1/*
2 * Copyright (c) 2000-2019 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29/*
30 *
31 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
32 *
33 * HISTORY
34 *
35 * 2001-01-17 gvdl Re-implement on IOCommandGate::commandSleep
36 * 11/13/2000 CJS Created IOCommandPool class and implementation
37 *
38 */
39
40/*!
41 * @header IOCommandPool
42 * @abstract
43 * This header contains the IOCommandPool class definition.
44 */
45
46#ifndef _IOKIT_IO_COMMAND_POOL_H_
47#define _IOKIT_IO_COMMAND_POOL_H_
48
49/*
50 * Kernel
51 */
52
53#if defined(KERNEL) && defined(__cplusplus)
54
55#include <kern/kern_types.h>
56#include <kern/queue.h>
57#include <IOKit/IOCommand.h>
58#include <IOKit/IOCommandGate.h>
59#include <IOKit/IOService.h>
60#include <IOKit/IOWorkLoop.h>
61#include <libkern/c++/OSPtr.h>
62
63/*!
64 * @class IOCommandPool
65 * @abstract Manipulates a pool of commands which inherit from IOCommand.
66 * @discussion
67 * The IOCommandPool class is used to manipulate a pool of commands which
68 * inherit from IOCommand. It includes a factory method to create a pool
69 * of a certain size. Once the factory method is invoked, the semaphore
70 * is set to zero. The caller must then put commands in the pool by creating
71 * the command (via the controller's factory method or a memory allocation)
72 * and calling the returnCommand method with the newly created command as its
73 * argument.
74 */
75
76class IOCommandPool : public OSObject
77{
78 OSDeclareDefaultStructors(IOCommandPool);
79
80
81protected:
82
83 queue_head_t fQueueHead; /* head of the queue of elements available */
84 UInt32 fSleepers; /* Count of threads sleeping on this pool */
85 OSPtr<IOCommandGate> fSerializer; /* command gate used for serializing pool access */
86
87/*! @struct ExpansionData
88 * @discussion This structure will be used to expand the capablilties of the IOEventSource in the future.
89 */
90 struct ExpansionData { };
91
92/*! @var reserved
93 * Reserved for future use. (Internal use only) */
94 ExpansionData *reserved;
95
96/*!
97 * @const kIOCommandPoolDefaultSize
98 * @abstract The default size of any command pool.
99 * @discussion
100 * kIOCommandPoolDefaultSize is the default size of any command pool.
101 * The default size was determined to be the smallest size for which
102 * a pool makes sense.
103 */
104
105 static const UInt32 kIOCommandPoolDefaultSize = 2;
106
107/*
108 * Free all of this object's outstanding resources.
109 */
110
111 virtual void free(void) APPLE_KEXT_OVERRIDE;
112
113
114public:
115
116/*!
117 * @function initWithWorkLoop
118 * @abstract Primary initializer for an IOCommandPool object.
119 * @discussion Primary initializer for an IOCommandPool.
120 * Should probably use IOCommandPool::withWorkLoop() as it is easier to use.
121 * @param workLoop
122 * The workloop that this command pool should synchronize with.
123 * @result Returns true if command pool was successfully initialized.
124 */
125 virtual bool initWithWorkLoop(IOWorkLoop *workLoop);
126
127/*!
128 * @function withWorkLoop
129 * @abstract Primary factory method for the IOCommandPool class
130 * @discussion
131 * The withWorkLoop method is what is known as a factory method. It creates
132 * a new instance of an IOCommandPool and returns a pointer to that object.
133 * @param inWorkLoop
134 * The workloop that this command pool should synchronize with.
135 * @result
136 * Returns a pointer to an instance of IOCommandPool if successful,
137 * otherwise NULL.
138 */
139
140 static OSPtr<IOCommandPool> withWorkLoop(IOWorkLoop *inWorkLoop);
141
142/*!
143 * @function init
144 * @abstract Should never be used, obsolete. See initWithWorkLoop.
145 */
146 virtual bool init(IOService *inOwner,
147 IOWorkLoop *inWorkLoop,
148 UInt32 inSize = kIOCommandPoolDefaultSize);
149
150/*!
151 * @function withWorkLoop
152 * @abstract Should never be used, obsolete. See IOCommandPool::withWorkLoop.
153 */
154 static OSPtr<IOCommandPool> commandPool(IOService *inOwner,
155 IOWorkLoop *inWorkLoop,
156 UInt32 inSize = kIOCommandPoolDefaultSize);
157
158
159/*!
160 * @function getCommand
161 * @discussion The getCommand method is used to get a pointer to an object of type IOCommand from the pool.
162 * @param blockForCommand
163 * If the caller would like to have its thread slept until a command is
164 * available, it should pass true, else false.
165 * @result
166 * If the caller passes true in blockForCommand, getCommand guarantees that
167 * the result will be a pointer to an IOCommand object from the pool. If
168 * the caller passes false, s/he is responsible for checking whether a non-NULL
169 * pointer was returned.
170 */
171
172 virtual OSPtr<IOCommand> getCommand(
173 bool blockForCommand = true);
174
175/*!
176 * @function returnCommand
177 * @discussion
178 * The returnCommand method is used to place an object of type IOCommand
179 * into the pool, whether it be the first time, or the 1000th time.
180 * @param command
181 * The command to place in the pool.
182 */
183
184 virtual void returnCommand(LIBKERN_CONSUMED IOCommand *command);
185
186protected:
187
188/*!
189 * @function gatedGetCommand
190 * @discussion
191 * The gatedGetCommand method is used to serialize the extraction of a
192 * command from the pool behind a command gate, runAction-ed by getCommand.
193 * @param command
194 * A pointer to a pointer to an IOCommand object where the returned
195 * command will be stored.
196 * @param blockForCommand
197 * A bool that indicates whether to block the request until a command
198 * becomes available.
199 * @result
200 * Returns kIOReturnNoResources if no command is available and the client
201 * doesn't wish to block until one does become available.
202 * kIOReturnSuccess if the vCommand argument is valid.
203 */
204 virtual IOReturn gatedGetCommand(
205 LIBKERN_RETURNS_NOT_RETAINED IOCommand **command, bool blockForCommand);
206
207/*!
208 * @function gatedReturnCommand
209 * @discussion
210 * The gatedReturnCommand method is used to serialize the return of a
211 * command to the pool behind a command gate, runAction-ed by returnCommand.
212 * @param command
213 * A pointer to the IOCommand object to be returned to the pool.
214 * @result
215 * Always returns kIOReturnSuccess if the vCommand argument is valid.
216 */
217 virtual IOReturn gatedReturnCommand(IOCommand *command);
218
219private:
220 OSMetaClassDeclareReservedUnused(IOCommandPool, 0);
221 OSMetaClassDeclareReservedUnused(IOCommandPool, 1);
222 OSMetaClassDeclareReservedUnused(IOCommandPool, 2);
223 OSMetaClassDeclareReservedUnused(IOCommandPool, 3);
224 OSMetaClassDeclareReservedUnused(IOCommandPool, 4);
225 OSMetaClassDeclareReservedUnused(IOCommandPool, 5);
226 OSMetaClassDeclareReservedUnused(IOCommandPool, 6);
227 OSMetaClassDeclareReservedUnused(IOCommandPool, 7);
228};
229
230#endif /* defined(KERNEL) && defined(__cplusplus) */
231
232#endif /* _IOKIT_IO_COMMAND_POOL_H_ */
233