Re: [PATCH V8 01/12] perf/core: Add aux_pause, aux_resume, aux_start_paused

[Peter Zijlstra <peterz@infradead.org>]

On Fri, Jun 28, 2024 at 09:51:00AM +0300, Adrian Hunter wrote:

> +	union {
> +		__u32	aux_action;
> +		struct {
> +			__u32	aux_start_paused :  1, /* start AUX area tracing paused */
> +				aux_pause        :  1, /* on overflow, pause AUX area tracing */
> +				aux_resume       :  1, /* on overflow, resume AUX area tracing */
> +				__reserved_3     : 29;
> +		};
> +	};

> @@ -12860,7 +12930,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
>  	 * Grouping is not supported for kernel events, neither is 'AUX',
>  	 * make sure the caller's intentions are adjusted.
>  	 */
> -	if (attr->aux_output)
> +	if (attr->aux_output || attr->aux_action)
>  		return ERR_PTR(-EINVAL);
>  

AFAICT this is the only usage of aux_action. But in a few patches time
you'll introduce a helper along the lines of has_aux_action() that tests
all the individual bits.

Combined with perf_copy_attr() ensuring __reserved_3 is actually 0, I'm
thinking that should all be enough to render this aux_action field
surplus to requirement, and we can simplify all this somewhat, no?