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Ingo Molnar6053ee32006-01-09 15:59:19 -08001/*
2 * Mutexes: blocking mutual exclusion locks
3 *
4 * started by Ingo Molnar:
5 *
6 * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
7 *
8 * This file contains the main data structure and API definitions.
9 */
10#ifndef __LINUX_MUTEX_H
11#define __LINUX_MUTEX_H
12
Maarten Lankhorst040a0a32013-06-24 10:30:04 +020013#include <asm/current.h>
Ingo Molnar6053ee32006-01-09 15:59:19 -080014#include <linux/list.h>
15#include <linux/spinlock_types.h>
David S. Millera8b9ee72006-01-11 00:15:16 -080016#include <linux/linkage.h>
Ingo Molnaref5d4702006-07-03 00:24:55 -070017#include <linux/lockdep.h>
Arun Sharma600634972011-07-26 16:09:06 -070018#include <linux/atomic.h>
Heiko Carstens083986e2013-09-28 11:23:59 +020019#include <asm/processor.h>
Jason Low90631822014-07-14 10:27:49 -070020#include <linux/osq_lock.h>
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +020021#include <linux/debug_locks.h>
Ingo Molnar6053ee32006-01-09 15:59:19 -080022
23/*
24 * Simple, straightforward mutexes with strict semantics:
25 *
26 * - only one task can hold the mutex at a time
27 * - only the owner can unlock the mutex
28 * - multiple unlocks are not permitted
29 * - recursive locking is not permitted
30 * - a mutex object must be initialized via the API
31 * - a mutex object must not be initialized via memset or copying
32 * - task may not exit with mutex held
33 * - memory areas where held locks reside must not be freed
34 * - held mutexes must not be reinitialized
Matti Linnanvuorif20fda42007-10-16 23:29:41 -070035 * - mutexes may not be used in hardware or software interrupt
36 * contexts such as tasklets and timers
Ingo Molnar6053ee32006-01-09 15:59:19 -080037 *
38 * These semantics are fully enforced when DEBUG_MUTEXES is
39 * enabled. Furthermore, besides enforcing the above rules, the mutex
40 * debugging code also implements a number of additional features
41 * that make lock debugging easier and faster:
42 *
43 * - uses symbolic names of mutexes, whenever they are printed in debug output
44 * - point-of-acquire tracking, symbolic lookup of function names
45 * - list of all locks held in the system, printout of them
46 * - owner tracking
47 * - detects self-recursing locks and prints out all relevant info
48 * - detects multi-task circular deadlocks and prints out all affected
49 * locks and tasks (and only those tasks)
50 */
51struct mutex {
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +020052 atomic_long_t owner;
Ingo Molnar6053ee32006-01-09 15:59:19 -080053 spinlock_t wait_lock;
Waiman Long2bd2c922013-04-17 15:23:13 -040054#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
Jason Low90631822014-07-14 10:27:49 -070055 struct optimistic_spin_queue osq; /* Spinner MCS lock */
Waiman Long2bd2c922013-04-17 15:23:13 -040056#endif
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +020057 struct list_head wait_list;
Peter Zijlstra0d66bf62009-01-12 14:01:47 +010058#ifdef CONFIG_DEBUG_MUTEXES
Ingo Molnar6053ee32006-01-09 15:59:19 -080059 void *magic;
60#endif
Ingo Molnaref5d4702006-07-03 00:24:55 -070061#ifdef CONFIG_DEBUG_LOCK_ALLOC
62 struct lockdep_map dep_map;
63#endif
Ingo Molnar6053ee32006-01-09 15:59:19 -080064};
65
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +020066static inline struct task_struct *__mutex_owner(struct mutex *lock)
67{
68 return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x03);
69}
70
Ingo Molnar6053ee32006-01-09 15:59:19 -080071/*
72 * This is the control structure for tasks blocked on mutex,
73 * which resides on the blocked task's kernel stack:
74 */
75struct mutex_waiter {
76 struct list_head list;
77 struct task_struct *task;
78#ifdef CONFIG_DEBUG_MUTEXES
Ingo Molnar6053ee32006-01-09 15:59:19 -080079 void *magic;
80#endif
81};
82
83#ifdef CONFIG_DEBUG_MUTEXES
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +020084
85#define __DEBUG_MUTEX_INITIALIZER(lockname) \
86 , .magic = &lockname
87
88extern void mutex_destroy(struct mutex *lock);
89
Ingo Molnar6053ee32006-01-09 15:59:19 -080090#else
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +020091
Ingo Molnar6053ee32006-01-09 15:59:19 -080092# define __DEBUG_MUTEX_INITIALIZER(lockname)
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +020093
94static inline void mutex_destroy(struct mutex *lock) {}
95
96#endif
97
Randy Dunlapef5dc122010-09-02 15:48:16 -070098/**
99 * mutex_init - initialize the mutex
100 * @mutex: the mutex to be initialized
101 *
102 * Initialize the mutex to unlocked state.
