Commit | Line | Data |
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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 { | |
8 | volatile int sequence; | |
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 { | |
21 | seq = s->sequence; | |
22 | if (!(seq & 1)) | |
23 | break; | |
24 | nop; | |
25 | } while (1); | |
26 | ||
27 | read_barrier(); | |
28 | return seq; | |
29 | } | |
30 | ||
31 | static inline bool read_seqlock_retry(struct seqlock *s, unsigned int seq) | |
32 | { | |
33 | read_barrier(); | |
34 | return s->sequence != seq; | |
35 | } | |
36 | ||
37 | static inline void write_seqlock_begin(struct seqlock *s) | |
38 | { | |
39 | s->sequence++; | |
40 | write_barrier(); | |
41 | } | |
42 | ||
43 | static inline void write_seqlock_end(struct seqlock *s) | |
44 | { | |
45 | write_barrier(); | |
46 | s->sequence++; | |
47 | } | |
48 | ||
49 | #endif |