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

[Namhyung Kim <namhyung@kernel.org>]

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`.

Thanks,
Namhyung

> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  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
>