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 } 311