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-rw-r--r--tools/perf/lib/include/perf/mmap.h1
-rw-r--r--tools/perf/lib/libperf.map1
-rw-r--r--tools/perf/lib/mmap.c17
3 files changed, 19 insertions, 0 deletions
diff --git a/tools/perf/lib/include/perf/mmap.h b/tools/perf/lib/include/perf/mmap.h
index 646e9052b003..4f946e7f724b 100644
--- a/tools/perf/lib/include/perf/mmap.h
+++ b/tools/perf/lib/include/perf/mmap.h
@@ -8,5 +8,6 @@ struct perf_mmap;
LIBPERF_API void perf_mmap__consume(struct perf_mmap *map);
LIBPERF_API int perf_mmap__read_init(struct perf_mmap *map);
+LIBPERF_API void perf_mmap__read_done(struct perf_mmap *map);
#endif /* __LIBPERF_MMAP_H */
diff --git a/tools/perf/lib/libperf.map b/tools/perf/lib/libperf.map
index bc3fbb213a3e..7e3ea2e9c917 100644
--- a/tools/perf/lib/libperf.map
+++ b/tools/perf/lib/libperf.map
@@ -42,6 +42,7 @@ LIBPERF_0.0.1 {
perf_evlist__poll;
perf_mmap__consume;
perf_mmap__read_init;
+ perf_mmap__read_done;
local:
*;
};
diff --git a/tools/perf/lib/mmap.c b/tools/perf/lib/mmap.c
index fdbc6c550dea..97297cba44e3 100644
--- a/tools/perf/lib/mmap.c
+++ b/tools/perf/lib/mmap.c
@@ -175,3 +175,20 @@ int perf_mmap__read_init(struct perf_mmap *map)
return __perf_mmap__read_init(map);
}
+
+/*
+ * Mandatory for overwrite mode
+ * The direction of overwrite mode is backward.
+ * The last perf_mmap__read() will set tail to map->core.prev.
+ * Need to correct the map->core.prev to head which is the end of next read.
+ */
+void perf_mmap__read_done(struct perf_mmap *map)
+{
+ /*
+ * Check if event was unmapped due to a POLLHUP/POLLERR.
+ */
+ if (!refcount_read(&map->refcnt))
+ return;
+
+ map->prev = perf_mmap__read_head(map);
+}