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#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 */
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