[PATCH v3 04/35] libperf cpumap: Add "any CPU"/dummy test function

[Ian Rogers <irogers@google.com>]

It is common in the code currently to test a map for "empty" when in
fact the "any CPU"/dummy value of -1 is being sought. Add a new
function to enable this and document the behavior of two other
functions. The term "any CPU" comes from perf_event_open, where the
value is consumed, but it is more typical in the code to see this
value/map referred to as the dummy value. This could be misleading due
to the dummy event and also dummy not being intention revealing, so it
is hoped to migrate the code to referring to this as "any CPU".

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/lib/perf/cpumap.c              |  5 +++++
 tools/lib/perf/include/perf/cpumap.h | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
index 48595a3ad69c..7c8237a9e902 100644
--- a/tools/lib/perf/cpumap.c
+++ b/tools/lib/perf/cpumap.c
@@ -342,6 +342,11 @@ bool perf_cpu_map__equal(const struct perf_cpu_map *lhs, const struct perf_cpu_m
 	return true;
 }
 
+bool perf_cpu_map__has_any_cpu(const struct perf_cpu_map *map)
+{
+	return map && perf_cpu_map__cpu(map, 0).cpu == -1;
+}
+
 struct perf_cpu perf_cpu_map__max(const struct perf_cpu_map *map)
 {
 	struct perf_cpu result = {
diff --git a/tools/lib/perf/include/perf/cpumap.h b/tools/lib/perf/include/perf/cpumap.h
index d0ae9552f8e2..3b7c965a17f2 100644
--- a/tools/lib/perf/include/perf/cpumap.h
+++ b/tools/lib/perf/include/perf/cpumap.h
@@ -13,6 +13,9 @@ struct perf_cpu {
 
 struct perf_cpu_map;
 
+/**
+ * perf_cpu_map__dummy_new - a map with a singular "any CPU"/dummy -1 value.
+ */
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__dummy_new(void);
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__default_new(void);
 LIBPERF_API struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list);
@@ -25,11 +28,18 @@ LIBPERF_API struct perf_cpu_map *perf_cpu_map__intersect(struct perf_cpu_map *or
 LIBPERF_API void perf_cpu_map__put(struct perf_cpu_map *map);
 LIBPERF_API struct perf_cpu perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx);
 LIBPERF_API int perf_cpu_map__nr(const struct perf_cpu_map *cpus);
+/**
+ * perf_cpu_map__empty - is map either empty or the "any CPU"/dummy value.
+ */
 LIBPERF_API bool perf_cpu_map__empty(const struct perf_cpu_map *map);
 LIBPERF_API struct perf_cpu perf_cpu_map__max(const struct perf_cpu_map *map);
 LIBPERF_API bool perf_cpu_map__has(const struct perf_cpu_map *map, struct perf_cpu cpu);
 LIBPERF_API bool perf_cpu_map__equal(const struct perf_cpu_map *lhs,
 				     const struct perf_cpu_map *rhs);
+/**
+ * perf_cpu_map__any_cpu - Does the map contain the "any CPU"/dummy -1 value?
+ */
+LIBPERF_API bool perf_cpu_map__has_any_cpu(const struct perf_cpu_map *map);
 
 #define perf_cpu_map__for_each_cpu(cpu, idx, cpus)		\
 	for ((idx) = 0, (cpu) = perf_cpu_map__cpu(cpus, idx);	\
-- 
2.40.1.698.g37aff9b760-goog