libperf tests: Fix test_stat_cpu

The `cpu` argument of perf_evsel__read() must specify the cpu index.

perf_cpu_map__for_each_cpu() is for iterating the cpu number (not index)
and is thus not appropriate for use with perf_evsel__read().

So, if there is an offline CPU, the cpu number specified in the argument
may point out of range because the cpu number and the cpu index are
different.

Fix test_stat_cpu().

Testing it:

  # make tests -C tools/lib/perf/
  make: Entering directory '/home/nakamura/kernel_src/linux-5.15-rc4_fix/tools/lib/perf'
  running static:
  - running tests/test-cpumap.c...OK
  - running tests/test-threadmap.c...OK
  - running tests/test-evlist.c...OK
  - running tests/test-evsel.c...OK
  running dynamic:
  - running tests/test-cpumap.c...OK
  - running tests/test-threadmap.c...OK
  - running tests/test-evlist.c...OK
  - running tests/test-evsel.c...OK
  make: Leaving directory '/home/nakamura/kernel_src/linux-5.15-rc4_fix/tools/lib/perf'
Signed-off-by: Shunsuke Nakamura <nakamura.shun@fujitsu.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20211011083704.4108720-1-nakamura.shun@fujitsu.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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

@@ -40,7 +40,7 @@ static int test_stat_cpu(void)
 		.type	= PERF_TYPE_SOFTWARE,
 		.config	= PERF_COUNT_SW_TASK_CLOCK,
 	};
-	int err, cpu, tmp;
+	int err, idx;
 
 	cpus = perf_cpu_map__new(NULL);
 	__T("failed to create cpus", cpus);
@@ -70,10 +70,10 @@ static int test_stat_cpu(void)
 	perf_evlist__for_each_evsel(evlist, evsel) {
 		cpus = perf_evsel__cpus(evsel);
 
-		perf_cpu_map__for_each_cpu(cpu, tmp, cpus) {
+		for (idx = 0; idx < perf_cpu_map__nr(cpus); idx++) {
 			struct perf_counts_values counts = { .val = 0 };
 
-			perf_evsel__read(evsel, cpu, 0, &counts);
+			perf_evsel__read(evsel, idx, 0, &counts);
 			__T("failed to read value for evsel", counts.val != 0);
 		}
 	}

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

@@ -22,7 +22,7 @@ static int test_stat_cpu(void)
 		.type	= PERF_TYPE_SOFTWARE,
 		.config	= PERF_COUNT_SW_CPU_CLOCK,
 	};
-	int err, cpu, tmp;
+	int err, idx;
 
 	cpus = perf_cpu_map__new(NULL);
 	__T("failed to create cpus", cpus);
@@ -33,10 +33,10 @@ static int test_stat_cpu(void)
 	err = perf_evsel__open(evsel, cpus, NULL);
 	__T("failed to open evsel", err == 0);
 
-	perf_cpu_map__for_each_cpu(cpu, tmp, cpus) {
+	for (idx = 0; idx < perf_cpu_map__nr(cpus); idx++) {
 		struct perf_counts_values counts = { .val = 0 };
 
-		perf_evsel__read(evsel, cpu, 0, &counts);
+		perf_evsel__read(evsel, idx, 0, &counts);
 		__T("failed to read value for evsel", counts.val != 0);
 	}