libperf: Add perf_evsel__enable/disable test

Add simple perf_evsel enable/disable test together with evsel counter
reading interface.

Committer testing:

# make -C tools/perf/lib tests
make: Entering directory '/home/acme/git/perf/tools/perf/lib'
LINK test-cpumap-a
LINK test-threadmap-a
LINK test-evlist-a
LINK test-evsel-a
LINK test-cpumap-so
LINK test-threadmap-so
LINK test-evlist-so
LINK test-evsel-so
running static:
- running test-cpumap.c...OK
- running test-threadmap.c...OK
- running test-evlist.c...OK
- running test-evsel.c...OK
running dynamic:
- running test-cpumap.c...OK
- running test-threadmap.c...OK
- running test-evlist.c...OK
- running test-evsel.c...OK
make: Leaving directory '/home/acme/git/perf/tools/perf/lib'
#

Signed-off-by: Jiri Olsa <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Alexey Budankov <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Michael Petlan <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/lib/tests/test-evsel.c

···
 	return 0;
 }
 
+static int test_stat_thread_enable(void)
+{
+	struct perf_counts_values counts = { .val = 0 };
+	struct perf_thread_map *threads;
+	struct perf_evsel *evsel;
+	struct perf_event_attr attr = {
+		.type	  = PERF_TYPE_SOFTWARE,
+		.config	  = PERF_COUNT_SW_TASK_CLOCK,
+		.disabled = 1,
+	};
+	int err;
+
+	threads = perf_thread_map__new_dummy();
+	__T("failed to create threads", threads);
+
+	perf_thread_map__set_pid(threads, 0, 0);
+
+	evsel = perf_evsel__new(&attr);
+	__T("failed to create evsel", evsel);
+
+	err = perf_evsel__open(evsel, NULL, threads);
+	__T("failed to open evsel", err == 0);
+
+	perf_evsel__read(evsel, 0, 0, &counts);
+	__T("failed to read value for evsel", counts.val == 0);
+
+	err = perf_evsel__enable(evsel);
+	__T("failed to enable evsel", err == 0);
+
+	perf_evsel__read(evsel, 0, 0, &counts);
+	__T("failed to read value for evsel", counts.val != 0);
+
+	err = perf_evsel__disable(evsel);
+	__T("failed to enable evsel", err == 0);
+
+	perf_evsel__close(evsel);
+	perf_evsel__delete(evsel);
+
+	perf_thread_map__put(threads);
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	__T_START;
 
 	test_stat_cpu();
 	test_stat_thread();
+	test_stat_thread_enable();
 
 	__T_OK;
 	return 0;