1 // SPDX-License-Identifier: GPL-2.0-only
2 #ifndef _LINUX_RWBASE_RT_H
3 #define _LINUX_RWBASE_RT_H
4
5 #include <linux/rtmutex.h>
6 #include <linux/atomic.h>
7
8 #define READER_BIAS (1U << 31)
9 #define WRITER_BIAS (1U << 30)
10
11 struct rwbase_rt {
12 atomic_t readers;
13 struct rt_mutex_base rtmutex;
14 };
15
16 #define __RWBASE_INITIALIZER(name) \
17 { \
18 .readers = ATOMIC_INIT(READER_BIAS), \
19 .rtmutex = __RT_MUTEX_BASE_INITIALIZER(name.rtmutex), \
20 }
21
22 #define init_rwbase_rt(rwbase) \
23 do { \
24 rt_mutex_base_init(&(rwbase)->rtmutex); \
25 atomic_set(&(rwbase)->readers, READER_BIAS); \
26 } while (0)
27
28
29 static __always_inline bool rw_base_is_locked(const struct rwbase_rt *rwb)
30 {
31 return atomic_read(&rwb->readers) != READER_BIAS;
32 }
33
34 static __always_inline bool rw_base_is_write_locked(const struct rwbase_rt *rwb)
35 {
36 return atomic_read(&rwb->readers) == WRITER_BIAS;
37 }
38
39 static __always_inline bool rw_base_is_contended(const struct rwbase_rt *rwb)
40 {
41 return atomic_read(&rwb->readers) > 0;
42 }
43
44 #endif /* _LINUX_RWBASE_RT_H */
45
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