linux-kernel - [tip:perf/core] perf test attr: Fix python error on empty result

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Date:   Tue, 3 Oct 2017 09:43:52 -0700
From:   tip-bot for Thomas Richter <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     heiko.carstens@...ibm.com, hpa@...or.com,
        brueckner@...ux.vnet.ibm.com, tglx@...utronix.de, mingo@...nel.org,
        linux-kernel@...r.kernel.org, tmricht@...ux.vnet.ibm.com,
        jolsa@...nel.org, schwidefsky@...ibm.com, acme@...hat.com
Subject: [tip:perf/core] perf test attr: Fix python error on empty result

Commit-ID:  3440fe2790aa3d13530260af6033533b18959aee
Gitweb:     https://git.kernel.org/tip/3440fe2790aa3d13530260af6033533b18959aee
Author:     Thomas Richter <tmricht@...ux.vnet.ibm.com>
AuthorDate: Wed, 13 Sep 2017 10:12:08 +0200
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Mon, 2 Oct 2017 14:00:20 -0300

perf test attr: Fix python error on empty result

Commit d78ada4a767 ("perf tests attr: Do not store failed events") does
not create an event file in the /tmp directory when the
perf_open_event() system call failed.

This can lead to a situation where not /tmp/event-xx-yy-zz result file
exists at all (for example on a s390x virtual machine environment) where
no CPUMF hardware is available.

The following command then fails with a python call back chain instead
of printing failure:

  [root@...60046 perf]# /usr/bin/python2 ./tests/attr.py -d ./tests/attr/ \
      -p ./perf -v -ttest-stat-basic
  running './tests/attr//test-stat-basic'
  Traceback (most recent call last):
    File "./tests/attr.py", line 379, in <module>
      main()
    File "./tests/attr.py", line 370, in main
      run_tests(options)
    File "./tests/attr.py", line 311, in run_tests
      Test(f, options).run()
    File "./tests/attr.py", line 300, in run
      self.compare(self.expect, self.result)
    File "./tests/attr.py", line 248, in compare
      exp_event.diff(res_event)
  UnboundLocalError: local variable 'res_event' referenced before assignment
  [root@...60046 perf]#

This patch catches this pitfall and prints an error message instead:

  [root@...60047 perf]# /usr/bin/python2 ./tests/attr.py -d ./tests/attr/ \
       -p ./perf  -vvv -ttest-stat-basic
  running './tests/attr//test-stat-basic'
    loading expected events
      Event event:base-stat
        fd = 1
        group_fd = -1
        flags = 0|8
        [....]
        sample_regs_user = 0
        sample_stack_user = 0
    'PERF_TEST_ATTR=/tmp/tmpJbMQMP ./perf stat -o /tmp/tmpJbMQMP/perf.data -e cycles kill >/dev/null 2>&1' ret '1', expected '1'
    loading result events
    compare
      matching [event:base-stat]
      match: [event:base-stat] matches []
      res_event is empty
  FAILED './tests/attr//test-stat-basic' - match failure
  [root@...60047 perf]#

Signed-off-by: Thomas-Mich Richter <tmricht@...ux.vnet.ibm.com>
Acked-by: Jiri Olsa <jolsa@...nel.org>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Hendrik Brueckner <brueckner@...ux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Thomas-Mich Richter <tmricht@...ux.vnet.ibm.com>
LPU-Reference: 20170913081209.39570-1-tmricht@...ux.vnet.ibm.com
Link: http://lkml.kernel.org/n/tip-04d63nn7svfgxdhi60gq2mlm@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/tests/attr.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/attr.py b/tools/perf/tests/attr.py
index 6bb50e8..a13cd78 100644
--- a/tools/perf/tests/attr.py
+++ b/tools/perf/tests/attr.py
@@ -237,6 +237,7 @@ class Test(object):
         # events in result. Fail if there's not any.
         for exp_name, exp_event in expect.items():
             exp_list = []
+            res_event = {}
             log.debug("    matching [%s]" % exp_name)
             for res_name, res_event in result.items():
                 log.debug("      to [%s]" % res_name)
@@ -253,7 +254,10 @@ class Test(object):
                 if exp_event.optional():
                     log.debug("    %s does not match, but is optional" % exp_name)
                 else:
-                    exp_event.diff(res_event)
+                    if not res_event:
+                        log.debug("    res_event is empty");
+                    else:
+                        exp_event.diff(res_event)
                     raise Fail(self, 'match failure');
 
             match[exp_name] = exp_list