sys/contrib/dev/acpica/source/components/utilities/utlock.c

   1 /******************************************************************************
   2  *
   3  * Module Name: utlock - Reader/Writer lock interfaces
   4  *
   5  *****************************************************************************/
   6
   7 /******************************************************************************
   8  *
   9  * 1. Copyright Notice
  10  *
  11  * Some or all of this work - Copyright (c) 1999 - 2018, Intel Corp.
  12  * All rights reserved.
  13  *
  14  * 2. License
  15  *
  16  * 2.1. This is your license from Intel Corp. under its intellectual property
  17  * rights. You may have additional license terms from the party that provided
  18  * you this software, covering your right to use that party's intellectual
  19  * property rights.
  20  *
  21  * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
  22  * copy of the source code appearing in this file ("Covered Code") an
  23  * irrevocable, perpetual, worldwide license under Intel's copyrights in the
  24  * base code distributed originally by Intel ("Original Intel Code") to copy,
  25  * make derivatives, distribute, use and display any portion of the Covered
  26  * Code in any form, with the right to sublicense such rights; and
  27  *
  28  * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
  29  * license (with the right to sublicense), under only those claims of Intel
  30  * patents that are infringed by the Original Intel Code, to make, use, sell,
  31  * offer to sell, and import the Covered Code and derivative works thereof
  32  * solely to the minimum extent necessary to exercise the above copyright
  33  * license, and in no event shall the patent license extend to any additions
  34  * to or modifications of the Original Intel Code. No other license or right
  35  * is granted directly or by implication, estoppel or otherwise;
  36  *
  37  * The above copyright and patent license is granted only if the following
  38  * conditions are met:
  39  *
  40  * 3. Conditions
  41  *
  42  * 3.1. Redistribution of Source with Rights to Further Distribute Source.
  43  * Redistribution of source code of any substantial portion of the Covered
  44  * Code or modification with rights to further distribute source must include
  45  * the above Copyright Notice, the above License, this list of Conditions,
  46  * and the following Disclaimer and Export Compliance provision. In addition,
  47  * Licensee must cause all Covered Code to which Licensee contributes to
  48  * contain a file documenting the changes Licensee made to create that Covered
  49  * Code and the date of any change. Licensee must include in that file the
  50  * documentation of any changes made by any predecessor Licensee. Licensee
  51  * must include a prominent statement that the modification is derived,
  52  * directly or indirectly, from Original Intel Code.
  53  *
  54  * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
  55  * Redistribution of source code of any substantial portion of the Covered
  56  * Code or modification without rights to further distribute source must
  57  * include the following Disclaimer and Export Compliance provision in the
  58  * documentation and/or other materials provided with distribution. In
  59  * addition, Licensee may not authorize further sublicense of source of any
  60  * portion of the Covered Code, and must include terms to the effect that the
  61  * license from Licensee to its licensee is limited to the intellectual
  62  * property embodied in the software Licensee provides to its licensee, and
  63  * not to intellectual property embodied in modifications its licensee may
  64  * make.
  65  *
  66  * 3.3. Redistribution of Executable. Redistribution in executable form of any
  67  * substantial portion of the Covered Code or modification must reproduce the
  68  * above Copyright Notice, and the following Disclaimer and Export Compliance
  69  * provision in the documentation and/or other materials provided with the
  70  * distribution.
  71  *
  72  * 3.4. Intel retains all right, title, and interest in and to the Original
  73  * Intel Code.
  74  *
  75  * 3.5. Neither the name Intel nor any other trademark owned or controlled by
  76  * Intel shall be used in advertising or otherwise to promote the sale, use or
  77  * other dealings in products derived from or relating to the Covered Code
  78  * without prior written authorization from Intel.
  79  *
  80  * 4. Disclaimer and Export Compliance
  81  *
  82  * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
  83  * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
  84  * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
  85  * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
  86  * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
  87  * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
  88  * PARTICULAR PURPOSE.
  89  *
  90  * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
  91  * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
  92  * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
  93  * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
  94  * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
  95  * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
  96  * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
  97  * LIMITED REMEDY.
  98  *
  99  * 4.3. Licensee shall not export, either directly or indirectly, any of this
 100  * software or system incorporating such software without first obtaining any
 101  * required license or other approval from the U. S. Department of Commerce or
 102  * any other agency or department of the United States Government. In the
 103  * event Licensee exports any such software from the United States or
 104  * re-exports any such software from a foreign destination, Licensee shall
 105  * ensure that the distribution and export/re-export of the software is in
 106  * compliance with all laws, regulations, orders, or other restrictions of the
 107  * U.S. Export Administration Regulations. Licensee agrees that neither it nor
 108  * any of its subsidiaries will export/re-export any technical data, process,
 109  * software, or service, directly or indirectly, to any country for which the
 110  * United States government or any agency thereof requires an export license,
 111  * other governmental approval, or letter of assurance, without first obtaining
 112  * such license, approval or letter.
 113  *
 114  *****************************************************************************
 115  *
 116  * Alternatively, you may choose to be licensed under the terms of the
 117  * following license:
 118  *
 119  * Redistribution and use in source and binary forms, with or without
 120  * modification, are permitted provided that the following conditions
 121  * are met:
 122  * 1. Redistributions of source code must retain the above copyright
 123  *    notice, this list of conditions, and the following disclaimer,
 124  *    without modification.
 125  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 126  *    substantially similar to the "NO WARRANTY" disclaimer below
 127  *    ("Disclaimer") and any redistribution must be conditioned upon
 128  *    including a substantially similar Disclaimer requirement for further
 129  *    binary redistribution.
