Re: [PATCH v5 17/40] x86/resctrl: Rewrite and move the for_each_*_rdt_resource() walkers

[Reinette Chatre]

Hi James,

On 10/4/24 11:03 AM, James Morse wrote:
> The for_each_*_rdt_resource() helpers walk the architecture's array
> of structures, using the resctrl visible part as an iterator. These
> became over-complex when the structures were split into a
> filesystem and architecture-specific struct. This approach avoided
> the need to touch every call site, and was done before there was a
> helper to retrieve a resource by rid.
> 
> Once the filesystem parts of resctrl are moved to /fs/, both the
> architecture's resource array, and the definition of those structures
> is no longer accessible. To support resctrl, each architecture would
> have to provide equally complex macros.
> 
> Rewrite the macro to make use of resctrl_arch_get_resource(), and
> move these to the core header so existing x86 arch code continues
> to use them.

The last part is not clear, why does it need to be moved to core
header for x86 to use it?


...

> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 8894aed3c593..f75f0409ae09 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -26,6 +26,24 @@ int proc_resctrl_show(struct seq_file *m,
>  /* max value for struct rdt_domain's mbps_val */
>  #define MBA_MAX_MBPS   U32_MAX
>  
> +/* Walk all possible resources, with variants for only controls or monitors. */
> +#define for_each_rdt_resource(_r)						\
> +	for ((_r) = resctrl_arch_get_resource(0);				\
> +	     (_r)->rid < RDT_NUM_RESOURCES - 1;					\

I do not think this reaches all resources ... should this perhaps be:
	(_r) && (_r)->rid < RDT_NUM_RESOURCES

> +	     (_r) = resctrl_arch_get_resource((_r)->rid + 1))
> +
> +#define for_each_capable_rdt_resource(r)				      \
> +	for_each_rdt_resource((r))					      \
> +		if ((r)->alloc_capable || (r)->mon_capable)
> +
> +#define for_each_alloc_capable_rdt_resource(r)				      \
> +	for_each_rdt_resource((r))					      \
> +		if ((r)->alloc_capable)
> +
> +#define for_each_mon_capable_rdt_resource(r)				      \
> +	for_each_rdt_resource((r))					      \
> +		if ((r)->mon_capable)
> +
>  /**
>   * enum resctrl_conf_type - The type of configuration.
>   * @CDP_NONE:	No prioritisation, both code and data are controlled or monitored.

Reinette