Re: [PATCH v1 02/25] perf sample: Make sure perf_sample__init/exit are used

Namhyung Kim
2026-03-03T22:38:47Z

On Mon, Feb 09, 2026 at 09:40:09AM -0800, Ian Rogers wrote:
> The deferred stack trace code wasn't using perf_sample__init/exit. Add
> the deferred stack trace clean up to perf_sample__exit which requires
> proper NULL initialization in perf_sample__init. Make the
> perf_sample__exit robust to being called more than once by using
> zfree. Make the error paths in evsel__parse_sample exit the sample.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/builtin-inject.c | 6 +++++-
> tools/perf/util/evsel.c | 28 +++++++++++++++++-----------
> tools/perf/util/sample.c | 8 ++++++--
> tools/perf/util/session.c | 13 +++++++++----
> 4 files changed, 37 insertions(+), 18 deletions(-)
>
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index 5b29f4296861..3d2556213599 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -1087,6 +1087,7 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
> struct perf_sample sample_sw;
> struct perf_inject *inject = container_of(tool, struct perf_inject, tool);
> u32 pid = evsel__intval(evsel, sample, "pid");
> + int ret;
>
> list_for_each_entry(ent, &inject->samples, node) {
> if (pid == ent->tid)
> @@ -1098,12 +1099,15 @@ static int perf_inject__sched_stat(const struct perf_tool *tool,
> event_sw = &ent->event[0];
> evsel__parse_sample(evsel, event_sw, &sample_sw);
>
> + perf_sample__init(&sample_sw, /*all=*/false);

Shouldn't it be called before evsel__parse_sample()?

> sample_sw.period = sample->period;
> sample_sw.time = sample->time;
> perf_event__synthesize_sample(event_sw, evsel->core.attr.sample_type,
> evsel->core.attr.read_format, &sample_sw);
> build_id__mark_dso_hit(tool, event_sw, &sample_sw, evsel, machine);
> - return perf_event__repipe(tool, event_sw, &sample_sw, machine);
> + ret = perf_event__repipe(tool, event_sw, &sample_sw, machine);
> + perf_sample__exit(&sample_sw);
> + return ret;
> }
> #endif
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index f59228c1a39e..34ae388750db 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -3067,7 +3067,7 @@ static inline bool overflow(const void *endp, u16 max_size, const void *offset,
> #define OVERFLOW_CHECK(offset, size, max_size) \
> do { \
> if (overflow(endp, (max_size), (offset), (size))) \
> - return -EFAULT; \
> + goto out_efault; \
> } while (0)
>
> #define OVERFLOW_CHECK_u64(offset) \
> @@ -3199,6 +3199,8 @@ static int __set_offcpu_sample(struct perf_sample *data)
> data->cgroup = *array;
>
> return 0;
> +out_efault:
> + return -EFAULT;
> }
>
> int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> @@ -3217,7 +3219,7 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> */
> union u64_swap u;
>
> - memset(data, 0, sizeof(*data));
> + perf_sample__init(data, /*all=*/true);

It seems this is called before evlist__parse_sample(), do we need to do
it here as well?

