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 */
109
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