ReactOS  0.4.14-dev-1115-gebeeb9d
utlock.c
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1 /******************************************************************************
2  *
3  * Module Name: utlock - Reader/Writer lock interfaces
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2020, Intel Corp.
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  * notice, this list of conditions, and the following disclaimer,
16  * without modification.
17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
18  * substantially similar to the "NO WARRANTY" disclaimer below
19  * ("Disclaimer") and any redistribution must be conditioned upon
20  * including a substantially similar Disclaimer requirement for further
21  * binary redistribution.
22  * 3. Neither the names of the above-listed copyright holders nor the names
23  * of any contributors may be used to endorse or promote products derived
24  * from this software without specific prior written permission.
25  *
26  * Alternatively, this software may be distributed under the terms of the
27  * GNU General Public License ("GPL") version 2 as published by the Free
28  * Software Foundation.
29  *
30  * NO WARRANTY
31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41  * POSSIBILITY OF SUCH DAMAGES.
42  */
43 
44 #include "acpi.h"
45 #include "accommon.h"
46 
47 
48 #define _COMPONENT ACPI_UTILITIES
49  ACPI_MODULE_NAME ("utlock")
50 
51 
52 /*******************************************************************************
53  *
54  * FUNCTION: AcpiUtCreateRwLock
55  * AcpiUtDeleteRwLock
56  *
57  * PARAMETERS: Lock - Pointer to a valid RW lock
58  *
59  * RETURN: Status
60  *
61  * DESCRIPTION: Reader/writer lock creation and deletion interfaces.
62  *
63  ******************************************************************************/
64 
68 {
70 
71 
72  Lock->NumReaders = 0;
73  Status = AcpiOsCreateMutex (&Lock->ReaderMutex);
74  if (ACPI_FAILURE (Status))
75  {
76  return (Status);
77  }
78 
79  Status = AcpiOsCreateMutex (&Lock->WriterMutex);
80  return (Status);
81 }
82 
83 
84 void
87 {
88 
89  AcpiOsDeleteMutex (Lock->ReaderMutex);
90  AcpiOsDeleteMutex (Lock->WriterMutex);
91 
92  Lock->NumReaders = 0;
93  Lock->ReaderMutex = NULL;
94  Lock->WriterMutex = NULL;
95 }
96 
97 
98 /*******************************************************************************
99  *
100  * FUNCTION: AcpiUtAcquireReadLock
101  * AcpiUtReleaseReadLock
102  *
103  * PARAMETERS: Lock - Pointer to a valid RW lock
104  *
105  * RETURN: Status
106  *
107  * DESCRIPTION: Reader interfaces for reader/writer locks. On acquisition,
108  * only the first reader acquires the write mutex. On release,
109  * only the last reader releases the write mutex. Although this
110  * algorithm can in theory starve writers, this should not be a
111  * problem with ACPICA since the subsystem is infrequently used
112  * in comparison to (for example) an I/O system.
113  *
114  ******************************************************************************/
115 
119 {
121 
122 
124  if (ACPI_FAILURE (Status))
125  {
126  return (Status);
127  }
128 
129  /* Acquire the write lock only for the first reader */
130 
131  Lock->NumReaders++;
132  if (Lock->NumReaders == 1)
133  {
135  }
136 
137  AcpiOsReleaseMutex (Lock->ReaderMutex);
138  return (Status);
139 }
140 
141 
145 {
147 
148 
150  if (ACPI_FAILURE (Status))
151  {
152  return (Status);
153  }
154 
155  /* Release the write lock only for the very last reader */
156 
157  Lock->NumReaders--;
158  if (Lock->NumReaders == 0)
159  {
160  AcpiOsReleaseMutex (Lock->WriterMutex);
161  }
162 
163  AcpiOsReleaseMutex (Lock->ReaderMutex);
164  return (Status);
165 }
166 
167 
168 /*******************************************************************************
169  *
170  * FUNCTION: AcpiUtAcquireWriteLock
171  * AcpiUtReleaseWriteLock
172  *
173  * PARAMETERS: Lock - Pointer to a valid RW lock
174  *
175  * RETURN: Status
176  *
177  * DESCRIPTION: Writer interfaces for reader/writer locks. Simply acquire or
178  * release the writer mutex associated with the lock. Acquisition
179  * of the lock is fully exclusive and will block all readers and
180  * writers until it is released.
181  *
182  ******************************************************************************/
183 
187 {
189 
190 
192  return (Status);
193 }
194 
195 
196 void
199 {
200 
201  AcpiOsReleaseMutex (Lock->WriterMutex);
202 }
void AcpiUtReleaseWriteLock(ACPI_RW_LOCK *Lock)
Definition: utlock.c:197
ACPI_STATUS AcpiUtAcquireReadLock(ACPI_RW_LOCK *Lock)
Definition: utlock.c:117
ACPI_STATUS AcpiOsAcquireMutex(ACPI_MUTEX Handle, UINT16 Timeout)
Definition: osl.c:306
UINT32 ACPI_STATUS
Definition: actypes.h:460
ACPI_STATUS AcpiUtAcquireWriteLock(ACPI_RW_LOCK *Lock)
Definition: utlock.c:185
#define ACPI_FAILURE(a)
Definition: acexcep.h:95
ACPI_STATUS AcpiUtReleaseReadLock(ACPI_RW_LOCK *Lock)
Definition: utlock.c:143
#define ACPI_MODULE_NAME(Name)
Definition: acoutput.h:216
smooth NULL
Definition: ftsmooth.c:416
#define ACPI_WAIT_FOREVER
Definition: actypes.h:501
void AcpiUtDeleteRwLock(ACPI_RW_LOCK *Lock)
Definition: utlock.c:85
ACPI_STATUS AcpiUtCreateRwLock(ACPI_RW_LOCK *Lock)
Definition: utlock.c:66
IN OUT PLONG IN OUT PLONG Addend IN OUT PLONG IN LONG IN OUT PLONG IN LONG Increment IN PNDIS_RW_LOCK Lock
Definition: CrNtStubs.h:75
Status
Definition: gdiplustypes.h:24
ACPI_STATUS AcpiOsCreateMutex(ACPI_MUTEX *OutHandle)
Definition: osl.c:271
void AcpiOsReleaseMutex(ACPI_MUTEX Handle)
Definition: osl.c:333
void AcpiOsDeleteMutex(ACPI_MUTEX Handle)
Definition: osl.c:293