tools/perf/util/mutex.h

   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  */
  72 struct LOCKABLE mutex {
  73         pthread_mutex_t lock;
  74 };
  75
  76 /* A wrapper around the condition variable implementation. */
  77 struct cond {
  78         pthread_cond_t cond;
  79 };
  80
  81 /* Default initialize the mtx struct. */
  82 void mutex_init(struct mutex *mtx);
  83 /*
  84  * Initialize the mtx struct and set the process-shared rather than default
  85  * process-private attribute.
  86  */
  87 void mutex_init_pshared(struct mutex *mtx);
  88 void mutex_destroy(struct mutex *mtx);
  89
  90 void mutex_lock(struct mutex *mtx) EXCLUSIVE_LOCK_FUNCTION(*mtx);
  91 void mutex_unlock(struct mutex *mtx) UNLOCK_FUNCTION(*mtx);
  92 /* Tries to acquire the lock and returns true on success. */
  93 bool mutex_trylock(struct mutex *mtx) EXCLUSIVE_TRYLOCK_FUNCTION(true, *mtx);
  94
  95 /* Default initialize the cond struct. */
  96 void cond_init(struct cond *cnd);
  97 /*
  98  * Initialize the cond struct and specify the process-shared rather than default
  99  * process-private attribute.
 100  */
 101 void cond_init_pshared(struct cond *cnd);
 102 void cond_destroy(struct cond *cnd);
 103
 104 void cond_wait(struct cond *cnd, struct mutex *mtx) EXCLUSIVE_LOCKS_REQUIRED(mtx);
 105 void cond_signal(struct cond *cnd);
 106 void cond_broadcast(struct cond *cnd);
 107
 108 #endif /* __PERF_MUTEX_H */