Re: [PATCH v4 2/6] perf: Enqueue SIGTRAP always via task_work.

[Peter Zijlstra]

On Mon, Jun 24, 2024 at 05:15:15PM +0200, Sebastian Andrzej Siewior wrote:
> @@ -9735,18 +9719,28 @@ static int __perf_event_overflow(struct perf_event *event,
>  
>  		if (regs)
>  			pending_id = hash32_ptr((void *)instruction_pointer(regs)) ?: 1;
> -		if (!event->pending_sigtrap) {
> -			event->pending_sigtrap = pending_id;
> +
> +		if (!event->pending_work &&
> +		    !task_work_add(current, &event->pending_task, TWA_RESUME)) {
> +			event->pending_work = pending_id;
>  			local_inc(&event->ctx->nr_pending);

task_work_add() isn't NMI safe, at the very least the
kasan_record_aux_stack() thing needs to go. But the whole
set_notify_resume() thing also needs an audit.