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c6bb62bc JA |
1 | #ifndef FIO_SEQLOCK_H |
2 | #define FIO_SEQLOCK_H | |
3 | ||
64dbaa7e | 4 | #include "types.h" |
c6bb62bc JA |
5 | #include "../arch/arch.h" |
6 | ||
7 | struct seqlock { | |
ecba19b6 | 8 | volatile unsigned int sequence; |
c6bb62bc JA |
9 | }; |
10 | ||
11 | static inline void seqlock_init(struct seqlock *s) | |
12 | { | |
13 | s->sequence = 0; | |
14 | } | |
15 | ||
16 | static inline unsigned int read_seqlock_begin(struct seqlock *s) | |
17 | { | |
18 | unsigned int seq; | |
19 | ||
20 | do { | |
5fa0c063 | 21 | seq = atomic_load_acquire(&s->sequence); |
c6bb62bc JA |
22 | if (!(seq & 1)) |
23 | break; | |
24 | nop; | |
25 | } while (1); | |
26 | ||
c6bb62bc JA |
27 | return seq; |
28 | } | |
29 | ||
30 | static inline bool read_seqlock_retry(struct seqlock *s, unsigned int seq) | |
31 | { | |
32 | read_barrier(); | |
33 | return s->sequence != seq; | |
34 | } | |
35 | ||
36 | static inline void write_seqlock_begin(struct seqlock *s) | |
37 | { | |
5fa0c063 | 38 | s->sequence = atomic_load_acquire(&s->sequence) + 1; |
c6bb62bc JA |
39 | } |
40 | ||
41 | static inline void write_seqlock_end(struct seqlock *s) | |
42 | { | |
5fa0c063 | 43 | atomic_store_release(&s->sequence, s->sequence + 1); |
c6bb62bc JA |
44 | } |
45 | ||
46 | #endif |