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

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

[Namhyung Kim]

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 --------
  perf[0x53a98a]
  /usr/lib/libc.so.6(+0x335af)[0x7f4e91df95af]

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@intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 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;
 	else
 		use_callchain = symbol_conf.use_callchain;
-- 
2.5.0

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

[Arnaldo Carvalho de Melo]

Em Wed, Sep 30, 2015 at 01:34:00PM +0900, Namhyung Kim escreveu:
> 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 --------
>   perf[0x53a98a]
>   /usr/lib/libc.so.6(+0x335af)[0x7f4e91df95af]
> 
> 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.

Thanks, reproduced, tested the fix, applied.

- Arnaldo

[tip:perf/core] perf report: Fix a bug on "--call-graph none" option

[tip-bot for Namhyung Kim]

Commit-ID:  208e7607459477432d3df52c32d4b961a96d4a94
Gitweb:     http://git.kernel.org/tip/208e7607459477432d3df52c32d4b961a96d4a94
Author:     Namhyung Kim <namhyung@kernel.org>
AuthorDate: Wed, 30 Sep 2015 13:34:00 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 1 Oct 2015 09:54:33 -0300

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

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 --------
  perf[0x53a98a]
  /usr/lib/libc.so.6(+0x335af)[0x7f4e91df95af]

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.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Fixes: f9db0d0f1b2c ("perf callchain: Allow disabling call graphs per event")
Link: http://lkml.kernel.org/r/1443587640-24242-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 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 0cad9e0..c346b33 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -1151,7 +1151,7 @@ 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;
 	else
 		use_callchain = symbol_conf.use_callchain;