linux-kernel - [PATCH] perf script: Fix display inconsitency when call-graph config is used

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Date:	Mon, 16 May 2016 04:51:19 +0000
From:	He Kuang <hekuang@...wei.com>
To:	<peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
	<alexander.shishkin@...ux.intel.com>, <wangnan0@...wei.com>
CC:	<hekuang@...wei.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] perf script: Fix display inconsitency when call-graph config is used

There's a display inconsistency when 'call-graph' config event appears
in different position. The problem can be reproduced like this:

We record signal_deliver with call-graph and signal_generate without it.

  $ perf record -g -a -e signal:signal_deliver -e signal:signal_generate/call-graph=no/

  [ perf record: Captured and wrote 0.017 MB perf.data (2 samples) ]

  $ perf script

  kworker/u2:1    13 [000]  6563.875949: signal:signal_generate: sig=2 errno=0 code=128 comm=perf pid=1313 grp=1 res=0 ff61cc __send_signal+0x3ec ([kernel.kallsyms])
  perf  1313 [000]  6563.877584:  signal:signal_deliver: sig=2 errno=0 code=128 sa_handler=43115e sa_flags=14000000
              7ffff314 get_signal+0x80007f0023a4 ([kernel.kallsyms])
              7fffe358 do_signal+0x80007f002028 ([kernel.kallsyms])
              7fffa5e8 exit_to_usermode_loop+0x80007f002053 ([kernel.kallsyms])
              ...

Then we exchange the order of these two events in commandline, and keep
signal_generate without call-graph.

  $ perf record -g -a -e signal:signal_generate/call-graph=no/ -e signal:signal_deliver

  [ perf record: Captured and wrote 0.017 MB perf.data (2 samples) ]

  $ perf script

    kworker/u2:2  1314 [000]  6933.353060: signal:signal_generate: sig=2 errno=0 code=128 comm=perf pid=1321 grp=1 res=0
            perf  1321 [000]  6933.353872:  signal:signal_deliver: sig=2 errno=0 code=128 sa_handler=43115e sa_flags=14000000

This time, the callchain of the event signal_deliver disappeared. The
problem is caused by that perf only checks for the first evsel in evlist
and decides if callchain should be printed.

This patch travseres all evsels in evlist to see if any of them have
callchains, and shows the right result:

  $ perf script

  kworker/u2:2  1314 [000]  6933.353060: signal:signal_generate: sig=2 errno=0 code=128 comm=perf pid=1321 grp=1 res=0 ff61cc __send_signal+0x3ec ([kernel.kallsyms])
  perf  1321 [000]  6933.353872:  signal:signal_deliver: sig=2 errno=0 code=128 sa_handler=43115e sa_flags=14000000
              7ffff314 get_signal+0x80007f0023a4 ([kernel.kallsyms])
              7fffe358 do_signal+0x80007f002028 ([kernel.kallsyms])
              7fffa5e8 exit_to_usermode_loop+0x80007f002053 ([kernel.kallsyms])
              ...

Signed-off-by: He Kuang <hekuang@...wei.com>
---
 tools/perf/builtin-script.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index efca816..7a18b92 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -339,7 +339,7 @@ static void set_print_ip_opts(struct perf_event_attr *attr)
  */
 static int perf_session__check_output_opt(struct perf_session *session)
 {
-	int j;
+	unsigned int j;
 	struct perf_evsel *evsel;
 
 	for (j = 0; j < PERF_TYPE_MAX; ++j) {
@@ -388,17 +388,20 @@ static int perf_session__check_output_opt(struct perf_session *session)
 		struct perf_event_attr *attr;
 
 		j = PERF_TYPE_TRACEPOINT;
-		evsel = perf_session__find_first_evtype(session, j);
-		if (evsel == NULL)
-			goto out;
 
-		attr = &evsel->attr;
+		evlist__for_each(session->evlist, evsel) {
+			if (evsel->attr.type != j)
+				continue;
+
+			attr = &evsel->attr;
 
-		if (attr->sample_type & PERF_SAMPLE_CALLCHAIN) {
-			output[j].fields |= PERF_OUTPUT_IP;
-			output[j].fields |= PERF_OUTPUT_SYM;
-			output[j].fields |= PERF_OUTPUT_DSO;
-			set_print_ip_opts(attr);
+			if (attr->sample_type & PERF_SAMPLE_CALLCHAIN) {
+				output[j].fields |= PERF_OUTPUT_IP;
+				output[j].fields |= PERF_OUTPUT_SYM;
+				output[j].fields |= PERF_OUTPUT_DSO;
+				set_print_ip_opts(attr);
+				goto out;
+			}
 		}
 	}
 
-- 
1.8.5.2