Re: [Xen-devel] [PATCH 4/4] x86/mm: More discriptive names for page de/validation functions

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.12.2019 13:00, George Dunlap wrote:
> 
> 
>> On Dec 13, 2019, at 10:48 AM, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>>
>> On 12.12.2019 21:07, Andrew Cooper wrote:
>>> On 12/12/2019 17:32, George Dunlap wrote:
>>>> The functions alloc_page_type(), alloc_lN_table(), free_page_type()
>>>> and free_lN_table() are confusingly named:
>>>
>>> There is alloc_segdesc_page() which should be adjusted for consistency.
>>>
>>>> nothing is being allocated or freed.
>>>
>>> Well - strictly speaking the type reference is being obtained/dropped,
>>> and this is a kind of alloc/free, although I agree that the names are
>>> not great.
> 
> On the contrary — the type reference was obtained / will be dropped in 
> {get,put}_page_type(); but the page has not yet been validated to actually be 
> used as that type / still holds references to other pages as though it were 
> that type.  
> 
>>>
>>> However, I'm not entirely sure that {de,}validate are great either,
>>> because it isn't obviously tied to obtaining/dropping a type reference.
>>>
>>> That said, I don't have a better suggestion right now.
>>
>> Following the wording of yours, how about {obtain,drop}_page_type()?
> 
> “Obtain” is literally a synonym for “get”; and there are many places in the 
> code where we say thing like, “drop the type count” just before calling 
> “put”.  
> 
> I agree “devalidate” looks a bit clunky, but all through the discussions on 
> XSA-299, the word “de-validate” was used for the work that the “free" 
> functions are doing — namely, dropping references to other pages such that 
> the “validate” bit is clear.

True.

> I mean, we could do something like “bless” and “unbless”, but I hardly think 
> that’s more clear.  “promote” and “demote”?

Why not. Perhaps with the trailing _type also dropped?

Jan

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