xref: /linux/include/linux/rwbase_rt.h (revision 3a07362fab1653d3aca31a9155c8cc776138fd02) 
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 
rw_base_is_locked(const struct rwbase_rt * rwb)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 
rw_base_is_write_locked(const struct rwbase_rt * rwb)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 
rw_base_is_contended(const struct rwbase_rt * rwb)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