[PATCH v1 4/5] perf dso: With ref count checking, avoid dso_data holding dso live

[Ian Rogers <irogers@google.com>]

With the dso_data embedded in a dso there is a reference counted
pointer to the dso rather than using container_of with reference count
checking. This data can hold the dso live meaning that no dso__put
ever deletes it. Add a check for this case and close the dso_data when
it happens. There isn't an infinite loop as the dso_data clears the
file descriptor prior to putting on the dso.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/dso.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 057fcf4225ac..c6c1637e098c 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1612,6 +1612,10 @@ struct dso *dso__get(struct dso *dso)
 
 void dso__put(struct dso *dso)
 {
+#ifdef REFCNT_CHECKING
+	if (dso && dso__data(dso) && refcount_read(&RC_CHK_ACCESS(dso)->refcnt) == 2)
+		dso__data_close(dso);
+#endif
 	if (dso && refcount_dec_and_test(&RC_CHK_ACCESS(dso)->refcnt))
 		dso__delete(dso);
 	else
-- 
2.50.0.714.g196bf9f422-goog