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Diffstat (limited to 'sys/contrib/dev/acpica/components/utilities/utlock.c')
| -rw-r--r-- | sys/contrib/dev/acpica/components/utilities/utlock.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/sys/contrib/dev/acpica/components/utilities/utlock.c b/sys/contrib/dev/acpica/components/utilities/utlock.c new file mode 100644 index 0000000..da933c2 --- /dev/null +++ b/sys/contrib/dev/acpica/components/utilities/utlock.c @@ -0,0 +1,204 @@ +/****************************************************************************** + * + * Module Name: utlock - Reader/Writer lock interfaces + * + *****************************************************************************/ + +/* + * Copyright (C) 2000 - 2013, Intel Corp. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions, and the following disclaimer, + * without modification. + * 2. Redistributions in binary form must reproduce at minimum a disclaimer + * substantially similar to the "NO WARRANTY" disclaimer below + * ("Disclaimer") and any redistribution must be conditioned upon + * including a substantially similar Disclaimer requirement for further + * binary redistribution. + * 3. Neither the names of the above-listed copyright holders nor the names + * of any contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * Alternatively, this software may be distributed under the terms of the + * GNU General Public License ("GPL") version 2 as published by the Free + * Software Foundation. + * + * NO WARRANTY + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING + * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGES. + */ + +#define __UTLOCK_C__ + +#include <contrib/dev/acpica/include/acpi.h> +#include <contrib/dev/acpica/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); +} |
