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c8100dc464
All tool/utility signons. Dual-license module header. Signed-off-by: Bob Moore <robert.moore@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
176 lines
5.6 KiB
C
176 lines
5.6 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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* Copyright (C) 2000 - 2016, Intel Corp.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions, and the following disclaimer,
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* without modification.
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* 2. Redistributions in binary form must reproduce at minimum a disclaimer
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* substantially similar to the "NO WARRANTY" disclaimer below
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* ("Disclaimer") and any redistribution must be conditioned upon
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* including a substantially similar Disclaimer requirement for further
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* binary redistribution.
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* 3. Neither the names of the above-listed copyright holders nor the names
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* of any contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* NO WARRANTY
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGES.
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*/
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#include <acpi/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: acpi_ut_create_rw_lock
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* acpi_ut_delete_rw_lock
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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 acpi_ut_create_rw_lock(struct acpi_rw_lock *lock)
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{
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acpi_status status;
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lock->num_readers = 0;
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status = acpi_os_create_mutex(&lock->reader_mutex);
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if (ACPI_FAILURE(status)) {
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return (status);
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}
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status = acpi_os_create_mutex(&lock->writer_mutex);
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return (status);
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}
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void acpi_ut_delete_rw_lock(struct acpi_rw_lock *lock)
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{
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acpi_os_delete_mutex(lock->reader_mutex);
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acpi_os_delete_mutex(lock->writer_mutex);
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lock->num_readers = 0;
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lock->reader_mutex = NULL;
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lock->writer_mutex = NULL;
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}
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/*******************************************************************************
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*
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* FUNCTION: acpi_ut_acquire_read_lock
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* acpi_ut_release_read_lock
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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 acpi_ut_acquire_read_lock(struct acpi_rw_lock *lock)
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{
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acpi_status status;
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status = acpi_os_acquire_mutex(lock->reader_mutex, ACPI_WAIT_FOREVER);
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if (ACPI_FAILURE(status)) {
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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->num_readers++;
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if (lock->num_readers == 1) {
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status =
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acpi_os_acquire_mutex(lock->writer_mutex,
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ACPI_WAIT_FOREVER);
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}
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acpi_os_release_mutex(lock->reader_mutex);
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return (status);
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}
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acpi_status acpi_ut_release_read_lock(struct acpi_rw_lock *lock)
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{
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acpi_status status;
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status = acpi_os_acquire_mutex(lock->reader_mutex, ACPI_WAIT_FOREVER);
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if (ACPI_FAILURE(status)) {
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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->num_readers--;
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if (lock->num_readers == 0) {
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acpi_os_release_mutex(lock->writer_mutex);
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}
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acpi_os_release_mutex(lock->reader_mutex);
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return (status);
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}
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/*******************************************************************************
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*
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* FUNCTION: acpi_ut_acquire_write_lock
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* acpi_ut_release_write_lock
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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 acpi_ut_acquire_write_lock(struct acpi_rw_lock *lock)
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{
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acpi_status status;
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status = acpi_os_acquire_mutex(lock->writer_mutex, ACPI_WAIT_FOREVER);
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return (status);
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}
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void acpi_ut_release_write_lock(struct acpi_rw_lock *lock)
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{
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acpi_os_release_mutex(lock->writer_mutex);
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}
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