projects / fio.git / blame
| Commit | Line | Data |
|---|---|---|
| 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 |