perf cpumap: Add is_subset function

Returns true if the second argument is a subset of the first.

Signed-off-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Antonov <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Alexei Starovoitov <[e-mail]>
Cc: Alexey Bayduraev <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Andrii Nakryiko <[e-mail]>
Cc: Daniel Borkmann <[e-mail]>
Cc: German Gomez <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: John Fastabend <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: KP Singh <[e-mail]>
Cc: Kajol Jain <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Martin KaFai Lau <[e-mail]>
Cc: Mathieu Poirier <[e-mail]>
Cc: Mike Leach <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Riccardo Mancini <[e-mail]>
Cc: Song Liu <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: Suzuki Poulouse <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Yonghong Song <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/perf/cpumap.c

···
 	return map->nr > 0 ? map->map[map->nr - 1] : result;
 }
 
+/** Is 'b' a subset of 'a'. */
+bool perf_cpu_map__is_subset(const struct perf_cpu_map *a, const struct perf_cpu_map *b)
+{
+	if (a == b || !b)
+		return true;
+	if (!a || b->nr > a->nr)
+		return false;
+
+	for (int i = 0, j = 0; i < a->nr; i++) {
+		if (a->map[i].cpu > b->map[j].cpu)
+			return false;
+		if (a->map[i].cpu == b->map[j].cpu) {
+			j++;
+			if (j == b->nr)
+				return true;
+		}
+	}
+	return false;
+}
+
 /*
  * Merge two cpumaps
  *

tools/lib/perf/include/internal/cpumap.h

···
 #endif
 
 int perf_cpu_map__idx(const struct perf_cpu_map *cpus, struct perf_cpu cpu);
+bool perf_cpu_map__is_subset(const struct perf_cpu_map *a, const struct perf_cpu_map *b);
 
 #endif /* __LIBPERF_INTERNAL_CPUMAP_H */