diff options
Diffstat (limited to 'c_src/include/linux/seqlock.h')
-rw-r--r-- | c_src/include/linux/seqlock.h | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/c_src/include/linux/seqlock.h b/c_src/include/linux/seqlock.h new file mode 100644 index 00000000..435420fe --- /dev/null +++ b/c_src/include/linux/seqlock.h @@ -0,0 +1,47 @@ +#ifndef __LINUX_SEQLOCK_H +#define __LINUX_SEQLOCK_H + +#include <linux/compiler.h> + +typedef struct seqcount { + unsigned sequence; +} seqcount_t; + +static inline void seqcount_init(seqcount_t *s) +{ + s->sequence = 0; +} + +static inline unsigned read_seqcount_begin(const seqcount_t *s) +{ + unsigned ret; + +repeat: + ret = READ_ONCE(s->sequence); + if (unlikely(ret & 1)) { + cpu_relax(); + goto repeat; + } + smp_rmb(); + return ret; +} + +static inline int read_seqcount_retry(const seqcount_t *s, unsigned start) +{ + smp_rmb(); + return unlikely(s->sequence != start); +} + +static inline void write_seqcount_begin(seqcount_t *s) +{ + s->sequence++; + smp_wmb(); +} + +static inline void write_seqcount_end(seqcount_t *s) +{ + smp_wmb(); + s->sequence++; +} + +#endif /* __LINUX_SEQLOCK_H */ |