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
AcpiUtCreateRwLock(ACPI_RW_LOCK * Lock)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
AcpiUtDeleteRwLock(ACPI_RW_LOCK * Lock)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
AcpiUtAcquireReadLock(ACPI_RW_LOCK * Lock)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
AcpiUtReleaseReadLock(ACPI_RW_LOCK * Lock)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
AcpiUtAcquireWriteLock(ACPI_RW_LOCK * Lock)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
AcpiUtReleaseWriteLock(ACPI_RW_LOCK * Lock)271 AcpiUtReleaseWriteLock (
272 ACPI_RW_LOCK *Lock)
273 {
274
275 AcpiOsReleaseMutex (Lock->WriterMutex);
276 }
277
278