103 *
104 * It is not allowed to initialize an already locked mutex.
105 */
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +0200106#define mutex_init(mutex) \
107do { \
108 static struct lock_class_key __key; \
109 \
110 __mutex_init((mutex), #mutex, &__key); \
Ingo Molnaref5d4702006-07-03 00:24:55 -0700111} while (0)
Ingo Molnar6053ee32006-01-09 15:59:19 -0800112
Ingo Molnaref5d4702006-07-03 00:24:55 -0700113#ifdef CONFIG_DEBUG_LOCK_ALLOC
114# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
115 , .dep_map = { .name = #lockname }
116#else
117# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
118#endif
119
Ingo Molnar6053ee32006-01-09 15:59:19 -0800120#define __MUTEX_INITIALIZER(lockname) \
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +0200121 { .owner = ATOMIC_LONG_INIT(0) \
Peter Zijlstra6cfd76a2006-12-06 20:37:22 -0800122 , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
Ingo Molnar6053ee32006-01-09 15:59:19 -0800123 , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \
Ingo Molnaref5d4702006-07-03 00:24:55 -0700124 __DEBUG_MUTEX_INITIALIZER(lockname) \
125 __DEP_MAP_MUTEX_INITIALIZER(lockname) }
Ingo Molnar6053ee32006-01-09 15:59:19 -0800126
127#define DEFINE_MUTEX(mutexname) \
128 struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
129
Ingo Molnaref5d4702006-07-03 00:24:55 -0700130extern void __mutex_init(struct mutex *lock, const char *name,
131 struct lock_class_key *key);
Ingo Molnar6053ee32006-01-09 15:59:19 -0800132
Robert P. J. Day45f8bde2007-01-26 00:57:09 -0800133/**
Ingo Molnar6053ee32006-01-09 15:59:19 -0800134 * mutex_is_locked - is the mutex locked
135 * @lock: the mutex to be queried
136 *
137 * Returns 1 if the mutex is locked, 0 if unlocked.
138 */
Harvey Harrisonec701582008-02-08 04:19:55 -0800139static inline int mutex_is_locked(struct mutex *lock)
Ingo Molnar6053ee32006-01-09 15:59:19 -0800140{
Peter Zijlstra3ca0ff52016-08-23 13:36:04 +0200141 /*
142 * XXX think about spin_is_locked
143 */
144 return __mutex_owner(lock) != NULL;
Ingo Molnar6053ee32006-01-09 15:59:19 -0800145}
146
147/*
Peter Zijlstra67a6de42013-11-08 08:26:39 +0100148 * See kernel/locking/mutex.c for detailed documentation of these APIs.
Davidlohr Bueso214e0ae2014-07-30 13:41:55 -0700149 * Also see Documentation/locking/mutex-design.txt.
