libperf evlist: Allow mixing per-thread and per-cpu mmaps

mmap_per_evsel() will skip events that do not match the CPU, so all CPUs
can be iterated in any case.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20220524075436.29144-11-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/perf/evlist.c

@@ -512,29 +512,6 @@ mmap_per_evsel(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
 	return 0;
 }
 
-static int
-mmap_per_thread(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
-		struct perf_mmap_param *mp)
-{
-	int thread;
-	int nr_threads = perf_thread_map__nr(evlist->threads);
-
-	for (thread = 0; thread < nr_threads; thread++) {
-		int output = -1;
-		int output_overwrite = -1;
-
-		if (mmap_per_evsel(evlist, ops, thread, mp, 0, thread,
-				   &output, &output_overwrite))
-			goto out_unmap;
-	}
-
-	return 0;
-
-out_unmap:
-	perf_evlist__munmap(evlist);
-	return -1;
-}
-
 static int
 mmap_per_cpu(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
 	     struct perf_mmap_param *mp)
@@ -565,9 +542,14 @@ static int perf_evlist__nr_mmaps(struct perf_evlist *evlist)
 {
 	int nr_mmaps;
 
+	/* One for each CPU */
 	nr_mmaps = perf_cpu_map__nr(evlist->all_cpus);
-	if (perf_cpu_map__empty(evlist->all_cpus))
-		nr_mmaps = perf_thread_map__nr(evlist->threads);
+	if (perf_cpu_map__empty(evlist->all_cpus)) {
+		/* Plus one for each thread */
+		nr_mmaps += perf_thread_map__nr(evlist->threads);
+		/* Minus the per-thread CPU (-1) */
+		nr_mmaps -= 1;
+	}
 
 	return nr_mmaps;
 }
@@ -577,7 +559,6 @@ int perf_evlist__mmap_ops(struct perf_evlist *evlist,
 			  struct perf_mmap_param *mp)
 {
 	struct perf_evsel *evsel;
-	const struct perf_cpu_map *cpus = evlist->all_cpus;
 
 	if (!ops || !ops->get || !ops->mmap)
 		return -EINVAL;
@@ -596,9 +577,6 @@ int perf_evlist__mmap_ops(struct perf_evlist *evlist,
 	if (evlist->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
 		return -ENOMEM;
 
-	if (perf_cpu_map__empty(cpus))
-		return mmap_per_thread(evlist, ops, mp);
-
 	return mmap_per_cpu(evlist, ops, mp);
 }