Re: [PATCH 3/8] perf sched: Include file offset in event skip messages

[Ian Rogers]

On Tue, Jun 2, 2026 at 4:57 PM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
>
> Add the perf.data file offset to the CPU out-of-bounds and
> machine__resolve failure messages emitted when samples are skipped in
> process_sched_switch_event(), process_sched_runtime_event(), and
> timehist_sched_change_event().  Also switch event type from raw integer
> to perf_event__name() string for readability.
>
> Assisted-by: Claude Opus 4.6 <noreply@xxxxxxxxxxxxx>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/builtin-sched.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index 812a1b0d56d6e5f3..9ec8e049e19b0038 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -1792,8 +1792,10 @@ static int process_sched_switch_event(const struct perf_tool *tool,
>         u32 prev_pid = perf_sample__intval(sample, "prev_pid"),
>             next_pid = perf_sample__intval(sample, "next_pid");
>
> +       /* perf.data is untrusted input — CPU may be absent or corrupted */
>         if (this_cpu < 0 || this_cpu >= MAX_CPUS) {
> -               pr_warning("Out-of-bound sample CPU %d. Skipping sample\n", this_cpu);
> +               pr_warning("WARNING: at offset %#" PRIx64 ": out-of-bound sample CPU %d, skipping sample\n",
> +                          sample->file_offset, this_cpu);
>                 return 0;
>         }
>
> @@ -1819,8 +1821,10 @@ static int process_sched_runtime_event(const struct perf_tool *tool,
>  {
>         struct perf_sched *sched = container_of(tool, struct perf_sched, tool);
>
> +       /* perf.data is untrusted input — CPU may be absent or corrupted */
>         if (sample->cpu >= MAX_CPUS) {
> -               pr_warning("Out-of-bound sample CPU %u. Skipping sample\n", sample->cpu);
> +               pr_warning("WARNING: at offset %#" PRIx64 ": out-of-bound sample CPU %u, skipping sample\n",
> +                          sample->file_offset, sample->cpu);
>                 return 0;
>         }
>
> @@ -2786,15 +2790,18 @@ static int timehist_sched_change_event(const struct perf_tool *tool,
>         int rc = 0;
>         const char state = perf_sample__taskstate(sample, "prev_state");
>
> +       /* perf.data is untrusted input — CPU may be absent or corrupted */
>         if (sample->cpu >= MAX_CPUS) {
> -               pr_warning("Out-of-bound sample CPU %d. Skipping sample\n", sample->cpu);
> +               pr_warning("WARNING: at offset %#" PRIx64 ": out-of-bound sample CPU %d, skipping sample\n",
> +                          sample->file_offset, sample->cpu);
>                 return 0;
>         }
>
>         addr_location__init(&al);
>         if (machine__resolve(machine, &al, sample) < 0) {
> -               pr_err("problem processing %d event. skipping it\n",
> -                      event->header.type);
> +               pr_err("problem processing %s (%u) event at offset %#" PRIx64 ", skipping it\n",
> +                      perf_event__name(event->header.type), event->header.type,
> +                      sample->file_offset);
>                 rc = -1;
>                 goto out;
>         }
> --
> 2.54.0
>