Ingo Molnar6053ee32006-01-09 15:59:19 -0800150 */
Ingo Molnaref5d4702006-07-03 00:24:55 -0700151#ifdef CONFIG_DEBUG_LOCK_ALLOC
152extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
Peter Zijlstrae4c70a62011-05-24 17:12:03 -0700153extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
Maarten Lankhorst040a0a32013-06-24 10:30:04 +0200154
Andrew Morton18d83622007-05-09 02:33:39 -0700155extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
156 unsigned int subclass);
Liam R. Howlettad776532007-12-06 17:37:59 -0500157extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
158 unsigned int subclass);
Peter Zijlstrae4564f72007-10-11 22:11:12 +0200159
160#define mutex_lock(lock) mutex_lock_nested(lock, 0)
161#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
Liam R. Howlettad776532007-12-06 17:37:59 -0500162#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
Peter Zijlstrae4c70a62011-05-24 17:12:03 -0700163
164#define mutex_lock_nest_lock(lock, nest_lock) \
165do { \
Maarten Lankhorst040a0a32013-06-24 10:30:04 +0200166 typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
Peter Zijlstrae4c70a62011-05-24 17:12:03 -0700167 _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
168} while (0)
169
Ingo Molnaref5d4702006-07-03 00:24:55 -0700170#else
Harvey Harrisonec701582008-02-08 04:19:55 -0800171extern void mutex_lock(struct mutex *lock);
172extern int __must_check mutex_lock_interruptible(struct mutex *lock);
173extern int __must_check mutex_lock_killable(struct mutex *lock);
Peter Zijlstrae4564f72007-10-11 22:11:12 +0200174
Ingo Molnaref5d4702006-07-03 00:24:55 -0700175# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
NeilBrownd63a5a72006-12-08 02:36:17 -0800176# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
Liam R. Howlettad776532007-12-06 17:37:59 -0500177# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
Peter Zijlstrae4c70a62011-05-24 17:12:03 -0700178# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
Ingo Molnaref5d4702006-07-03 00:24:55 -0700179#endif
180
Ingo Molnar6053ee32006-01-09 15:59:19 -0800181/*
182 * NOTE: mutex_trylock() follows the spin_trylock() convention,
183 * not the down_trylock() convention!
Arjan van de Vend98d38f2008-10-29 14:24:09 -0700184 *
185 * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
Ingo Molnar6053ee32006-01-09 15:59:19 -0800186 */
Harvey Harrisonec701582008-02-08 04:19:55 -0800187extern int mutex_trylock(struct mutex *lock);
188extern void mutex_unlock(struct mutex *lock);
Maarten Lankhorst040a0a32013-06-24 10:30:04 +0200189
Andrew Mortona511e3f2009-04-29 15:59:58 -0700190extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
Eric Parisb1fca262009-03-23 18:22:09 +0100191
Peter Zijlstra0f5225b2016-10-07 17:43:51 +0200192/*
193 * These values are chosen such that FAIL and SUCCESS match the
194 * values of the regular mutex_trylock().
195 */
196enum mutex_trylock_recursive_enum {
197 MUTEX_TRYLOCK_FAILED = 0,
198 MUTEX_TRYLOCK_SUCCESS = 1,
199 MUTEX_TRYLOCK_RECURSIVE,
200};
201
202/**
203 * mutex_trylock_recursive - trylock variant that allows recursive locking
204 * @lock: mutex to be locked
205 *
206 * This function should not be used, _ever_. It is purely for hysterical GEM
207 * raisins, and once those are gone this will be removed.
208 *
209 * Returns:
210 * MUTEX_TRYLOCK_FAILED - trylock failed,
211 * MUTEX_TRYLOCK_SUCCESS - lock acquired,
212 * MUTEX_TRYLOCK_RECURSIVE - we already owned the lock.
213 */
Ingo Molnar43496d32016-11-16 10:36:05 +0100214static inline /* __deprecated */ __must_check enum mutex_trylock_recursive_enum
Peter Zijlstra0f5225b2016-10-07 17:43:51 +0200215mutex_trylock_recursive(struct mutex *lock)
216{
217 if (unlikely(__mutex_owner(lock) == current))
218 return MUTEX_TRYLOCK_RECURSIVE;
219
220 return mutex_trylock(lock);
221}
222
Tim Chene7224672014-01-21 15:36:00 -0800223#endif /* __LINUX_MUTEX_H */