> data->cpu = data->pid = data->tid = -1;
> data->stream_id = data->id = data->time = -1ULL;
> data->period = evsel->core.attr.sample_period;
> @@ -3231,25 +3233,26 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
>
> data->callchain = (struct ip_callchain *)&event->callchain_deferred.nr;
> if (data->callchain->nr > max_callchain_nr)
> - return -EFAULT;
> + goto out_efault;
>
> data->deferred_cookie = event->callchain_deferred.cookie;
>
> if (evsel->core.attr.sample_id_all)
> perf_evsel__parse_id_sample(evsel, event, data);
> +
> return 0;
> }
>
> if (event->header.type != PERF_RECORD_SAMPLE) {
> - if (!evsel->core.attr.sample_id_all)
> - return 0;
> - return perf_evsel__parse_id_sample(evsel, event, data);
> + if (evsel->core.attr.sample_id_all)
> + perf_evsel__parse_id_sample(evsel, event, data);
> + return 0;
> }
>
> array = event->sample.array;
>
> if (perf_event__check_size(event, evsel->sample_size))
> - return -EFAULT;
> + goto out_efault;
>
> if (type & PERF_SAMPLE_IDENTIFIER) {
> data->id = *array;
> @@ -3342,7 +3345,7 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> sizeof(struct sample_read_value);
>
> if (data->read.group.nr > max_group_nr)
> - return -EFAULT;
> + goto out_efault;
>
> sz = data->read.group.nr * sample_read_value_size(read_format);
> OVERFLOW_CHECK(array, sz, max_size);
> @@ -3370,7 +3373,7 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> data->callchain = (struct ip_callchain *)array++;
> callchain_nr = data->callchain->nr;
> if (callchain_nr > max_callchain_nr)
> - return -EFAULT;
> + goto out_efault;
> sz = callchain_nr * sizeof(u64);
> /*
> * Save the cookie for the deferred user callchain. The last 2
> @@ -3428,7 +3431,7 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> data->branch_stack = (struct branch_stack *)array++;
>
> if (data->branch_stack->nr > max_branch_nr)
> - return -EFAULT;
> + goto out_efault;
>
> sz = data->branch_stack->nr * sizeof(struct branch_entry);
> if (evsel__has_branch_hw_idx(evsel)) {
> @@ -3505,7 +3508,7 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> data->user_stack.size = *array++;
> if (WARN_ONCE(data->user_stack.size > sz,
> "user stack dump failure\n"))
> - return -EFAULT;
> + goto out_efault;
> }
> }
>
> @@ -3586,6 +3589,9 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> return __set_offcpu_sample(data);
>
> return 0;
> +out_efault:
> + perf_sample__exit(data);
> + return -EFAULT;
> }
>
> int evsel__parse_sample_timestamp(struct evsel *evsel, union perf_event *event,
> diff --git a/tools/perf/util/sample.c b/tools/perf/util/sample.c
> index 8f82aaf1aab6..4894b990c6ce 100644
> --- a/tools/perf/util/sample.c
> +++ b/tools/perf/util/sample.c
> @@ -21,13 +21,17 @@ void perf_sample__init(struct perf_sample *sample, bool all)
> } else {
> sample->user_regs = NULL;
> sample->intr_regs = NULL;
> + sample->deferred_callchain = false;
> + sample->callchain = NULL;
> }
> }
>
> void perf_sample__exit(struct perf_sample *sample)
> {
> - free(sample->user_regs);
> - free(sample->intr_regs);
> + zfree(&sample->user_regs);
> + zfree(&sample->intr_regs);
> + if (sample->deferred_callchain)
> + zfree(&sample->callchain);

Nit: maybe better to set deferred_callchain to false.

Thanks,
Namhyung

> }
>
> struct regs_dump *perf_sample__user_regs(struct perf_sample *sample)
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 4b465abfa36c..c48e840da7d4 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1367,14 +1367,18 @@ static int evlist__deliver_deferred_callchain(struct evlist *evlist,
> list_for_each_entry_safe(de, tmp, &evlist->deferred_samples, list) {
> struct perf_sample orig_sample;
>
> + perf_sample__init(&orig_sample, /*all=*/false);
> ret = evlist__parse_sample(evlist, de->event, &orig_sample);
> if (ret < 0) {
> pr_err("failed to parse original sample\n");
> + perf_sample__exit(&orig_sample);
> break;
> }
>
> - if (sample->tid != orig_sample.tid)
> + if (sample->tid != orig_sample.tid) {
> + perf_sample__exit(&orig_sample);
> continue;
> + }
>
> if (event->callchain_deferred.cookie == orig_sample.deferred_cookie)
> sample__merge_deferred_callchain(&orig_sample, sample);
> @@ -1385,9 +1389,7 @@ static int evlist__deliver_deferred_callchain(struct evlist *evlist,
> ret = evlist__deliver_sample(evlist, tool, de->event,
> &orig_sample, evsel, machine);
>
> - if (orig_sample.deferred_callchain)
> - free(orig_sample.callchain);
> -
> + perf_sample__exit(&orig_sample);
> list_del(&de->list);
> free(de->event);
> free(de);
> @@ -1414,9 +1416,11 @@ static int session__flush_deferred_samples(struct perf_session *session,
> list_for_each_entry_safe(de, tmp, &evlist->deferred_samples, list) {
> struct perf_sample sample;
>
> + perf_sample__init(&sample, /*all=*/false);
> ret = evlist__parse_sample(evlist, de->event, &sample);
> if (ret < 0) {
> pr_err("failed to parse original sample\n");
> + perf_sample__exit(&sample);
> break;
> }
>
> @@ -1424,6 +1428,7 @@ static int session__flush_deferred_samples(struct perf_session *session,
> ret = evlist__deliver_sample(evlist, tool, de->event,
> &sample, evsel, machine);
>
> + perf_sample__exit(&sample);
> list_del(&de->list);
> free(de->event);
> free(de);
> --
> 2.53.0.239.g8d8fc8a987-goog
>