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

Thomas Richter
2021-05-17T14:11:28Z

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@linux.ibm.com>
Acked-By: Sumanth Korikkar <sumanthk@linux.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