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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __PERF_MUTEX_H
#define __PERF_MUTEX_H
#include <pthread.h>
#include <stdbool.h>
/*
* A function-like feature checking macro that is a wrapper around
* `__has_attribute`, which is defined by GCC 5+ and Clang and evaluates to a
* nonzero constant integer if the attribute is supported or 0 if not.
*/
#ifdef __has_attribute
#define HAVE_ATTRIBUTE(x) __has_attribute(x)
#else
#define HAVE_ATTRIBUTE(x) 0
#endif
#if HAVE_ATTRIBUTE(guarded_by) && HAVE_ATTRIBUTE(pt_guarded_by) && \
HAVE_ATTRIBUTE(lockable) && HAVE_ATTRIBUTE(exclusive_lock_function) && \
HAVE_ATTRIBUTE(exclusive_trylock_function) && HAVE_ATTRIBUTE(exclusive_locks_required) && \
HAVE_ATTRIBUTE(no_thread_safety_analysis)
/* Documents if a shared field or global variable needs to be protected by a mutex. */
#define GUARDED_BY(x) __attribute__((guarded_by(x)))
/*
* Documents if the memory location pointed to by a pointer should be guarded by
* a mutex when dereferencing the pointer.
*/
#define PT_GUARDED_BY(x) __attribute__((pt_guarded_by(x)))
/* Documents if a type is a lockable type. */
#define LOCKABLE __attribute__((lockable))
/* Documents a function that expects a lock not to be held prior to entry. */
#define LOCKS_EXCLUDED(...) __attribute__((locks_excluded(__VA_ARGS__)))
/* Documents a function that returns a lock. */
#define LOCK_RETURNED(x) __attribute__((lock_returned(x)))
/* Documents functions that acquire a lock in the body of a function, and do not release it. */
#define EXCLUSIVE_LOCK_FUNCTION(...) __attribute__((exclusive_lock_function(__VA_ARGS__)))
/*
* Documents functions that acquire a shared (reader) lock in the body of a
* function, and do not release it.
*/
#define SHARED_LOCK_FUNCTION(...) __attribute__((shared_lock_function(__VA_ARGS__)))
/*
* Documents functions that expect a lock to be held on entry to the function,
* and release it in the body of the function.
*/
#define UNLOCK_FUNCTION(...) __attribute__((unlock_function(__VA_ARGS__)))
/* Documents functions that try to acquire a lock, and return success or failure. */
#define EXCLUSIVE_TRYLOCK_FUNCTION(...) \
__attribute__((exclusive_trylock_function(__VA_ARGS__)))
/* Documents a function that expects a mutex to be held prior to entry. */
#define EXCLUSIVE_LOCKS_REQUIRED(...) __attribute__((exclusive_locks_required(__VA_ARGS__)))
/* Documents a function that expects a shared (reader) lock to be held prior to entry. */
#define SHARED_LOCKS_REQUIRED(...) __attribute__((shared_locks_required(__VA_ARGS__)))
/* Turns off thread safety checking within the body of a particular function. */
#define NO_THREAD_SAFETY_ANALYSIS __attribute__((no_thread_safety_analysis))
#else
#define GUARDED_BY(x)
#define PT_GUARDED_BY(x)
#define LOCKABLE
#define LOCKS_EXCLUDED(...)
#define LOCK_RETURNED(x)
#define EXCLUSIVE_LOCK_FUNCTION(...)
#define SHARED_LOCK_FUNCTION(...)
#define UNLOCK_FUNCTION(...)
#define EXCLUSIVE_TRYLOCK_FUNCTION(...)
#define EXCLUSIVE_LOCKS_REQUIRED(...)
#define SHARED_LOCKS_REQUIRED(...)
#define NO_THREAD_SAFETY_ANALYSIS
#endif
/*
* A wrapper around the mutex implementation that allows perf to error check
* usage, etc.
*/
struct LOCKABLE mutex {
pthread_mutex_t lock;
};
/*
* Statically initialized mutex, for the file scope ones. Error checking
* in !NDEBUG builds, like mutex_init(); the glibc-only errorcheck
* initializer falls back to the default type elsewhere.
*/
#if !defined(NDEBUG) && defined(PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP)
#define __PERF_MUTEX_INITIALIZER PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
#else
#define __PERF_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
#endif
#define DEFINE_MUTEX(name) struct mutex name = { .lock = __PERF_MUTEX_INITIALIZER }
/*
* Runs fn() exactly once however many threads race to it, the rest wait
* for it to finish; per call site state, so multiple sites wanting the
* same once use a common helper, as in the kernel's DO_ONCE().
*/
#define DO_ONCE(fn, ...) \
({ \
static bool ___done; \
static DEFINE_MUTEX(___once_lock); \
bool ___ret = false; \
\
if (!__atomic_load_n(&___done, __ATOMIC_ACQUIRE)) { \
mutex_lock(&___once_lock); \
if (!___done) { \
fn(__VA_ARGS__); \
__atomic_store_n(&___done, true, \
__ATOMIC_RELEASE); \
___ret = true; \
} \
mutex_unlock(&___once_lock); \
} \
___ret; \
})
/* A wrapper around the condition variable implementation. */
struct cond {
pthread_cond_t cond;
};
/* Default initialize the mtx struct. */
void mutex_init(struct mutex *mtx);
/*
* Initialize the mtx struct and set the process-shared rather than default
* process-private attribute.
*/
void mutex_init_pshared(struct mutex *mtx);
/* Initializes a mutex that may be recursively held on the same thread. */
void mutex_init_recursive(struct mutex *mtx);
/*
* As mutex_init_pshared(), plus the robust attribute: a process dying while
* holding it doesn't leave it locked, but the takeover isn't reported and the
* data it protects may be mid update. Returns false when not available.
*/
bool mutex_init_pshared_robust(struct mutex *mtx);
void mutex_destroy(struct mutex *mtx);
void mutex_lock(struct mutex *mtx) EXCLUSIVE_LOCK_FUNCTION(*mtx);
void mutex_unlock(struct mutex *mtx) UNLOCK_FUNCTION(*mtx);
/* Tries to acquire the lock and returns true on success. */
bool mutex_trylock(struct mutex *mtx) EXCLUSIVE_TRYLOCK_FUNCTION(true, *mtx);
/* Default initialize the cond struct. */
void cond_init(struct cond *cnd);
/*
* Initialize the cond struct and specify the process-shared rather than default
* process-private attribute.
*/
void cond_init_pshared(struct cond *cnd);
void cond_destroy(struct cond *cnd);
void cond_wait(struct cond *cnd, struct mutex *mtx) EXCLUSIVE_LOCKS_REQUIRED(mtx);
void cond_signal(struct cond *cnd);
void cond_broadcast(struct cond *cnd);
#endif /* __PERF_MUTEX_H */
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