linux-kernel - [PATCH] perf test: Test libpfm4 support (63) reports error

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Date:   Mon, 17 May 2021 16:09:31 +0200
From:   Thomas Richter <tmricht@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org, eranian@...gle.com
Cc:     svens@...ux.ibm.com, gor@...ux.ibm.com, sumanthk@...ux.ibm.com,
        hca@...ux.ibm.com, Thomas Richter <tmricht@...ux.ibm.com>
Subject: [PATCH] perf test: Test libpfm4 support (63) reports error

Compiling perf with make LIBPFM4=1 includes libpfm support and
enables test case 63 'Test libpfm4 support'. This test reports an error
on all platforms for subtest 63.2 'test groups of --pfm-events'.
The reported error message is 'nested event groups not supported'

 # ./perf test -F 63
 63: Test libpfm4 support                                            :
 63.1: test of individual --pfm-events                               :
 Error:
 failed to parse event stereolab : event not found
 Error:
 failed to parse event stereolab,instructions : event not found
 Error:
 failed to parse event instructions,stereolab : event not found
  Ok
 63.2: test groups of --pfm-events                                   :
 Error:
 nested event groups not supported    <------ Error message here
 Error:
 failed to parse event {stereolab} : event not found
 Error:
 failed to parse event {instructions,cycles},{instructions,stereolab} :\
	 event not found
 Ok
 #

This patch addresses the error message 'nested event groups not supported'.
The root cause is function parse_libpfm_events_option() which parses the
event string '{},{instructions}' and can not handle a leading empty
group notation '{},...'.

The code detects the first (empty) group indicator '{' but does not
terminate group processing on the following group closing character '}'.
So when the second group indicator '{' is detected, the code assumes
a nested group and returns an error.

With the error message fixed, also change the expected event number to
one for the test case to succeed.

While at it also fix a memory leak. In good case the function does not
free the duplicated string given as first parameter.

Output after:
 # ./perf test -F 63
 63: Test libpfm4 support                                            :
 63.1: test of individual --pfm-events                               :
 Error:
 failed to parse event stereolab : event not found
 Error:
 failed to parse event stereolab,instructions : event not found
 Error:
 failed to parse event instructions,stereolab : event not found
  Ok
 63.2: test groups of --pfm-events                                   :
 Error:
 failed to parse event {stereolab} : event not found
 Error:
 failed to parse event {instructions,cycles},{instructions,stereolab} : \
	 event not found
  Ok
 #
Error message 'nested event groups not supported' is gone.

Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
Acked-By: Sumanth Korikkar <sumanthk@...ux.ibm.com>
---
 tools/perf/tests/pfm.c |  4 ++--
 tools/perf/util/pfm.c  | 11 ++++++++++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/tools/perf/tests/pfm.c b/tools/perf/tests/pfm.c
index 76a53126efdf..d4b0ef74defc 100644
--- a/tools/perf/tests/pfm.c
+++ b/tools/perf/tests/pfm.c
@@ -131,8 +131,8 @@ static int test__pfm_group(void)
 		},
 		{
 			.events = "{},{instructions}",
-			.nr_events = 0,
-			.nr_groups = 0,
+			.nr_events = 1,
+			.nr_groups = 1,
 		},
 		{
 			.events = "{instructions},{instructions}",
diff --git a/tools/perf/util/pfm.c b/tools/perf/util/pfm.c
index d735acb6c29c..6eef6dfeaa57 100644
--- a/tools/perf/util/pfm.c
+++ b/tools/perf/util/pfm.c
@@ -62,8 +62,16 @@ int parse_libpfm_events_option(const struct option *opt, const char *str,
 		}
 
 		/* no event */
-		if (*q == '\0')
+		if (*q == '\0') {
+			if (*sep == '}') {
+				if (grp_evt < 0) {
+					ui__error("cannot close a non-existing event group\n");
+					goto error;
+				}
+				grp_evt--;
+			}
 			continue;
+		}
 
 		memset(&attr, 0, sizeof(attr));
 		event_attr_init(&attr);
@@ -107,6 +115,7 @@ int parse_libpfm_events_option(const struct option *opt, const char *str,
 			grp_evt = -1;
 		}
 	}
+	free(p_orig);
 	return 0;
 error:
 	free(p_orig);
-- 
2.31.1