linux-kernel - [PATCH 03/19] perf c2c: Fix display bug when using pipe

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Date:   Tue, 14 Mar 2017 15:50:07 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>, kernel-team@....com,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 03/19] perf c2c: Fix display bug when using pipe

From: Namhyung Kim <namhyung@...nel.org>

Currently 'perf c2c report' determines display mode using the --stdio
option, but it could be a problem if stdout is not a tty since
setup_browser falls back to stdio in this case.

But perf c2c didn't know this and tried to use TUI browser anyway.  It
should check "use_browser" variable instead.

For example, the following command showed nothing and broke terminal
setting.  Now it's fixed..

  $ perf c2c report | head
  =================================================
              Trace Event Information
  =================================================
    Total records                     :        136
    Locked Load/Store Operations      :          6
    Load Operations                   :         62
    Loads - uncacheable               :          0
    Loads - IO                        :          1
    Loads - Miss                      :          7
    Loads - no mapping                :          2

Committer notes:

When trying it without a proper perf.data file it results in a stuck
terminal, just as Namhyung reported above:

  [acme@...et ~]$ perf c2c report | head
  WARNING: no sample cpu value[acme@...et ~]$

One has to kill it from some other xterm. Confirm that this patch fixes
it:

After:

  $ perf c2c report | head
  WARNING: no sample cpu value=================================================
              Trace Event Information
  =================================================
    Total records                     :         14
    Locked Load/Store Operations      :          0
    Load Operations                   :          0
    Loads - uncacheable               :          0
    Loads - IO                        :          0
    Loads - Miss                      :          0
    Loads - no mapping                :          0
  $

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Acked-by: Jiri Olsa <jolsa@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: kernel-team@....com
Link: http://lkml.kernel.org/r/20170307150851.22304-6-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-c2c.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index 3fac30ed92f1..5cd6d7a047b9 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -2334,7 +2334,7 @@ static int perf_c2c__hists_browse(struct hists *hists)
 
 static void perf_c2c_display(struct perf_session *session)
 {
-	if (c2c.use_stdio)
+	if (use_browser == 0)
 		perf_c2c__hists_fprintf(stdout, session);
 	else
 		perf_c2c__hists_browse(&c2c.hists.hists);
-- 
2.9.3