Commit | Line | Data |
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c6bb62bc JA |
1 | #ifndef FIO_SEQLOCK_H |
2 | #define FIO_SEQLOCK_H | |
3 | ||
4 | #include "../arch/arch.h" | |
5 | ||
6 | struct seqlock { | |
7 | volatile int sequence; | |
8 | }; | |
9 | ||
10 | static inline void seqlock_init(struct seqlock *s) | |
11 | { | |
12 | s->sequence = 0; | |
13 | } | |
14 | ||
15 | static inline unsigned int read_seqlock_begin(struct seqlock *s) | |
16 | { | |
17 | unsigned int seq; | |
18 | ||
19 | do { | |
20 | seq = s->sequence; | |
21 | if (!(seq & 1)) | |
22 | break; | |
23 | nop; | |
24 | } while (1); | |
25 | ||
26 | read_barrier(); | |
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 | { | |
38 | s->sequence++; | |
39 | write_barrier(); | |
40 | } | |
41 | ||
42 | static inline void write_seqlock_end(struct seqlock *s) | |
43 | { | |
44 | write_barrier(); | |
45 | s->sequence++; | |
46 | } | |
47 | ||
48 | #endif |