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 - 2009, 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 #define __UTLOCK_C__ 117 118 #include "acpi.h" 119 #include "accommon.h" 120 121 122 #define _COMPONENT ACPI_UTILITIES 123 ACPI_MODULE_NAME ("utlock") 124 125 126 /******************************************************************************* 127 * 128 * FUNCTION: AcpiUtCreateRwLock 129 * AcpiUtDeleteRwLock 130 * 131 * PARAMETERS: Lock - Pointer to a valid RW lock 132 * 133 * RETURN: Status 134 * 135 * DESCRIPTION: Reader/writer lock creation and deletion interfaces. 136 * 137 ******************************************************************************/ 138 139 ACPI_STATUS 140 AcpiUtCreateRwLock ( 141 ACPI_RW_LOCK *Lock) 142 { 143 ACPI_STATUS Status; 144 145 146 Lock->NumReaders = 0; 147 Status = AcpiOsCreateMutex (&Lock->ReaderMutex); 148 if (ACPI_FAILURE (Status)) 149 { 150 return (Status); 151 } 152 153 Status = AcpiOsCreateMutex (&Lock->WriterMutex); 154 return (Status); 155 } 156 157 158 void 159 AcpiUtDeleteRwLock ( 160 ACPI_RW_LOCK *Lock) 161 { 162 163 AcpiOsDeleteMutex (Lock->ReaderMutex); 164 AcpiOsDeleteMutex (Lock->WriterMutex); 165 166 Lock->NumReaders = 0; 167 Lock->ReaderMutex = NULL; 168 Lock->WriterMutex = NULL; 169 } 170 171 172 /******************************************************************************* 173 * 174 * FUNCTION: AcpiUtAcquireReadLock 175 * AcpiUtReleaseReadLock 176 * 177 * PARAMETERS: Lock - Pointer to a valid RW lock 178 * 179 * RETURN: Status 180 * 181 * DESCRIPTION: Reader interfaces for reader/writer locks. On acquisition, 182 * only the first reader acquires the write mutex. On release, 183 * only the last reader releases the write mutex. Although this 184 * algorithm can in theory starve writers, this should not be a 185 * problem with ACPICA since the subsystem is infrequently used 186 * in comparison to (for example) an I/O system. 187 * 188 ******************************************************************************/ 189 190 ACPI_STATUS 191 AcpiUtAcquireReadLock ( 192 ACPI_RW_LOCK *Lock) 193 { 194 ACPI_STATUS Status; 195 196 197 Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER); 198 if (ACPI_FAILURE (Status)) 199 { 200 return (Status); 201 } 202 203 /* Acquire the write lock only for the first reader */ 204 205 Lock->NumReaders++; 206 if (Lock->NumReaders == 1) 207 { 208 Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER); 209 } 210 211 AcpiOsReleaseMutex (Lock->ReaderMutex); 212 return (Status); 213 } 214 215 216 ACPI_STATUS 217 AcpiUtReleaseReadLock ( 218 ACPI_RW_LOCK *Lock) 219 { 220 ACPI_STATUS Status; 221 222 223 Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER); 224 if (ACPI_FAILURE (Status)) 225 { 226 return (Status); 227 } 228 229 /* Release the write lock only for the very last reader */ 230 231 Lock->NumReaders--; 232 if (Lock->NumReaders == 0) 233 { 234 AcpiOsReleaseMutex (Lock->WriterMutex); 235 } 236 237 AcpiOsReleaseMutex (Lock->ReaderMutex); 238 return (Status); 239 } 240 241 242 /******************************************************************************* 243 * 244 * FUNCTION: AcpiUtAcquireWriteLock 245 * AcpiUtReleaseWriteLock 246 * 247 * PARAMETERS: Lock - Pointer to a valid RW lock 248 * 249 * RETURN: Status 250 * 251 * DESCRIPTION: Writer interfaces for reader/writer locks. Simply acquire or 252 * release the writer mutex associated with the lock. Acquisition 253 * of the lock is fully exclusive and will block all readers and 254 * writers until it is released. 255 * 256 ******************************************************************************/ 257 258 ACPI_STATUS 259 AcpiUtAcquireWriteLock ( 260 ACPI_RW_LOCK *Lock) 261 { 262 ACPI_STATUS Status; 263 264 265 Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER); 266 return (Status); 267 } 268 269 270 void 271 AcpiUtReleaseWriteLock ( 272 ACPI_RW_LOCK *Lock) 273 { 274 275 AcpiOsReleaseMutex (Lock->WriterMutex); 276 } 277 278