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perf sched: Suppress latency table output when trace samples are missing

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When 'perf sched latency' is executed on a perf.data file that lacks
tracepoint samples (i.e., a file recorded without the -R flag or
containing only non-tracepoint events), perf_session__has_traces()
correctly outputs an error message. However, perf_sched__read_events()
subsequently falls through and returns 0 (success).

Consequently, caller functions such as perf_sched__lat() assume event
processing succeeded and proceed to render empty latency header tables
and total summary statistics.

Fix this behaviour by ensuring perf_sched__read_events() aborts early and
returns a suitable error code when perf_session__has_traces() evaluates
to false.

Additionally, validate thread__get_runtime() against NULL in
map_switch_event() to prevent potential null-pointer dereferences.

Fixes: 27295592c2 ("perf session: Share the common trace sample_check routine as perf_session__has_traces")
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Aaron Tomlin 2026-08-06 11:39:23 -04:00 committed by Namhyung Kim
parent 006a6f0f6e
commit 4a81d59a9d
1 changed files with 12 additions and 11 deletions
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23
tools/perf/builtin-sched.c
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@ -1833,7 +1833,7 @@ static int map_switch_event(struct perf_sched *sched, struct perf_sample *sampl
sched_out:
if (sched->map.task_name) {
tr = thread__get_runtime(sched->curr_out_thread[this_cpu.cpu]);
if (strcmp(tr->shortname, "") == 0)
if (tr == NULL || strcmp(tr->shortname, "") == 0)
goto out;
if (proceed == 1)
@ -2001,7 +2001,7 @@ static int perf_sched__read_events(struct perf_sched *sched)
.mode = PERF_DATA_MODE_READ,
.force = sched->force,
};
int rc = -1;
int rc = -1, err;
session = perf_session__new(&data, &sched->tool);
if (IS_ERR(session)) {
@ -2018,18 +2018,19 @@ static int perf_sched__read_events(struct perf_sched *sched)
if (perf_session__set_tracepoints_handlers(session, handlers))
goto out_delete;
if (perf_session__has_traces(session, "record -R")) {
int err = perf_session__process_events(session);
if (err) {
pr_err("Failed to process events, error %d", err);
goto out_delete;
}
if (!perf_session__has_traces(session, "record -R"))
goto out_delete;
sched->nr_events = evlist__stats(session->evlist)->nr_events[0];
sched->nr_lost_events = evlist__stats(session->evlist)->total_lost;
sched->nr_lost_chunks = evlist__stats(session->evlist)->nr_events[PERF_RECORD_LOST];
err = perf_session__process_events(session);
if (err) {
pr_err("Failed to process events, error %d", err);
goto out_delete;
}
sched->nr_events = evlist__stats(session->evlist)->nr_events[0];
sched->nr_lost_events = evlist__stats(session->evlist)->total_lost;
sched->nr_lost_chunks = evlist__stats(session->evlist)->nr_events[PERF_RECORD_LOST];
rc = 0;
out_delete:
perf_session__delete(session);