[PATCH] perf report: Fix a bug on "--call-graph none" option

From: Namhyung Kim
Date: Wed Sep 30 2015 - 00:48:20 EST

The patch f9db0d0f1b2c ("perf callchain: Allow disabling call graphs
per event") added an ability to enable/disable callchain recording per
event. But it had a problem when the enablement setting is changed at
'perf report' time using -g/--call-graph option.

For example, the following scenario will get a segfault.

$ perf record -ag sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.500 MB perf.data (2555 samples) ]

$ perf report -g none
perf: Segmentation fault
-------- backtrace --------

This is because callchain_param.sort() callback was not set but it
tried to call the function as it had the PERF_SAMPLE_CALLCHAIN bit.

Cc: Kan Liang <kan.liang@xxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
tools/perf/util/hist.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index b3567a25f0c4..99b8e14ce010 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -1149,7 +1149,7 @@ void hists__output_resort(struct hists *hists, struct ui_progress *prog)
struct perf_evsel *evsel = hists_to_evsel(hists);
bool use_callchain;

- if (evsel && !symbol_conf.show_ref_callgraph)
+ if (evsel && symbol_conf.use_callchain && !symbol_conf.show_ref_callgraph)
use_callchain = evsel->attr.sample_type & PERF_SAMPLE_CALLCHAIN;
use_callchain = symbol_conf.use_callchain;

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