Commit 6c1785cd authored by Ian Rogers's avatar Ian Rogers Committed by Namhyung Kim
Browse files

perf record: Ensure space for lost samples 



Previous allocation didn't account for sample ID written after the
lost samples event. Switch from malloc/free to a stack allocation.

Reported-by: default avatarMilian Wolff <milian.wolff@kdab.com>
Closes: https://lore.kernel.org/linux-perf-users/23879991.0LEYPuXRzz@milian-workstation/


Signed-off-by: default avatarIan Rogers <irogers@google.com>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240611050626.1223155-1-irogers@google.com
parent 6828d692

tools/lib/perf/include/perf/event.h

+6 −0
Original line number Diff line number Diff line
@@ -77,6 +77,12 @@ struct perf_record_lost_samples { 
	__u64			 lost;

};



#define MAX_ID_HDR_ENTRIES  6

struct perf_record_lost_samples_and_ids {

	struct perf_record_lost_samples lost;

	__u64 sample_ids[MAX_ID_HDR_ENTRIES];

};



/*

 * PERF_FORMAT_ENABLED | PERF_FORMAT_RUNNING | PERF_FORMAT_ID | PERF_FORMAT_LOST

 */

tools/perf/builtin-record.c

+9 −25
Original line number Diff line number Diff line
@@ -1926,7 +1926,7 @@ static void __record__save_lost_samples(struct record *rec, struct evsel *evsel, 
static void record__read_lost_samples(struct record *rec)

{

	struct perf_session *session = rec->session;

	struct perf_record_lost_samples *lost = NULL;

	struct perf_record_lost_samples_and_ids lost;

	struct evsel *evsel;



	/* there was an error during record__open */
@@ -1951,20 +1951,13 @@ static void record__read_lost_samples(struct record *rec) 


				if (perf_evsel__read(&evsel->core, x, y, &count) < 0) {

					pr_debug("read LOST count failed\n");

					goto out;

					return;

				}



				if (count.lost) {

					if (!lost) {

						lost = zalloc(sizeof(*lost) +

							      session->machines.host.id_hdr_size);

						if (!lost) {

							pr_debug("Memory allocation failed\n");

							return;

						}

						lost->header.type = PERF_RECORD_LOST_SAMPLES;

					}

					__record__save_lost_samples(rec, evsel, lost,

					memset(&lost.lost, 0, sizeof(lost));

					lost.lost.header.type = PERF_RECORD_LOST_SAMPLES;

					__record__save_lost_samples(rec, evsel, &lost.lost,

								    x, y, count.lost, 0);

				}

			}
@@ -1972,21 +1965,12 @@ static void record__read_lost_samples(struct record *rec) 


		lost_count = perf_bpf_filter__lost_count(evsel);

		if (lost_count) {

			if (!lost) {

				lost = zalloc(sizeof(*lost) +

					      session->machines.host.id_hdr_size);

				if (!lost) {

					pr_debug("Memory allocation failed\n");

					return;

				}

				lost->header.type = PERF_RECORD_LOST_SAMPLES;

			}

			__record__save_lost_samples(rec, evsel, lost, 0, 0, lost_count,

			memset(&lost.lost, 0, sizeof(lost));

			lost.lost.header.type = PERF_RECORD_LOST_SAMPLES;

			__record__save_lost_samples(rec, evsel, &lost.lost, 0, 0, lost_count,

						    PERF_RECORD_MISC_LOST_SAMPLES_BPF);

		}

	}

out:

	free(lost);

}



static volatile sig_atomic_t workload_exec_errno;