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-rw-r--r--include/linux/seqlock.h29
1 files changed, 27 insertions, 2 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 535f158977b9..cc359636cfa3 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -117,6 +117,22 @@ repeat:
}
/**
+ * raw_read_seqcount - Read the raw seqcount
+ * @s: pointer to seqcount_t
+ * Returns: count to be passed to read_seqcount_retry
+ *
+ * raw_read_seqcount opens a read critical section of the given
+ * seqcount without any lockdep checking and without checking or
+ * masking the LSB. Calling code is responsible for handling that.
+ */
+static inline unsigned raw_read_seqcount(const seqcount_t *s)
+{
+ unsigned ret = ACCESS_ONCE(s->sequence);
+ smp_rmb();
+ return ret;
+}
+
+/**
* raw_read_seqcount_begin - start seq-read critical section w/o lockdep
* @s: pointer to seqcount_t
* Returns: count to be passed to read_seqcount_retry
@@ -164,8 +180,6 @@ static inline unsigned read_seqcount_begin(const seqcount_t *s)
static inline unsigned raw_seqcount_begin(const seqcount_t *s)
{
unsigned ret = ACCESS_ONCE(s->sequence);
-
- seqcount_lockdep_reader_access(s);
smp_rmb();
return ret & ~1;
}
@@ -220,6 +234,17 @@ static inline void raw_write_seqcount_end(seqcount_t *s)
}
/*
+ * raw_write_seqcount_latch - redirect readers to even/odd copy
+ * @s: pointer to seqcount_t
+ */
+static inline void raw_write_seqcount_latch(seqcount_t *s)
+{
+ smp_wmb(); /* prior stores before incrementing "sequence" */
+ s->sequence++;
+ smp_wmb(); /* increment "sequence" before following stores */
+}
+
+/*
* Sequence counter only version assumes that callers are using their
* own mutexing.
*/