Re: [PATCH v1 1/2] perf sched: Avoid segv if tp_handler not set

[Ian Rogers]

On Thu, Mar 26, 2026 at 4:20 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> On Fri, Mar 20, 2026 at 11:14:47PM -0700, Ian Rogers wrote:
> > Doing a `perf sched record` then `perf sched stats report` crashes as
> > the tp_handler isn't set. Add extra checks that tp_handler is set
> > before accessing through it.
>
> Oh.. unintended use case. :)  Probably better to add a dummy handler
> for `perf sched stats report`.

Perhaps. I'd prefer to land the simpler change as-is.

Thanks,
Ian

> Thanks,
> Namhyung
>
> >
> > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > ---
> >  tools/perf/builtin-sched.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> > index d083e2bb7703..196f263ff667 100644
> > --- a/tools/perf/builtin-sched.c
> > +++ b/tools/perf/builtin-sched.c
> > @@ -1525,7 +1525,7 @@ static int process_sched_wakeup_event(const struct perf_tool *tool,
> >  {
> >       struct perf_sched *sched = container_of(tool, struct perf_sched, tool);
> >
> > -     if (sched->tp_handler->wakeup_event)
> > +     if (sched->tp_handler && sched->tp_handler->wakeup_event)
> >               return sched->tp_handler->wakeup_event(sched, evsel, sample, machine);
> >
> >       return 0;
> > @@ -1809,7 +1809,7 @@ static int process_sched_switch_event(const struct perf_tool *tool,
> >                       sched->nr_context_switch_bugs++;
> >       }
> >
> > -     if (sched->tp_handler->switch_event)
> > +     if (sched->tp_handler && sched->tp_handler->switch_event)
> >               err = sched->tp_handler->switch_event(sched, evsel, sample, machine);
> >
> >       sched->curr_pid[this_cpu] = next_pid;
> > @@ -1823,7 +1823,7 @@ static int process_sched_runtime_event(const struct perf_tool *tool,
> >  {
> >       struct perf_sched *sched = container_of(tool, struct perf_sched, tool);
> >
> > -     if (sched->tp_handler->runtime_event)
> > +     if (sched->tp_handler && sched->tp_handler->runtime_event)
> >               return sched->tp_handler->runtime_event(sched, evsel, sample, machine);
> >
> >       return 0;
> > @@ -1840,7 +1840,7 @@ static int perf_sched__process_fork_event(const struct perf_tool *tool,
> >       perf_event__process_fork(tool, event, sample, machine);
> >
> >       /* and then run additional processing needed for this command */
> > -     if (sched->tp_handler->fork_event)
> > +     if (sched->tp_handler && sched->tp_handler->fork_event)
> >               return sched->tp_handler->fork_event(sched, event, machine);
> >
> >       return 0;
> > @@ -1853,7 +1853,7 @@ static int process_sched_migrate_task_event(const struct perf_tool *tool,
> >  {
> >       struct perf_sched *sched = container_of(tool, struct perf_sched, tool);
> >
> > -     if (sched->tp_handler->migrate_task_event)
> > +     if (sched->tp_handler && sched->tp_handler->migrate_task_event)
> >               return sched->tp_handler->migrate_task_event(sched, evsel, sample, machine);
> >
> >       return 0;
> > --
> > 2.53.0.959.g497ff81fa9-goog
> >