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 - 2016, 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 #include "acpi.h" 117 #include "accommon.h" 118 119 120 #define _COMPONENT ACPI_UTILITIES 121 ACPI_MODULE_NAME ("utlock") 122 123 124 /******************************************************************************* 125 * 126 * FUNCTION: AcpiUtCreateRwLock 127 * AcpiUtDeleteRwLock 128 * 129 * PARAMETERS: Lock - Pointer to a valid RW lock 130 * 131 * RETURN: Status 132 * 133 * DESCRIPTION: Reader/writer lock creation and deletion interfaces. 134 * 135 ******************************************************************************/ 136 137 ACPI_STATUS 138 AcpiUtCreateRwLock ( 139 ACPI_RW_LOCK *Lock) 140 { 141 ACPI_STATUS Status; 142 143 144 Lock->NumReaders = 0; 145 Status = AcpiOsCreateMutex (&Lock->ReaderMutex); 146 if (ACPI_FAILURE (Status)) 147 { 148 return (Status); 149 } 150 151 Status = AcpiOsCreateMutex (&Lock->WriterMutex); 152 return (Status); 153 } 154 155 156 void 157 AcpiUtDeleteRwLock ( 158 ACPI_RW_LOCK *Lock) 159 { 160 161 AcpiOsDeleteMutex (Lock->ReaderMutex); 162 AcpiOsDeleteMutex (Lock->WriterMutex); 163 164 Lock->NumReaders = 0; 165 Lock->ReaderMutex = NULL; 166 Lock->WriterMutex = NULL; 167 } 168 169 170 /******************************************************************************* 171 * 172 * FUNCTION: AcpiUtAcquireReadLock 173 * AcpiUtReleaseReadLock 174 * 175 * PARAMETERS: Lock - Pointer to a valid RW lock 176 * 177 * RETURN: Status 178 * 179 * DESCRIPTION: Reader interfaces for reader/writer locks. On acquisition, 180 * only the first reader acquires the write mutex. On release, 181 * only the last reader releases the write mutex. Although this 182 * algorithm can in theory starve writers, this should not be a 183 * problem with ACPICA since the subsystem is infrequently used 184 * in comparison to (for example) an I/O system. 185 * 186 ******************************************************************************/ 187 188 ACPI_STATUS 189 AcpiUtAcquireReadLock ( 190 ACPI_RW_LOCK *Lock) 191 { 192 ACPI_STATUS Status; 193 194 195 Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER); 196 if (ACPI_FAILURE (Status)) 197 { 198 return (Status); 199 } 200 201 /* Acquire the write lock only for the first reader */ 202 203 Lock->NumReaders++; 204 if (Lock->NumReaders == 1) 205 { 206 Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER); 207 } 208 209 AcpiOsReleaseMutex (Lock->ReaderMutex); 210 return (Status); 211 } 212 213 214 ACPI_STATUS 215 AcpiUtReleaseReadLock ( 216 ACPI_RW_LOCK *Lock) 217 { 218 ACPI_STATUS Status; 219 220 221 Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER); 222 if (ACPI_FAILURE (Status)) 223 { 224 return (Status); 225 } 226 227 /* Release the write lock only for the very last reader */ 228 229 Lock->NumReaders--; 230 if (Lock->NumReaders == 0) 231 { 232 AcpiOsReleaseMutex (Lock->WriterMutex); 233 } 234 235 AcpiOsReleaseMutex (Lock->ReaderMutex); 236 return (Status); 237 } 238 239 240 /******************************************************************************* 241 * 242 * FUNCTION: AcpiUtAcquireWriteLock 243 * AcpiUtReleaseWriteLock 244 * 245 * PARAMETERS: Lock - Pointer to a valid RW lock 246 * 247 * RETURN: Status 248 * 249 * DESCRIPTION: Writer interfaces for reader/writer locks. Simply acquire or 250 * release the writer mutex associated with the lock. Acquisition 251 * of the lock is fully exclusive and will block all readers and 252 * writers until it is released. 253 * 254 ******************************************************************************/ 255 256 ACPI_STATUS 257 AcpiUtAcquireWriteLock ( 258 ACPI_RW_LOCK *Lock) 259 { 260 ACPI_STATUS Status; 261 262 263 Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER); 264 return (Status); 265 } 266 267 268 void 269 AcpiUtReleaseWriteLock ( 270 ACPI_RW_LOCK *Lock) 271 { 272 273 AcpiOsReleaseMutex (Lock->WriterMutex); 274 } 275