Re: [PATCH v3 1/5] perf/core: Allow multiple AUX PMU events with the same module

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Aug 06, 2024 at 09:48:09PM +0100, Leo Yan wrote:
> This commit changes the condition from checking the same PMU instance to
> checking the same PMU driver module. This allows support for multiple
> PMU events with the same driver module.
> 
> As a result, more than one AUX event (e.g. arm_spe_0 and arm_spe_1) can
> record trace into the AUX ring buffer.
> 
> Signed-off-by: Leo Yan <leo.yan@arm.com>
> ---
>  kernel/events/core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index aa3450bdc227..fdb8918e62a0 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -12344,9 +12344,10 @@ perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
>  
>  	/*
>  	 * If both events generate aux data, they must be on the same PMU
> +	 * module but can be with different PMU instances.
>  	 */
>  	if (has_aux(event) && has_aux(output_event) &&
> -	    event->pmu != output_event->pmu)
> +	    event->pmu->module != output_event->pmu->module)

A very quick look at: arch/x86/events/intel/pt.c seems to suggest that
doesn't set pmu->module. Which seems to suggest the above won't work for
us.