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Subject[PATCH V4 05/15] perf mmap: introduce perf_mmap__read_done
Date
From: Kan Liang <kan.liang@intel.com>

The direction of overwrite mode is backward. The last perf_mmap__read()
will set tail to map->prev. Need to correct the map->prev to head which
is the end of next read.

It will be used later.

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
tools/perf/util/mmap.c | 11 +++++++++++
tools/perf/util/mmap.h | 1 +
2 files changed, 12 insertions(+)

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 2f2cc3a..2291160 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -342,3 +342,14 @@ int perf_mmap__push(struct perf_mmap *md, bool overwrite,
out:
return rc;
}
+
+/*
+ * Mandatory for overwrite mode
+ * The direction of overwrite mode is backward.
+ * The last perf_mmap__read() will set tail to map->prev.
+ * Need to correct the map->prev to head which is the end of next read.
+ */
+void perf_mmap__read_done(struct perf_mmap *map)
+{
+ map->prev = perf_mmap__read_head(map);
+}
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index 0633308..4434cc5 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -96,4 +96,5 @@ size_t perf_mmap__mmap_len(struct perf_mmap *map);

int perf_mmap__read_init(struct perf_mmap *map, bool overwrite,
u64 *startp, u64 *endp);
+void perf_mmap__read_done(struct perf_mmap *map);
#endif /*__PERF_MMAP_H */
--
2.5.5
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