1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Mutexes: blocking mutual exclusion locks
4 *
5 * started by Ingo Molnar:
6 *
7 * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
8 *
9 * This file contains the main data structure and API definitions.
10 */
11 #ifndef __LINUX_MUTEX_H
12 #define __LINUX_MUTEX_H
13
14 #include <asm/current.h>
15 #include <linux/list.h>
16 #include <linux/spinlock_types.h>
17 #include <linux/lockdep.h>
18 #include <linux/atomic.h>
19 #include <asm/processor.h>
20 #include <linux/osq_lock.h>
21 #include <linux/debug_locks.h>
22 #include <linux/android_vendor.h>
23
24 #ifdef CONFIG_DEBUG_LOCK_ALLOC
25 # define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
26 , .dep_map = { \
27 .name = #lockname, \
28 .wait_type_inner = LD_WAIT_SLEEP, \
29 }
30 #else
31 # define __DEP_MAP_MUTEX_INITIALIZER(lockname)
32 #endif
33
34 #ifndef CONFIG_PREEMPT_RT
35
36 /*
37 * Simple, straightforward mutexes with strict semantics:
38 *
39 * - only one task can hold the mutex at a time
40 * - only the owner can unlock the mutex
41 * - multiple unlocks are not permitted
42 * - recursive locking is not permitted
43 * - a mutex object must be initialized via the API
44 * - a mutex object must not be initialized via memset or copying
45 * - task may not exit with mutex held
46 * - memory areas where held locks reside must not be freed
47 * - held mutexes must not be reinitialized
48 * - mutexes may not be used in hardware or software interrupt
49 * contexts such as tasklets and timers
50 *
51 * These semantics are fully enforced when DEBUG_MUTEXES is
52 * enabled. Furthermore, besides enforcing the above rules, the mutex
53 * debugging code also implements a number of additional features
54 * that make lock debugging easier and faster:
55 *
56 * - uses symbolic names of mutexes, whenever they are printed in debug output
57 * - point-of-acquire tracking, symbolic lookup of function names
58 * - list of all locks held in the system, printout of them
59 * - owner tracking
60 * - detects self-recursing locks and prints out all relevant info
61 * - detects multi-task circular deadlocks and prints out all affected
62 * locks and tasks (and only those tasks)
63 */
64 struct mutex {
65 atomic_long_t owner;
66 raw_spinlock_t wait_lock;
67 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
68 struct optimistic_spin_queue osq; /* Spinner MCS lock */
69 #endif
70 struct list_head wait_list;
71 #ifdef CONFIG_DEBUG_MUTEXES
72 void *magic;
73 #endif
74 #ifdef CONFIG_DEBUG_LOCK_ALLOC
75 struct lockdep_map dep_map;
76 #endif
77 ANDROID_OEM_DATA_ARRAY(1, 2);
78 };
79
80 #ifdef CONFIG_DEBUG_MUTEXES
81
82 #define __DEBUG_MUTEX_INITIALIZER(lockname) \
83 , .magic = &lockname
84
85 extern void mutex_destroy(struct mutex *lock);
86
87 #else
88
89 # define __DEBUG_MUTEX_INITIALIZER(lockname)
90
mutex_destroy(struct mutex * lock)91 static inline void mutex_destroy(struct mutex *lock) {}
92
93 #endif
94
95 /**
96 * mutex_init - initialize the mutex
97 * @mutex: the mutex to be initialized
98 *
99 * Initialize the mutex to unlocked state.
100 *
101 * It is not allowed to initialize an already locked mutex.
102 */
103 #define mutex_init(mutex) \
104 do { \
105 static struct lock_class_key __key; \
106 \
107 __mutex_init((mutex), #mutex, &__key); \
108 } while (0)
109
110 #define __MUTEX_INITIALIZER(lockname) \
111 { .owner = ATOMIC_LONG_INIT(0) \
112 , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
113 , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \
114 __DEBUG_MUTEX_INITIALIZER(lockname) \
115 __DEP_MAP_MUTEX_INITIALIZER(lockname) }
116
117 #define DEFINE_MUTEX(mutexname) \
118 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
119
120 extern void __mutex_init(struct mutex *lock, const char *name,
121 struct lock_class_key *key);
122
123 /**
124 * mutex_is_locked - is the mutex locked
125 * @lock: the mutex to be queried
126 *
127 * Returns true if the mutex is locked, false if unlocked.
128 */
129 extern bool mutex_is_locked(struct mutex *lock);
130
131 #else /* !CONFIG_PREEMPT_RT */
132 /*
133 * Preempt-RT variant based on rtmutexes.
134 */
135 #include <linux/rtmutex.h>
136
137 struct mutex {
138 struct rt_mutex_base rtmutex;
139 #ifdef CONFIG_DEBUG_LOCK_ALLOC
140 struct lockdep_map dep_map;
141 #endif
142 };
143
144 #define __MUTEX_INITIALIZER(mutexname) \
145 { \
146 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex) \
147 __DEP_MAP_MUTEX_INITIALIZER(mutexname) \
148 }
149
150 #define DEFINE_MUTEX(mutexname) \
151 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
152
153 extern void __mutex_rt_init(struct mutex *lock, const char *name,
154 struct lock_class_key *key);
155 extern int mutex_trylock(struct mutex *lock);
156
mutex_destroy(struct mutex * lock)157 static inline void mutex_destroy(struct mutex *lock) { }
158
159 #define mutex_is_locked(l) rt_mutex_base_is_locked(&(l)->rtmutex)
160
161 #define __mutex_init(mutex, name, key) \
162 do { \
163 rt_mutex_base_init(&(mutex)->rtmutex); \
164 __mutex_rt_init((mutex), name, key); \
165 } while (0)
166
167 #define mutex_init(mutex) \
168 do { \
169 static struct lock_class_key __key; \
170 \
171 __mutex_init((mutex), #mutex, &__key); \
172 } while (0)
173 #endif /* CONFIG_PREEMPT_RT */
174
175 /*
176 * See kernel/locking/mutex.c for detailed documentation of these APIs.
177 * Also see Documentation/locking/mutex-design.rst.
178 */
179 #ifdef CONFIG_DEBUG_LOCK_ALLOC
180 extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
181 extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
182
183 extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
184 unsigned int subclass);
185 extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
186 unsigned int subclass);
187 extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
188
189 #define mutex_lock(lock) mutex_lock_nested(lock, 0)
190 #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
191 #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
192 #define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
193
194 #define mutex_lock_nest_lock(lock, nest_lock) \
195 do { \
196 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
197 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
198 } while (0)
199
200 #else
201 extern void mutex_lock(struct mutex *lock);
202 extern int __must_check mutex_lock_interruptible(struct mutex *lock);
203 extern int __must_check mutex_lock_killable(struct mutex *lock);
204 extern void mutex_lock_io(struct mutex *lock);
205
206 # define mutex_lock_nested(lock, subclass) mutex_lock(lock)
207 # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
208 # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
209 # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
210 # define mutex_lock_io_nested(lock, subclass) mutex_lock_io(lock)
211 #endif
212
213 /*
214 * NOTE: mutex_trylock() follows the spin_trylock() convention,
215 * not the down_trylock() convention!
216 *
217 * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
218 */
219 extern int mutex_trylock(struct mutex *lock);
220 extern void mutex_unlock(struct mutex *lock);
221
222 extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
223
224 #endif /* __LINUX_MUTEX_H */
225