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1498 | serge | 1 | /****************************************************************************** |
2 | * |
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3 | * Module Name: utlock - Reader/Writer lock interfaces |
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4 | * |
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5 | *****************************************************************************/ |
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6 | |||
7 | /****************************************************************************** |
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8 | * |
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9 | * 1. Copyright Notice |
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10 | * |
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11 | * Some or all of this work - Copyright (c) 1999 - 2010, Intel Corp. |
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12 | * All rights reserved. |
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13 | * |
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14 | * 2. License |
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15 | * |
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16 | * 2.1. This is your license from Intel Corp. under its intellectual property |
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17 | * rights. You may have additional license terms from the party that provided |
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18 | * you this software, covering your right to use that party's intellectual |
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19 | * property rights. |
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20 | * |
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21 | * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a |
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22 | * copy of the source code appearing in this file ("Covered Code") an |
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23 | * irrevocable, perpetual, worldwide license under Intel's copyrights in the |
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24 | * base code distributed originally by Intel ("Original Intel Code") to copy, |
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25 | * make derivatives, distribute, use and display any portion of the Covered |
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26 | * Code in any form, with the right to sublicense such rights; and |
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27 | * |
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28 | * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent |
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29 | * license (with the right to sublicense), under only those claims of Intel |
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30 | * patents that are infringed by the Original Intel Code, to make, use, sell, |
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31 | * offer to sell, and import the Covered Code and derivative works thereof |
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32 | * solely to the minimum extent necessary to exercise the above copyright |
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33 | * license, and in no event shall the patent license extend to any additions |
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34 | * to or modifications of the Original Intel Code. No other license or right |
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35 | * is granted directly or by implication, estoppel or otherwise; |
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36 | * |
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37 | * The above copyright and patent license is granted only if the following |
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38 | * conditions are met: |
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39 | * |
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40 | * 3. Conditions |
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41 | * |
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42 | * 3.1. Redistribution of Source with Rights to Further Distribute Source. |
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43 | * Redistribution of source code of any substantial portion of the Covered |
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44 | * Code or modification with rights to further distribute source must include |
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45 | * the above Copyright Notice, the above License, this list of Conditions, |
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46 | * and the following Disclaimer and Export Compliance provision. In addition, |
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47 | * Licensee must cause all Covered Code to which Licensee contributes to |
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48 | * contain a file documenting the changes Licensee made to create that Covered |
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49 | * Code and the date of any change. Licensee must include in that file the |
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50 | * documentation of any changes made by any predecessor Licensee. Licensee |
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51 | * must include a prominent statement that the modification is derived, |
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52 | * directly or indirectly, from Original Intel Code. |
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53 | * |
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54 | * 3.2. Redistribution of Source with no Rights to Further Distribute Source. |
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55 | * Redistribution of source code of any substantial portion of the Covered |
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56 | * Code or modification without rights to further distribute source must |
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57 | * include the following Disclaimer and Export Compliance provision in the |
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58 | * documentation and/or other materials provided with distribution. In |
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59 | * addition, Licensee may not authorize further sublicense of source of any |
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60 | * portion of the Covered Code, and must include terms to the effect that the |
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61 | * license from Licensee to its licensee is limited to the intellectual |
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62 | * property embodied in the software Licensee provides to its licensee, and |
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63 | * not to intellectual property embodied in modifications its licensee may |
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64 | * make. |
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65 | * |
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66 | * 3.3. Redistribution of Executable. Redistribution in executable form of any |
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67 | * substantial portion of the Covered Code or modification must reproduce the |
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68 | * above Copyright Notice, and the following Disclaimer and Export Compliance |
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69 | * provision in the documentation and/or other materials provided with the |
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70 | * distribution. |
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71 | * |
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72 | * 3.4. Intel retains all right, title, and interest in and to the Original |
