Re: [PATCH v2 26/31] mm: Add __free() support for __free_page()

[Ackerley Tng]

Xu Yilun <yilun.xu@xxxxxxxxxxxxxxx> writes:

> Allow for the declaration of struct page * variables that trigger
> __free_page() when they go out of scope.
>
> A example usage would be in the following patch:
>
>   static struct pci_tsm *tdx_tsm_link_pf0_probe(...)
>   {
> 	...
>
> 	struct page *in_msg_page __free(__free_page) =
> 		alloc_page(GFP_KERNEL | __GFP_ZERO);
> 	if (!in_msg_page)
> 		return NULL;
>
> 	struct page *out_msg_page __free(__free_page) =
> 		alloc_page(GFP_KERNEL | __GFP_ZERO);
> 	if (!out_msg_page)
> 		return NULL;
>
> 	...
>
> 	tlink->in_msg = no_free_ptr(in_msg_page);
> 	tlink->out_msg = no_free_ptr(out_msg_page);
>
> 	...
>   }
>
> Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxxxxxxxx>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
> ---
>  include/linux/gfp.h | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 51ef13ed756e..d37e5564234e 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -391,6 +391,7 @@ extern void free_pages_nolock(struct page *page, unsigned int order);
>  extern void free_pages(unsigned long addr, unsigned int order);
>
>  #define __free_page(page) __free_pages((page), 0)
> +DEFINE_FREE(__free_page, struct page *, if (_T) __free_page(_T))
>  #define free_page(addr) free_pages((addr), 0)
>
>  void page_alloc_init_cpuhp(void);
> --
> 2.25.1

This is nice to have, independent of this series. Perhaps it should be
sent separately, and some existing function could be refactored to use
this, maybe __tdx_td_init?

Reviewed-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>