Patch "perf evlist: Add evlist__add_dummy_on_all_cpus()" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    perf evlist: Add evlist__add_dummy_on_all_cpus()

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-evlist-add-evlist__add_dummy_on_all_cpus.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a4455e5be294c717c5f1b67c1ef9471f3229e41f
Author: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Date:   Tue May 24 10:54:26 2022 +0300

    perf evlist: Add evlist__add_dummy_on_all_cpus()
    
    [ Upstream commit 126d68fdcabed8c2ca5ffaba785add93ef722da8 ]
    
    Add evlist__add_dummy_on_all_cpus() to enable creating a system-wide dummy
    event that sets up the system-wide maps before map propagation.
    
    For convenience, add evlist__add_aux_dummy() so that the logic can be used
    whether or not the event needs to be system-wide.
    
    Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
    Acked-by: Ian Rogers <irogers@xxxxxxxxxx>
    Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
    Cc: Alexey Bayduraev <alexey.v.bayduraev@xxxxxxxxxxxxxxx>
    Cc: Ian Rogers <irogers@xxxxxxxxxx>
    Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
    Cc: Leo Yan <leo.yan@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220524075436.29144-6-adrian.hunter@xxxxxxxxx
    Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
    Stable-dep-of: f9cdeb58a9cf ("perf evlist: Avoid frequency mode for the dummy event")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 39d294f6c3218..a75cdcf381308 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -258,6 +258,51 @@ int evlist__add_dummy(struct evlist *evlist)
 	return 0;
 }
 
+static void evlist__add_on_all_cpus(struct evlist *evlist, struct evsel *evsel)
+{
+	evsel->core.system_wide = true;
+
+	/*
+	 * All CPUs.
+	 *
+	 * Note perf_event_open() does not accept CPUs that are not online, so
+	 * in fact this CPU list will include only all online CPUs.
+	 */
+	perf_cpu_map__put(evsel->core.own_cpus);
+	evsel->core.own_cpus = perf_cpu_map__new(NULL);
+	perf_cpu_map__put(evsel->core.cpus);
+	evsel->core.cpus = perf_cpu_map__get(evsel->core.own_cpus);
+
+	/* No threads */
+	perf_thread_map__put(evsel->core.threads);
+	evsel->core.threads = perf_thread_map__new_dummy();
+
+	evlist__add(evlist, evsel);
+}
+
+struct evsel *evlist__add_aux_dummy(struct evlist *evlist, bool system_wide)
+{
+	struct evsel *evsel = evlist__dummy_event(evlist);
+
+	if (!evsel)
+		return NULL;
+
+	evsel->core.attr.exclude_kernel = 1;
+	evsel->core.attr.exclude_guest = 1;
+	evsel->core.attr.exclude_hv = 1;
+	evsel->core.attr.freq = 0;
+	evsel->core.attr.sample_period = 1;
+	evsel->no_aux_samples = true;
+	evsel->name = strdup("dummy:u");
+
+	if (system_wide)
+		evlist__add_on_all_cpus(evlist, evsel);
+	else
+		evlist__add(evlist, evsel);
+
+	return evsel;
+}
+
 static int evlist__add_attrs(struct evlist *evlist, struct perf_event_attr *attrs, size_t nr_attrs)
 {
 	struct evsel *evsel, *n;
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index ec177f783ee67..decf5c944adba 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -112,6 +112,11 @@ int __evlist__add_default_attrs(struct evlist *evlist,
 int arch_evlist__add_default_attrs(struct evlist *evlist);
 
 int evlist__add_dummy(struct evlist *evlist);
+struct evsel *evlist__add_aux_dummy(struct evlist *evlist, bool system_wide);
+static inline struct evsel *evlist__add_dummy_on_all_cpus(struct evlist *evlist)
+{
+	return evlist__add_aux_dummy(evlist, true);
+}
 
 int evlist__add_sb_event(struct evlist *evlist, struct perf_event_attr *attr,
 			 evsel__sb_cb_t cb, void *data);