linux-kernel - [PATCH v1] perf hist: Fix reference counting of branch

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Message-Id: <20240807065136.1039977-1-irogers@google.com>
Date: Tue,  6 Aug 2024 23:51:36 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, Sun Haiyong <sunhaiyong@...ngson.cn>, 
	Yanteng Si <siyanteng@...ngson.cn>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: [PATCH v1] perf hist: Fix reference counting of branch_info

iter_finish_branch_entry doesn't put the branch_info from/to map
elements creating memory leaks. This can be seen with:

```
$ perf record -e cycles -b perf test -w noploop
$ perf report -D
...
Direct leak of 984344 byte(s) in 123043 object(s) allocated from:
    #0 0x7fb2654f3bd7 in malloc libsanitizer/asan/asan_malloc_linux.cpp:69
    #1 0x564d3400d10b in map__get util/map.h:186
    #2 0x564d3400d10b in ip__resolve_ams util/machine.c:1981
    #3 0x564d34014d81 in sample__resolve_bstack util/machine.c:2151
    #4 0x564d34094790 in iter_prepare_branch_entry util/hist.c:898
    #5 0x564d34098fa4 in hist_entry_iter__add util/hist.c:1238
    #6 0x564d33d1f0c7 in process_sample_event tools/perf/builtin-report.c:334
    #7 0x564d34031eb7 in perf_session__deliver_event util/session.c:1655
    #8 0x564d3403ba52 in do_flush util/ordered-events.c:245
    #9 0x564d3403ba52 in __ordered_events__flush util/ordered-events.c:324
    #10 0x564d3402d32e in perf_session__process_user_event util/session.c:1708
    #11 0x564d34032480 in perf_session__process_event util/session.c:1877
    #12 0x564d340336ad in reader__read_event util/session.c:2399
    #13 0x564d34033fdc in reader__process_events util/session.c:2448
    #14 0x564d34033fdc in __perf_session__process_events util/session.c:2495
    #15 0x564d34033fdc in perf_session__process_events util/session.c:2661
    #16 0x564d33d27113 in __cmd_report tools/perf/builtin-report.c:1065
    #17 0x564d33d27113 in cmd_report tools/perf/builtin-report.c:1805
    #18 0x564d33e0ccb7 in run_builtin tools/perf/perf.c:350
    #19 0x564d33e0d45e in handle_internal_command tools/perf/perf.c:403
    #20 0x564d33cdd827 in run_argv tools/perf/perf.c:447
    #21 0x564d33cdd827 in main tools/perf/perf.c:561
...
```

Clearing up the map_symbols properly creates maps reference count
issues so resolve those. Resolving this issue doesn't improve peak
heap consumption for the test above.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/hist.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index f8ee1cd6929d..c8c1b511f8a7 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -472,7 +472,9 @@ static int hist_entry__init(struct hist_entry *he,
 		memcpy(he->branch_info, template->branch_info,
 		       sizeof(*he->branch_info));
 
+		he->branch_info->from.ms.maps = maps__get(he->branch_info->from.ms.maps);
 		he->branch_info->from.ms.map = map__get(he->branch_info->from.ms.map);
+		he->branch_info->to.ms.maps = maps__get(he->branch_info->to.ms.maps);
 		he->branch_info->to.ms.map = map__get(he->branch_info->to.ms.map);
 	}
 
@@ -970,10 +972,21 @@ iter_add_next_branch_entry(struct hist_entry_iter *iter, struct addr_location *a
 	return err;
 }
 
+static void branch_info__exit(struct branch_info *bi)
+{
+	map_symbol__exit(&bi->from.ms);
+	map_symbol__exit(&bi->to.ms);
+	zfree_srcline(&bi->srcline_from);
+	zfree_srcline(&bi->srcline_to);
+}
+
 static int
 iter_finish_branch_entry(struct hist_entry_iter *iter,
 			 struct addr_location *al __maybe_unused)
 {
+	for (int i = 0; i < iter->total; i++)
+		branch_info__exit(&iter->bi[i]);
+
 	zfree(&iter->bi);
 	iter->he = NULL;
 
@@ -1319,10 +1332,7 @@ void hist_entry__delete(struct hist_entry *he)
 	map_symbol__exit(&he->ms);
 
 	if (he->branch_info) {
-		map_symbol__exit(&he->branch_info->from.ms);
-		map_symbol__exit(&he->branch_info->to.ms);
-		zfree_srcline(&he->branch_info->srcline_from);
-		zfree_srcline(&he->branch_info->srcline_to);
+		branch_info__exit(he->branch_info);
 		zfree(&he->branch_info);
 	}
 
-- 
2.46.0.rc2.264.g509ed76dc8-goog