Messages in this thread | | | From | Namhyung Kim <> | Date | Tue, 15 Sep 2020 23:39:56 +0900 | Subject | Re: [PATCH 04/11] perf parse-event: Fix cpu map leaks |
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Hi Arnaldo,
On Tue, Sep 15, 2020 at 9:18 PM Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > Em Tue, Sep 15, 2020 at 12:18:12PM +0900, Namhyung Kim escreveu: > > Like evlist cpu map, evsel's cpu map should have proper refcount by > > releasing the original count after creation. > > "releasing original count after creation"? > > There are two fixes here, one its legit, i.e. when failing to create > the new evsel, if you created the perf_cpu_map, drop the refcount, > which, in this case, will free it since perf_cpu_map__new() sets it to > 1. > > But what about the other? Humm, I see, since a new refcount is being > obtained, then we need to drop the first. > > This all got complicated, perhaps the following patch is simpler? > > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c > index c4d2394e2b2dc60f..3dceeacf8669bc5d 100644 > --- a/tools/perf/util/parse-events.c > +++ b/tools/perf/util/parse-events.c > @@ -353,18 +353,20 @@ __add_event(struct list_head *list, int *idx, > const char *cpu_list) > { > struct evsel *evsel; > - struct perf_cpu_map *cpus = pmu ? pmu->cpus : > + struct perf_cpu_map *cpus = pmu ? perf_cpu_map__get(pmu->cpus) : > cpu_list ? perf_cpu_map__new(cpu_list) : NULL; > > if (init_attr) > event_attr_init(attr); > > evsel = evsel__new_idx(attr, *idx); > - if (!evsel) > + if (!evsel) { > + perf_cpu_map__put(cpus); > return NULL; > + } > > (*idx)++; > - evsel->core.cpus = perf_cpu_map__get(cpus); > + evsel->core.cpus = cpus; > evsel->core.own_cpus = perf_cpu_map__get(cpus); > evsel->core.system_wide = pmu ? pmu->is_uncore : false; > evsel->auto_merge_stats = auto_merge_stats; > > > --- > > I.e. if we're going to share pmu->cpus, grab the necessary refcount at > that point, if we're going to create one (pmu == NULL), then > perf_cpu_map__new() will have the refcount we need (will set it to 1). > > Then, if we fail to create the new evsel, we just drop the refcount we > got either from perf_cpu_map__get(pmu->cpus) or from > perf_cpu_map__new(cpu_list) (NULL is ok for __put() operations, that > covers that last ': NULL'). > > And then, when we go make evsel->core.cpus share that cpu_map, we know > we have the necessary refcount already, right?
Indeed! This looks a lot better. Do you want me to resend?
Thanks Namhyung
> > No need to later on drop the one obtained previously via: > > evsel->core.cpus = perf_cpu_map__get(cpus); > > And we don't need to drop it later when we want to drop the extra > refcount it gets when pmu == NULL. > > - Arnaldo
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