[PATCH v2 2/2] perf report: Fix memory leaks in the hierarchy mode

[Namhyung Kim <namhyung@kernel.org>]

Ian told me that there are many memory leaks in the hierarchy mode.  I
can easily reproduce it with the follwing command.

  $ make DEBUG=1 EXTRA_CFLAGS=-fsanitize=leak

  $ perf record --latency -g -- ./perf test -w thloop

  $ perf report -H --stdio
  ...
  Indirect leak of 168 byte(s) in 21 object(s) allocated from:
      #0 0x7f3414c16c65 in malloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:75
      #1 0x55ed3602346e in map__get util/map.h:189
      #2 0x55ed36024cc4 in hist_entry__init util/hist.c:476
      #3 0x55ed36025208 in hist_entry__new util/hist.c:588
      #4 0x55ed36027c05 in hierarchy_insert_entry util/hist.c:1587
      #5 0x55ed36027e2e in hists__hierarchy_insert_entry util/hist.c:1638
      #6 0x55ed36027fa4 in hists__collapse_insert_entry util/hist.c:1685
      #7 0x55ed360283e8 in hists__collapse_resort util/hist.c:1776
      #8 0x55ed35de0323 in report__collapse_hists /home/namhyung/project/linux/tools/perf/builtin-report.c:735
      #9 0x55ed35de15b4 in __cmd_report /home/namhyung/project/linux/tools/perf/builtin-report.c:1119
      #10 0x55ed35de43dc in cmd_report /home/namhyung/project/linux/tools/perf/builtin-report.c:1867
      #11 0x55ed35e66767 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:351
      #12 0x55ed35e66a0e in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:404
      #13 0x55ed35e66b67 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:448
      #14 0x55ed35e66eb0 in main /home/namhyung/project/linux/tools/perf/perf.c:556
      #15 0x7f340ac33d67 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
  ...

  $ perf report -H --stdio 2>&1 | grep -c '^Indirect leak'
  93

I found that hist_entry__delete() missed to release child entries in the
hierarchy tree (hroot_{in,out}).  It needs to iterate the child entries
and call hist_entry__delete() recursively.

After this change:

  $ perf report -H --stdio 2>&1 | grep -c '^Indirect leak'
  0

Reported-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
v2) Use rbtree_postorder_for_each_entry_safe()  (Ian)

 tools/perf/util/hist.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index fbf131aeae7ffe9b..d65228c1141251fb 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -1385,6 +1385,16 @@ void hist_entry__delete(struct hist_entry *he)
 {
 	struct hist_entry_ops *ops = he->ops;
 
+	if (symbol_conf.report_hierarchy) {
+		struct rb_root *root = &he->hroot_out.rb_root;
+		struct hist_entry *child, *tmp;
+
+		rbtree_postorder_for_each_entry_safe(child, tmp, root, rb_node)
+			hist_entry__delete(child);
+
+		*root = RB_ROOT;
+	}
+
 	thread__zput(he->thread);
 	map_symbol__exit(&he->ms);
 
-- 
2.49.0.rc0.332.g42c0ae87b1-goog