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 functions that acquire a lock in the body of a function, and do not release it. */
37#define EXCLUSIVE_LOCK_FUNCTION(...)  __attribute__((exclusive_lock_function(__VA_ARGS__)))
38
39/*
40 * Documents functions that expect a lock to be held on entry to the function,
41 * and release it in the body of the function.
42 */
43#define UNLOCK_FUNCTION(...) __attribute__((unlock_function(__VA_ARGS__)))
44
45/* Documents functions that try to acquire a lock, and return success or failure. */
46#define EXCLUSIVE_TRYLOCK_FUNCTION(...) \
47	__attribute__((exclusive_trylock_function(__VA_ARGS__)))
48
49/* Documents a function that expects a mutex to be held prior to entry. */
50#define EXCLUSIVE_LOCKS_REQUIRED(...) __attribute__((exclusive_locks_required(__VA_ARGS__)))
51
52/* Turns off thread safety checking within the body of a particular function. */
53#define NO_THREAD_SAFETY_ANALYSIS __attribute__((no_thread_safety_analysis))
54
55#else
56
57#define GUARDED_BY(x)
58#define PT_GUARDED_BY(x)
59#define LOCKABLE
60#define EXCLUSIVE_LOCK_FUNCTION(...)
61#define UNLOCK_FUNCTION(...)
62#define EXCLUSIVE_TRYLOCK_FUNCTION(...)
63#define EXCLUSIVE_LOCKS_REQUIRED(...)
64#define NO_THREAD_SAFETY_ANALYSIS
65
66#endif
67
68/*
69 * A wrapper around the mutex implementation that allows perf to error check
70 * usage, etc.
71 */
72struct LOCKABLE mutex {
73	pthread_mutex_t lock;
74};
75
76/* A wrapper around the condition variable implementation. */
77struct cond {
78	pthread_cond_t cond;
79};
80
81/* Default initialize the mtx struct. */
82void mutex_init(struct mutex *mtx);
83/*
84 * Initialize the mtx struct and set the process-shared rather than default
85 * process-private attribute.
86 */
87void mutex_init_pshared(struct mutex *mtx);
88void mutex_destroy(struct mutex *mtx);
89
90void mutex_lock(struct mutex *mtx) EXCLUSIVE_LOCK_FUNCTION(*mtx);
91void mutex_unlock(struct mutex *mtx) UNLOCK_FUNCTION(*mtx);
92/* Tries to acquire the lock and returns true on success. */
93bool mutex_trylock(struct mutex *mtx) EXCLUSIVE_TRYLOCK_FUNCTION(true, *mtx);
94
95/* Default initialize the cond struct. */
96void cond_init(struct cond *cnd);
97/*
98 * Initialize the cond struct and specify the process-shared rather than default
99 * process-private attribute.
100 */
101void cond_init_pshared(struct cond *cnd);
102void cond_destroy(struct cond *cnd);
103
104void cond_wait(struct cond *cnd, struct mutex *mtx) EXCLUSIVE_LOCKS_REQUIRED(mtx);
105void cond_signal(struct cond *cnd);
106void cond_broadcast(struct cond *cnd);
107
108#endif /* __PERF_MUTEX_H */
109