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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __PERF_MUTEX_H
3#define __PERF_MUTEX_H
4
5#include <pthread.h>
6#include <stdbool.h>
7
8/*
9 * A function-like feature checking macro that is a wrapper around
10 * `__has_attribute`, which is defined by GCC 5+ and Clang and evaluates to a
11 * nonzero constant integer if the attribute is supported or 0 if not.
12 */
13#ifdef __has_attribute
14#define HAVE_ATTRIBUTE(x) __has_attribute(x)
15#else
16#define HAVE_ATTRIBUTE(x) 0
17#endif
18
19#if HAVE_ATTRIBUTE(guarded_by) && HAVE_ATTRIBUTE(pt_guarded_by) && \
20 HAVE_ATTRIBUTE(lockable) && HAVE_ATTRIBUTE(exclusive_lock_function) && \
21 HAVE_ATTRIBUTE(exclusive_trylock_function) && HAVE_ATTRIBUTE(exclusive_locks_required) && \
22 HAVE_ATTRIBUTE(no_thread_safety_analysis)
23
24/* Documents if a shared field or global variable needs to be protected by a mutex. */
25#define GUARDED_BY(x) __attribute__((guarded_by(x)))
26
27/*
28 * Documents if the memory location pointed to by a pointer should be guarded by
29 * a mutex when dereferencing the pointer.
30 */
31#define PT_GUARDED_BY(x) __attribute__((pt_guarded_by(x)))
32
33/* Documents if a type is a lockable type. */
34#define LOCKABLE __attribute__((lockable))
35
36/* Documents a function that expects a lock not to be held prior to entry. */
37#define LOCKS_EXCLUDED(...) __attribute__((locks_excluded(__VA_ARGS__)))
38
39/* Documents a function that returns a lock. */
40#define LOCK_RETURNED(x) __attribute__((lock_returned(x)))
41
42/* Documents functions that acquire a lock in the body of a function, and do not release it. */
43#define EXCLUSIVE_LOCK_FUNCTION(...) __attribute__((exclusive_lock_function(__VA_ARGS__)))
44
45/*
46 * Documents functions that acquire a shared (reader) lock in the body of a
47 * function, and do not release it.
48 */
49#define SHARED_LOCK_FUNCTION(...) __attribute__((shared_lock_function(__VA_ARGS__)))
50
51/*
52 * Documents functions that expect a lock to be held on entry to the function,
53 * and release it in the body of the function.
54 */
55#define UNLOCK_FUNCTION(...) __attribute__((unlock_function(__VA_ARGS__)))
56
57/* Documents functions that try to acquire a lock, and return success or failure. */
58#define EXCLUSIVE_TRYLOCK_FUNCTION(...) \
59 __attribute__((exclusive_trylock_function(__VA_ARGS__)))
60
61/* Documents a function that expects a mutex to be held prior to entry. */
62#define EXCLUSIVE_LOCKS_REQUIRED(...) __attribute__((exclusive_locks_required(__VA_ARGS__)))
63
64/* Documents a function that expects a shared (reader) lock to be held prior to entry. */
65#define SHARED_LOCKS_REQUIRED(...) __attribute__((shared_locks_required(__VA_ARGS__)))
66
67/* Turns off thread safety checking within the body of a particular function. */
68#define NO_THREAD_SAFETY_ANALYSIS __attribute__((no_thread_safety_analysis))
69
70#else
71
72#define GUARDED_BY(x)
73#define PT_GUARDED_BY(x)
74#define LOCKABLE
75#define LOCKS_EXCLUDED(...)
76#define LOCK_RETURNED(x)
77#define EXCLUSIVE_LOCK_FUNCTION(...)
78#define SHARED_LOCK_FUNCTION(...)
79#define UNLOCK_FUNCTION(...)
80#define EXCLUSIVE_TRYLOCK_FUNCTION(...)
81#define EXCLUSIVE_LOCKS_REQUIRED(...)
82#define SHARED_LOCKS_REQUIRED(...)
83#define NO_THREAD_SAFETY_ANALYSIS
84
85#endif
86
87/*
88 * A wrapper around the mutex implementation that allows perf to error check
89 * usage, etc.
90 */
91struct LOCKABLE mutex {
92 pthread_mutex_t lock;
93};
94
95/* A wrapper around the condition variable implementation. */
96struct cond {
97 pthread_cond_t cond;
98};
99
100/* Default initialize the mtx struct. */
101void mutex_init(struct mutex *mtx);
102/*
103 * Initialize the mtx struct and set the process-shared rather than default
104 * process-private attribute.
105 */
106void mutex_init_pshared(struct mutex *mtx);
107/* Initializes a mutex that may be recursively held on the same thread. */
108void mutex_init_recursive(struct mutex *mtx);
109void mutex_destroy(struct mutex *mtx);
110
111void mutex_lock(struct mutex *mtx) EXCLUSIVE_LOCK_FUNCTION(*mtx);
112void mutex_unlock(struct mutex *mtx) UNLOCK_FUNCTION(*mtx);
113/* Tries to acquire the lock and returns true on success. */
114bool mutex_trylock(struct mutex *mtx) EXCLUSIVE_TRYLOCK_FUNCTION(true, *mtx);
115
116/* Default initialize the cond struct. */
117void cond_init(struct cond *cnd);
118/*
119 * Initialize the cond struct and specify the process-shared rather than default
120 * process-private attribute.
121 */
122void cond_init_pshared(struct cond *cnd);
123void cond_destroy(struct cond *cnd);
124
125void cond_wait(struct cond *cnd, struct mutex *mtx) EXCLUSIVE_LOCKS_REQUIRED(mtx);
126void cond_signal(struct cond *cnd);
127void cond_broadcast(struct cond *cnd);
128
129#endif /* __PERF_MUTEX_H */