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 */