perf pmus: Add function to return count of core PMUs

Add perf_pmus__num_core_pmus that will count core PMUs holding the
result in a static. Reuse for perf_pmus__num_mem_pmus.

Reviewed-by: Kan Liang <[e-mail]>
Signed-off-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ali Saidi <[e-mail]>
Cc: Athira Rajeev <[e-mail]>
Cc: Dmitrii Dolgov <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jing Zhang <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: Kajol Jain <[e-mail]>
Cc: Kang Minchul <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Madhavan Srinivasan <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Mike Leach <[e-mail]>
Cc: Ming Wang <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Cc: Rob Herring <[e-mail]>
Cc: Sandipan Das <[e-mail]>
Cc: Sean Christopherson <[e-mail]>
Cc: Suzuki Poulouse <[e-mail]>
Cc: Thomas Richter <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Xing Zhengjun <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/pmus.c

···
 
 int perf_pmus__num_mem_pmus(void)
 {
-	struct perf_pmu *pmu = NULL;
-	int count = 0;
-
 	/* All core PMUs are for mem events. */
-	while ((pmu = perf_pmus__scan_core(pmu)) != NULL)
-		count++;
-
-	return count;
+	return perf_pmus__num_core_pmus();
 }
 
 /** Struct for ordering events as output in perf list. */
···
 		hybrid_scanned = true;
 	}
 	return has_hybrid;
+}
+
+int perf_pmus__num_core_pmus(void)
+{
+	static int count;
+
+	if (!count) {
+		struct perf_pmu *pmu = NULL;
+
+		while ((pmu = perf_pmus__scan_core(pmu)) != NULL)
+			count++;
+	}
+	return count;
 }
 
 struct perf_pmu *evsel__find_pmu(const struct evsel *evsel)

tools/perf/util/pmus.h

···
 void perf_pmus__print_pmu_events(const struct print_callbacks *print_cb, void *print_state);
 bool perf_pmus__have_event(const char *pname, const char *name);
 bool perf_pmus__has_hybrid(void);
+int perf_pmus__num_core_pmus(void);
 
 #endif /* __PMUS_H */