 130  * 3. Neither the names of the above-listed copyright holders nor the names
 131  *    of any contributors may be used to endorse or promote products derived
 132  *    from this software without specific prior written permission.
 133  *
 134  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 135  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 136  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 137  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 138  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 139  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 140  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 141  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 142  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 143  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 144  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 145  *
 146  * Alternatively, you may choose to be licensed under the terms of the
 147  * GNU General Public License ("GPL") version 2 as published by the Free
 148  * Software Foundation.
 149  *
 150  *****************************************************************************/
 151
 152 #include "acpi.h"
 153 #include "accommon.h"
 154
 155
 156 #define _COMPONENT          ACPI_UTILITIES
 157         ACPI_MODULE_NAME    ("utlock")
 158
 159
 160 /*******************************************************************************
 161  *
 162  * FUNCTION:    AcpiUtCreateRwLock
 163  *              AcpiUtDeleteRwLock
 164  *
 165  * PARAMETERS:  Lock                - Pointer to a valid RW lock
 166  *
 167  * RETURN:      Status
 168  *
 169  * DESCRIPTION: Reader/writer lock creation and deletion interfaces.
 170  *
 171  ******************************************************************************/
 172
 173 ACPI_STATUS
 174 AcpiUtCreateRwLock (
 175     ACPI_RW_LOCK            *Lock)
 176 {
 177     ACPI_STATUS             Status;
 178
 179
 180     Lock->NumReaders = 0;
 181     Status = AcpiOsCreateMutex (&Lock->ReaderMutex);
 182     if (ACPI_FAILURE (Status))
 183     {
 184         return (Status);
 185     }
 186
 187     Status = AcpiOsCreateMutex (&Lock->WriterMutex);
 188     return (Status);
 189 }
 190
 191
 192 void
 193 AcpiUtDeleteRwLock (
 194     ACPI_RW_LOCK            *Lock)
 195 {
 196
 197     AcpiOsDeleteMutex (Lock->ReaderMutex);
 198     AcpiOsDeleteMutex (Lock->WriterMutex);
 199
 200     Lock->NumReaders = 0;
 201     Lock->ReaderMutex = NULL;
 202     Lock->WriterMutex = NULL;
 203 }
 204
 205
 206 /*******************************************************************************
 207  *
 208  * FUNCTION:    AcpiUtAcquireReadLock
 209  *              AcpiUtReleaseReadLock
 210  *
 211  * PARAMETERS:  Lock                - Pointer to a valid RW lock
 212  *
 213  * RETURN:      Status
 214  *
 215  * DESCRIPTION: Reader interfaces for reader/writer locks. On acquisition,
 216  *              only the first reader acquires the write mutex. On release,
 217  *              only the last reader releases the write mutex. Although this
 218  *              algorithm can in theory starve writers, this should not be a
 219  *              problem with ACPICA since the subsystem is infrequently used
 220  *              in comparison to (for example) an I/O system.
 221  *
 222  ******************************************************************************/
 223
 224 ACPI_STATUS
 225 AcpiUtAcquireReadLock (
 226     ACPI_RW_LOCK            *Lock)
 227 {
 228     ACPI_STATUS             Status;
 229
 230
 231     Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
 232     if (ACPI_FAILURE (Status))
 233     {
 234         return (Status);
 235     }
 236
 237     /* Acquire the write lock only for the first reader */
 238
 239     Lock->NumReaders++;
 240     if (Lock->NumReaders == 1)
 241     {
 242         Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
 243     }
 244
 245     AcpiOsReleaseMutex (Lock->ReaderMutex);
 246     return (Status);
 247 }
 248
 249
 250 ACPI_STATUS
 251 AcpiUtReleaseReadLock (
 252     ACPI_RW_LOCK            *Lock)
 253 {
 254     ACPI_STATUS             Status;
 255
 256
 257     Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER);
 258     if (ACPI_FAILURE (Status))
 259     {
 260         return (Status);
 261     }
 262
 263     /* Release the write lock only for the very last reader */
 264
 265     Lock->NumReaders--;
 266     if (Lock->NumReaders == 0)
 267     {
 268         AcpiOsReleaseMutex (Lock->WriterMutex);
 269     }
 270
 271     AcpiOsReleaseMutex (Lock->ReaderMutex);
 272     return (Status);
 273 }
 274
 275
 276 /*******************************************************************************
 277  *
 278  * FUNCTION:    AcpiUtAcquireWriteLock
 279  *              AcpiUtReleaseWriteLock
 280  *
 281  * PARAMETERS:  Lock                - Pointer to a valid RW lock
 282  *
 283  * RETURN:      Status
 284  *
 285  * DESCRIPTION: Writer interfaces for reader/writer locks. Simply acquire or
 286  *              release the writer mutex associated with the lock. Acquisition
 287  *              of the lock is fully exclusive and will block all readers and
 288  *              writers until it is released.
 289  *
 290  ******************************************************************************/
 291
 292 ACPI_STATUS
 293 AcpiUtAcquireWriteLock (
 294     ACPI_RW_LOCK            *Lock)
 295 {
 296     ACPI_STATUS             Status;
 297
 298
 299     Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER);
 300     return (Status);
 301 }
 302
 303
 304 void
 305 AcpiUtReleaseWriteLock (
 306     ACPI_RW_LOCK            *Lock)
 307 {
 308
 309     AcpiOsReleaseMutex (Lock->WriterMutex);
 310 }