On 2/2/26 22:37, Gregory Price wrote:

On Mon, Feb 02, 2026 at 06:46:09PM +0000, Jonathan Cameron wrote:

quoted

quoted

I can add a cleanup-patch prior to use the enum, but i don't think this
actually enables the compiler to do anything new at the moment?

Good point. More coffee needed (or sleep)

It lets sparse do some checking, but sadly only for wrong enum assignment.
(Gcc has -Wenum-conversion as well which I think is effectively the same)
I.e. you can't assign a value from a different enum without casting.

It can't do anything if people just pass in an out of range int.

Which, after looking a bit... mm/memory_hotplug.c does this quite a bit
internally - except it uses a uint8_t

Example:

static int try_offline_memory_block(struct memory_block *mem, void *arg)
{
         uint8_t online_type = MMOP_ONLINE_KERNEL;
         uint8_t **online_types = arg;
	... snip ...
}

int offline_and_remove_memory(u64 start, u64 size)
{
         uint8_t *online_types, *tmp;
	... snip ...
         online_types = kmalloc_array(mb_count, sizeof(*online_types),
                                      GFP_KERNEL);
}

So that's fun.

I'm not sure it's worth the churn here, but happy to do it if there are
strong opinions.

---

David do you have thoughts here?

I guess we should clean that all up where easily possible, but I don't 
expect you to do that.

For online_types I used it, obviously, to save memory. So I'd expect it 
to stay at least there, but cast it to the proper type once we take it 
out the array.

-- 
Cheers,

David