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73 | * Intel Code. |
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74 | * |
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75 | * 3.5. Neither the name Intel nor any other trademark owned or controlled by |
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76 | * Intel shall be used in advertising or otherwise to promote the sale, use or |
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77 | * other dealings in products derived from or relating to the Covered Code |
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78 | * without prior written authorization from Intel. |
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79 | * |
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80 | * 4. Disclaimer and Export Compliance |
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81 | * |
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82 | * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED |
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83 | * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE |
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84 | * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE, |
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85 | * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY |
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86 | * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY |
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87 | * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A |
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88 | * PARTICULAR PURPOSE. |
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89 | * |
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90 | * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES |
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91 | * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR |
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92 | * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT, |
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93 | * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY |
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94 | * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL |
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95 | * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS |
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96 | * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY |
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97 | * LIMITED REMEDY. |
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98 | * |
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99 | * 4.3. Licensee shall not export, either directly or indirectly, any of this |
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100 | * software or system incorporating such software without first obtaining any |
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101 | * required license or other approval from the U. S. Department of Commerce or |
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102 | * any other agency or department of the United States Government. In the |
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103 | * event Licensee exports any such software from the United States or |
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104 | * re-exports any such software from a foreign destination, Licensee shall |
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105 | * ensure that the distribution and export/re-export of the software is in |
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106 | * compliance with all laws, regulations, orders, or other restrictions of the |
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107 | * U.S. Export Administration Regulations. Licensee agrees that neither it nor |
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108 | * any of its subsidiaries will export/re-export any technical data, process, |
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109 | * software, or service, directly or indirectly, to any country for which the |
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110 | * United States government or any agency thereof requires an export license, |
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111 | * other governmental approval, or letter of assurance, without first obtaining |
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112 | * such license, approval or letter. |
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113 | * |
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114 | *****************************************************************************/ |
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115 | |||
116 | #define __UTLOCK_C__ |
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117 | |||
118 | #include "acpi.h" |
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119 | #include "accommon.h" |
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120 | |||
121 | |||
122 | #define _COMPONENT ACPI_UTILITIES |
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123 | ACPI_MODULE_NAME ("utlock") |
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124 | |||
125 | |||
126 | /******************************************************************************* |
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127 | * |
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128 | * FUNCTION: AcpiUtCreateRwLock |
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129 | * AcpiUtDeleteRwLock |
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130 | * |
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131 | * PARAMETERS: Lock - Pointer to a valid RW lock |
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132 | * |
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133 | * RETURN: Status |
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134 | * |
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135 | * DESCRIPTION: Reader/writer lock creation and deletion interfaces. |
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136 | * |
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137 | ******************************************************************************/ |
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138 | |||
139 | ACPI_STATUS |
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140 | AcpiUtCreateRwLock ( |
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141 | ACPI_RW_LOCK *Lock) |
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142 | { |
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143 | ACPI_STATUS Status; |
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144 | |||
145 | |||
146 | Lock->NumReaders = 0; |
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147 | Status = AcpiOsCreateMutex (&Lock->ReaderMutex); |
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148 | if (ACPI_FAILURE (Status)) |
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149 | { |
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150 | return (Status); |
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151 | } |
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152 | |||
153 | Status = AcpiOsCreateMutex (&Lock->WriterMutex); |
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154 | return (Status); |
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155 | } |
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156 | |||
157 | |||
158 | void |
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159 | AcpiUtDeleteRwLock ( |
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160 | ACPI_RW_LOCK *Lock) |
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161 | { |
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162 | |||
163 | AcpiOsDeleteMutex (Lock->ReaderMutex); |
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164 | AcpiOsDeleteMutex (Lock->WriterMutex); |
