Re: [PATCH 1/2] mm/vmalloc: Add interfaces to free unused page table

[Kani, Toshi]

On Wed, 2018-03-07 at 20:00 -0800, Matthew Wilcox wrote:
> On Wed, Mar 07, 2018 at 11:32:26AM -0700, Toshi Kani wrote:
> > +/**
> > + * pud_free_pmd_page - clear pud entry and free pmd page
> > + *
> > + * Returns 1 on success and 0 on failure (pud not cleared).
> > + */
> > +int pud_free_pmd_page(pud_t *pud)
> > +{
> > +	return pud_none(*pud);
> > +}
> 
> Wouldn't it be clearer if you returned 'bool' instead of 'int' here?

I thought about it and decided to use 'int' since all other pud/pmd/pte
interfaces, such as pud_none() above, use 'int'.

> Also you didn't document the pud parameter, nor use the approved form
> for documenting the return type, nor the calling context.  So I would
> have written it out like this:
> 
> /**
>  * pud_free_pmd_page - Clear pud entry and free pmd page.
>  * @pud: Pointer to a PUD.
>  *
>  * Context: Caller should hold mmap_sem write-locked.
>  * Return: %true if clearing the entry succeeded.
>  */

Will do.

Thanks!
-Toshi