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-rw-r--r--tools/perf/util/evlist.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 564b924..50420cd 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -974,8 +974,19 @@ static struct perf_mmap *perf_evlist__alloc_mmap(struct perf_evlist *evlist)
if (!map)
return NULL;
- for (i = 0; i < evlist->nr_mmaps; i++)
+ for (i = 0; i < evlist->nr_mmaps; i++) {
map[i].fd = -1;
+ /*
+ * When the perf_mmap() call is made we grab one refcount, plus
+ * one extra to let perf_evlist__mmap_consume() get the last
+ * events after all real references (perf_mmap__get()) are
+ * dropped.
+ *
+ * Each PERF_EVENT_IOC_SET_OUTPUT points to this mmap and
+ * thus does perf_mmap__get() on it.
+ */
+ refcount_set(&map[i].refcnt, 0);
+ }
return map;
}
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