acpica/utilities/utlock.c

aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * Module Name: utlock - Reader/Writer lock interfaces
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *****************************************************************************/
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross/*
7b1019a6d29ccb7999dc76cba3dde1c627e8e609Jerry Jelinek * Copyright (C) 2000 - 2016, Intel Corp.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * All rights reserved.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * Redistribution and use in source and binary forms, with or without
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * modification, are permitted provided that the following conditions
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * are met:
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * 1. Redistributions of source code must retain the above copyright
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *    notice, this list of conditions, and the following disclaimer,
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *    without modification.
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * 2. Redistributions in binary form must reproduce at minimum a disclaimer
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *    substantially similar to the "NO WARRANTY" disclaimer below
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *    ("Disclaimer") and any redistribution must be conditioned upon
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *    including a substantially similar Disclaimer requirement for further
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *    binary redistribution.
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * 3. Neither the names of the above-listed copyright holders nor the names
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *    of any contributors may be used to endorse or promote products derived
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *    from this software without specific prior written permission.
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * Alternatively, this software may be distributed under the terms of the
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * GNU General Public License ("GPL") version 2 as published by the Free
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * Software Foundation.
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross *
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * NO WARRANTY
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross * POSSIBILITY OF SUCH DAMAGES.
26f3cdf03f1adcc98f6d3d99843ee71e9229a8c0Gordon Ross */
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers#include "acpi.h"
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers#include "accommon.h"
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers#define _COMPONENT          ACPI_UTILITIES
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers        ACPI_MODULE_NAME    ("utlock")
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/*******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * FUNCTION:    AcpiUtCreateRwLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *              AcpiUtDeleteRwLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * PARAMETERS:  Lock                - Pointer to a valid RW lock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * RETURN:      Status
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * DESCRIPTION: Reader/writer lock creation and deletion interfaces.
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers ******************************************************************************/
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersACPI_STATUS
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersAcpiUtCreateRwLock (
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_RW_LOCK            *Lock)
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers{
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_STATUS             Status;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Lock->NumReaders = 0;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Status = AcpiOsCreateMutex (&Lock->ReaderMutex);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    if (ACPI_FAILURE (Status))
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    {
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers        return (Status);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    }
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Status = AcpiOsCreateMutex (&Lock->WriterMutex);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    return (Status);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers}
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myersvoid
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersAcpiUtDeleteRwLock (
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_RW_LOCK            *Lock)
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers{
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    AcpiOsDeleteMutex (Lock->ReaderMutex);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    AcpiOsDeleteMutex (Lock->WriterMutex);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Lock->NumReaders = 0;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Lock->ReaderMutex = NULL;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Lock->WriterMutex = NULL;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers}
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/*******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * FUNCTION:    AcpiUtAcquireReadLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *              AcpiUtReleaseReadLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * PARAMETERS:  Lock                - Pointer to a valid RW lock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * RETURN:      Status
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
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 ******************************************************************************/
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersACPI_STATUS
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersAcpiUtAcquireReadLock (
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_RW_LOCK            *Lock)
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers{
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_STATUS             Status;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    if (ACPI_FAILURE (Status))
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    {
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers        return (Status);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    }
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    /* Acquire the write lock only for the first reader */
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Lock->NumReaders++;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    if (Lock->NumReaders == 1)
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    {
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers        Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    }
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    AcpiOsReleaseMutex (Lock->ReaderMutex);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    return (Status);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers}
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersACPI_STATUS
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersAcpiUtReleaseReadLock (
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_RW_LOCK            *Lock)
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers{
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_STATUS             Status;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    if (ACPI_FAILURE (Status))
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    {
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers        return (Status);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    }
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    /* Release the write lock only for the very last reader */
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Lock->NumReaders--;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    if (Lock->NumReaders == 0)
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    {
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers        AcpiOsReleaseMutex (Lock->WriterMutex);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    }
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    AcpiOsReleaseMutex (Lock->ReaderMutex);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    return (Status);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers}
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers/*******************************************************************************
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * FUNCTION:    AcpiUtAcquireWriteLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *              AcpiUtReleaseWriteLock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * PARAMETERS:  Lock                - Pointer to a valid RW lock
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers * RETURN:      Status
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers *
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 *
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers ******************************************************************************/
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersACPI_STATUS
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersAcpiUtAcquireWriteLock (
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_RW_LOCK            *Lock)
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers{
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_STATUS             Status;
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    return (Status);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers}
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myersvoid
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana MyersAcpiUtReleaseWriteLock (
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    ACPI_RW_LOCK            *Lock)
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers{
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers    AcpiOsReleaseMutex (Lock->WriterMutex);
aa2aa9a662539940ddbc8610da5a3a874ebd7503Dana Myers}