[PATCH 2/2] perf script: Don't disable use_callchain if input is pipe

[He Kuang <hekuang@huawei.com>]

Because perf data from pipe do not have a header with evsel attr, we
should not check that and disable symbol_conf.use_callchain. Otherwise,
perf script won't show callchains even if the data stream contains
callchain.

Before:
  $ perf record -g -o - uname |perf script
  Linux
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  uname  1828 182630.186578:  250000 cpu-clock:  ..b9499 setup_arg_pages
  uname  1828 182630.186850:  250000 cpu-clock:  ..83b20 ___might_sleep
  uname  1828 182630.187153:  250000 cpu-clock:  ..4b6be file_map_prot_ch
  ...

After:
  $ perf record -g -o - uname |perf script
  Linux
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  uname  1833 182675.927099:     250000 cpu-clock:
                  ba5520 _raw_spin_lock+0xfe200040 ([kernel.kallsyms])
                  389dd4 expand_downwards+0xfe200154 ([kernel.kallsyms])
                  389f34 expand_stack+0xfe200024 ([kernel.kallsyms])
                  3b957e setup_arg_pages+0xfe20019e ([kernel.kallsyms])
                  40c80f load_elf_binary+0xfe20042f ([kernel.kallsyms])
                  ...

Signed-off-by: He Kuang <hekuang@huawei.com>
---
 tools/perf/builtin-script.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index d47aef9..ec8df8f 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -371,14 +371,16 @@ static int perf_session__check_output_opt(struct perf_session *session)
 
 	if (!no_callchain) {
 		bool use_callchain = false;
+		bool not_pipe = false;
 
 		evlist__for_each_entry(session->evlist, evsel) {
+			not_pipe = true;
 			if (evsel->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
 				use_callchain = true;
 				break;
 			}
 		}
-		if (!use_callchain)
+		if (not_pipe && !use_callchain)
 			symbol_conf.use_callchain = false;
 	}
 
-- 
1.8.5.2