Re: [PATCH v5 02/40] x86/resctrl: Add a helper to avoid reaching into the arch code resource list

[Tony Luck]

On Fri, Oct 04, 2024 at 06:03:09PM +0000, James Morse wrote:
> +struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l)
> +{
> +	if (l >= RDT_NUM_RESOURCES)
> +		return NULL;
> +
> +	return &rdt_resources_all[l].r_resctrl;
> +}

Is this a bit fragile if someone adds a new item in enum resctrl_res_level
but doesn't add a new entry to struct rdt_hw_resource rdt_resources_all[]
in arch/x86/kernel/cpu/resctrl/core.c

Any caller of resctrl_arch_get_resource(new item name) will get past
the check "if (l >= RDT_NUM_RESOURCES)" and then return a pointer past
the end of the rdt_resources_all[] array.

Maybe make sure the array is padded out to the right size?

struct rdt_hw_resource rdt_resources_all[RDT_NUM_RESOURCES - 1] = {
	...
};

-Tony