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    Subject[PATCH V5 07/17] 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 125bfda..4f59eae 100644
    --- a/tools/perf/util/mmap.c
    +++ b/tools/perf/util/mmap.c
    @@ -338,3 +338,14 @@ 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 9ab2b48..95549d4 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 *md, 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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