Move c_src dirs back to toplevel

[bcachefs-tools-debian] / include / linux / seqlock.h

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
new file mode 100644 (file)
index 0000000..435420f
--- /dev/null
+++ b/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 */