On 20/01/2021 16:40, Ian Rogers wrote:
On Wed, Jan 20, 2021 at 8:23 AM John Garry <john.garry@huawei.com mailto:john.garry@huawei.com> wrote:
Metrics containing duration_time cause a segfault: $./perf stat -v -M L1D_Cache_Fill_BW sleep 1 Using CPUID GenuineIntel-6-3D-4 metric expr 64 * l1d.replacement / 1000000000 / duration_time for L1D_Cache_Fill_BW found event duration_time found event l1d.replacement adding {l1d.replacement}:W,duration_time l1d.replacement -> cpu/umask=0x1,(null)=0x1e8483,event=0x51/ Segmentation fault In commit c2337d67199a ("perf metricgroup: Fix metrics using aliases covering multiple PMUs"), the logic in find_evsel_group() when iter'ing events was changed to not only select events in same group, but also for aliased PMUs. Checking whether events were for aliased PMUs was done by comparing the event PMU name. This was not safe for duration_time event, which has no associated PMU (and no PMU name), so fix by checking if the event PMU name is set also.Thanks for this, it should be fairly easy to add a test. Could we do this?
I don't mind following up with that.
Fixes: c2337d67199a ("perf metricgroup: Fix metrics using aliases covering multiple PMUs") Reported-by: Joakim Zhang <qiangqing.zhang@nxp.com <mailto:qiangqing.zhang@nxp.com>> Signed-off-by: John Garry <john.garry@huawei.com <mailto:john.garry@huawei.com>> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c index 2e60ee170abc..e6d3452031e5 100644 --- a/tools/perf/util/metricgroup.c +++ b/tools/perf/util/metricgroup.c @@ -162,6 +162,14 @@ static bool contains_event(struct evsel **metric_events, int num_events, return false; } +static bool evsel_same_pmu(struct evsel *ev1, struct evsel *ev2) +{ + if (!ev1->pmu_name || !ev2->pmu_name) + return false;What about the case of "!ev1->pmu_name && !ev2->pmu_name" ?
As far as I know, it should not happen, since duration_time is a special event. More below.
Thanks, Ian
+ + return !strcmp(ev1->pmu_name, ev2->pmu_name); +} + /** * Find a group of events in perf_evlist that correspond to those from a parsed * metric expression. Note, as find_evsel_group is called in the same order as @@ -280,8 +288,7 @@ static struct evsel *find_evsel_group(struct evlist *perf_evlist, */ if (!has_constraint && ev->leader != metric_events[i]->leader && - !strcmp(ev->leader->pmu_name, - metric_events[i]->leader->pmu_name)) + evsel_same_pmu(ev->leader, metric_events[i]->leader))
ev->leader->pmu_name == NULL for only duration_time event. And we don't get here for ev == metric_events[i] == duration_time event (as we use evlist__for_each_entry_continue() and duration_time is always last in metric_events[]), so both event arguments should not have pmu_name == NULL. Indeed, I could just check metric_events[i]->leader->pmu_name != NULL, but thought it better to check both for safety.
Cheers, John
break; if (!strcmp(metric_events[i]->name, ev->name)) { set_bit(ev->idx, evlist_used); -- 2.26.2