * property embodied in the software Licensee provides to its licensee, and
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * not to intellectual property embodied in modifications its licensee may
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 3.3. Redistribution of Executable. Redistribution in executable form of any
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * substantial portion of the Covered Code or modification must reproduce the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * above Copyright Notice, and the following Disclaimer and Export Compliance
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * provision in the documentation and/or other materials provided with the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * distribution.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 3.4. Intel retains all right, title, and interest in and to the Original
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Intel Code.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 3.5. Neither the name Intel nor any other trademark owned or controlled by
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Intel shall be used in advertising or otherwise to promote the sale, use or
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * other dealings in products derived from or relating to the Covered Code
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * without prior written authorization from Intel.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 4. Disclaimer and Export Compliance
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * PARTICULAR PURPOSE.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * LIMITED REMEDY.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * 4.3. Licensee shall not export, either directly or indirectly, any of this
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * software or system incorporating such software without first obtaining any
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * required license or other approval from the U. S. Department of Commerce or
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * any other agency or department of the United States Government. In the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * event Licensee exports any such software from the United States or
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * re-exports any such software from a foreign destination, Licensee shall
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * ensure that the distribution and export/re-export of the software is in
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * compliance with all laws, regulations, orders, or other restrictions of the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * U.S. Export Administration Regulations. Licensee agrees that neither it nor
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * any of its subsidiaries will export/re-export any technical data, process,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * software, or service, directly or indirectly, to any country for which the
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * United States government or any agency thereof requires an export license,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * other governmental approval, or letter of assurance, without first obtaining
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * such license, approval or letter.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *****************************************************************************/
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/*******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * FUNCTION: AcpiUtCreateRwLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * AcpiUtDeleteRwLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * PARAMETERS: Lock - Pointer to a valid RW lock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * RETURN: Status
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * DESCRIPTION: Reader/writer lock creation and deletion interfaces.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers ******************************************************************************/
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/*******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * FUNCTION: AcpiUtAcquireReadLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * AcpiUtReleaseReadLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * PARAMETERS: Lock - Pointer to a valid RW lock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * RETURN: Status
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * DESCRIPTION: Reader interfaces for reader/writer locks. On acquisition,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * only the first reader acquires the write mutex. On release,
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * only the last reader releases the write mutex. Although this
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * algorithm can in theory starve writers, this should not be a
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * problem with ACPICA since the subsystem is infrequently used
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * in comparison to (for example) an I/O system.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers ******************************************************************************/
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers /* Acquire the write lock only for the first reader */
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers /* Release the write lock only for the very last reader */
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/*******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * FUNCTION: AcpiUtAcquireWriteLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * AcpiUtReleaseWriteLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * PARAMETERS: Lock - Pointer to a valid RW lock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * RETURN: Status
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * DESCRIPTION: Writer interfaces for reader/writer locks. Simply acquire or
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * release the writer mutex associated with the lock. Acquisition
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * of the lock is fully exclusive and will block all readers and
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * writers until it is released.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers ******************************************************************************/