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165 | |||
166 | Lock->NumReaders = 0; |
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167 | Lock->ReaderMutex = NULL; |
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168 | Lock->WriterMutex = NULL; |
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169 | } |
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170 | |||
171 | |||
172 | /******************************************************************************* |
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173 | * |
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174 | * FUNCTION: AcpiUtAcquireReadLock |
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175 | * AcpiUtReleaseReadLock |
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176 | * |
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177 | * PARAMETERS: Lock - Pointer to a valid RW lock |
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178 | * |
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179 | * RETURN: Status |
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180 | * |
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181 | * DESCRIPTION: Reader interfaces for reader/writer locks. On acquisition, |
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182 | * only the first reader acquires the write mutex. On release, |
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183 | * only the last reader releases the write mutex. Although this |
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184 | * algorithm can in theory starve writers, this should not be a |
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185 | * problem with ACPICA since the subsystem is infrequently used |
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186 | * in comparison to (for example) an I/O system. |
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187 | * |
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188 | ******************************************************************************/ |
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189 | |||
190 | ACPI_STATUS |
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191 | AcpiUtAcquireReadLock ( |
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192 | ACPI_RW_LOCK *Lock) |
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193 | { |
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194 | ACPI_STATUS Status; |
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195 | |||
196 | |||
197 | Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER); |
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198 | if (ACPI_FAILURE (Status)) |
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199 | { |
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200 | return (Status); |
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201 | } |
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202 | |||
203 | /* Acquire the write lock only for the first reader */ |
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204 | |||
205 | Lock->NumReaders++; |
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206 | if (Lock->NumReaders == 1) |
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207 | { |
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208 | Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER); |
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209 | } |
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210 | |||
211 | AcpiOsReleaseMutex (Lock->ReaderMutex); |
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212 | return (Status); |
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213 | } |
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214 | |||
215 | |||
216 | ACPI_STATUS |
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217 | AcpiUtReleaseReadLock ( |
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218 | ACPI_RW_LOCK *Lock) |
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219 | { |
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220 | ACPI_STATUS Status; |
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221 | |||
222 | |||
223 | Status = AcpiOsAcquireMutex (Lock->ReaderMutex, ACPI_WAIT_FOREVER); |
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224 | if (ACPI_FAILURE (Status)) |
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225 | { |
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226 | return (Status); |
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227 | } |
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228 | |||
229 | /* Release the write lock only for the very last reader */ |
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230 | |||
231 | Lock->NumReaders--; |
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232 | if (Lock->NumReaders == 0) |
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233 | { |
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234 | AcpiOsReleaseMutex (Lock->WriterMutex); |
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235 | } |
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236 | |||
237 | AcpiOsReleaseMutex (Lock->ReaderMutex); |
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238 | return (Status); |
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239 | } |
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240 | |||
241 | |||
242 | /******************************************************************************* |
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243 | * |
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244 | * FUNCTION: AcpiUtAcquireWriteLock |
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245 | * AcpiUtReleaseWriteLock |
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246 | * |
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247 | * PARAMETERS: Lock - Pointer to a valid RW lock |
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248 | * |
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249 | * RETURN: Status |
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250 | * |
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251 | * DESCRIPTION: Writer interfaces for reader/writer locks. Simply acquire or |
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252 | * release the writer mutex associated with the lock. Acquisition |
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253 | * of the lock is fully exclusive and will block all readers and |
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254 | * writers until it is released. |
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255 | * |
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256 | ******************************************************************************/ |
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257 | |||
258 | ACPI_STATUS |
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259 | AcpiUtAcquireWriteLock ( |
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260 | ACPI_RW_LOCK *Lock) |
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261 | { |
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262 | ACPI_STATUS Status; |
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263 | |||
264 | |||
265 | Status = AcpiOsAcquireMutex (Lock->WriterMutex, ACPI_WAIT_FOREVER); |
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266 | return (Status); |
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267 | } |
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268 | |||
269 | |||
270 | void |
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271 | AcpiUtReleaseWriteLock ( |
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272 | ACPI_RW_LOCK *Lock) |
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273 | { |
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274 | |||
275 | AcpiOsReleaseMutex (Lock->WriterMutex); |
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276 | } |
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277 |