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48 lines
759 B
C
48 lines
759 B
C
#ifndef __LINUX_SEQLOCK_H
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#define __LINUX_SEQLOCK_H
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#include <linux/compiler.h>
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typedef struct seqcount {
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unsigned sequence;
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} seqcount_t;
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static inline void seqcount_init(seqcount_t *s)
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{
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s->sequence = 0;
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}
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static inline unsigned read_seqcount_begin(const seqcount_t *s)
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{
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unsigned ret;
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repeat:
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ret = READ_ONCE(s->sequence);
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if (unlikely(ret & 1)) {
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cpu_relax();
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goto repeat;
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}
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smp_rmb();
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return ret;
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}
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static inline int read_seqcount_retry(const seqcount_t *s, unsigned start)
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{
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smp_rmb();
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return unlikely(s->sequence != start);
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}
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static inline void write_seqcount_begin(seqcount_t *s)
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{
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s->sequence++;
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smp_wmb();
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}
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static inline void write_seqcount_end(seqcount_t *s)
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{
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smp_wmb();
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s->sequence++;
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}
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#endif /* __LINUX_SEQLOCK_H */
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