perf pmu: Don't double count common sysfs and json events

After pmu_add_cpu_aliases() is called, perf_pmu__num_events() returns an
incorrect value that double counts common events and doesn't match the
actual count of events in the alias list. This is because after
'cpu_aliases_added == true', the number of events returned is
'sysfs_aliases + cpu_json_aliases'. But when adding 'case
EVENT_SRC_SYSFS' events, 'sysfs_aliases' and 'cpu_json_aliases' are both
incremented together, failing to account that these ones overlap and
only add a single item to the list. Fix it by adding another counter for
overlapping events which doesn't influence 'cpu_json_aliases'.

There doesn't seem to be a current issue because it's used in perf list
before pmu_add_cpu_aliases() so the correct value is returned. Other
uses in tests may also miss it for other reasons like only looking at
uncore events. However it's marked as a fixes commit in case any new fix
with new uses of perf_pmu__num_events() is backported.

Fixes: d9c5f5f94c2d ("perf pmu: Count sys and cpuid JSON events separately")
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250226104111.564443-3-james.clark@linaro.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index e51c17b1ea3590ea5c5b3b1ced71490abc851072..57450c73fb63303bca6a35e3e34ddaef20f42556 100644 (file)
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -595,7 +595,7 @@ static int perf_pmu__new_alias(struct perf_pmu *pmu, const char *name,
                        };
                        if (pmu_events_table__find_event(pmu->events_table, pmu, name,
                                                         update_alias, &data) == 0)
-                               pmu->cpu_json_aliases++;
+                               pmu->cpu_common_json_aliases++;
                }
                pmu->sysfs_aliases++;
                break;
@@ -1880,9 +1880,10 @@ size_t perf_pmu__num_events(struct perf_pmu *pmu)
        if (pmu->cpu_aliases_added)
                 nr += pmu->cpu_json_aliases;
        else if (pmu->events_table)
-               nr += pmu_events_table__num_events(pmu->events_table, pmu) - pmu->cpu_json_aliases;
+               nr += pmu_events_table__num_events(pmu->events_table, pmu) -
+                       pmu->cpu_common_json_aliases;
        else
-               assert(pmu->cpu_json_aliases == 0);
+               assert(pmu->cpu_json_aliases == 0 && pmu->cpu_common_json_aliases == 0);
 
        if (perf_pmu__is_tool(pmu))
                nr -= tool_pmu__num_skip_events();

diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index f5306428c03f6a9e4e1f080a440b3dd003e3db76..b93014cc3670e8216757b39c2c832f96a4cdd113 100644 (file)
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -136,6 +136,11 @@ struct perf_pmu {
        uint32_t cpu_json_aliases;
        /** @sys_json_aliases: Number of json event aliases loaded matching the PMU's identifier. */
        uint32_t sys_json_aliases;
+       /**
+        * @cpu_common_json_aliases: Number of json events that overlapped with sysfs when
+        * loading all sysfs events.
+        */
+       uint32_t cpu_common_json_aliases;
        /** @sysfs_aliases_loaded: Are sysfs aliases loaded from disk? */
        bool sysfs_aliases_loaded;
        /**