linux-kernel - Re: [PATCH net-next v5 2/3] net: mirror skb frag ref/unref helpers

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Date: Tue, 9 Apr 2024 18:23:01 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Mina Almasry <almasrymina@...gle.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, Ayush Sawal
 <ayush.sawal@...lsio.com>, "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Jesper
 Dangaard Brouer <hawk@...nel.org>, Ilias Apalodimas
 <ilias.apalodimas@...aro.org>, Steffen Klassert
 <steffen.klassert@...unet.com>, Herbert Xu <herbert@...dor.apana.org.au>,
 David Ahern <dsahern@...nel.org>, Boris Pismenny <borisp@...dia.com>, John
 Fastabend <john.fastabend@...il.com>, Dragos Tatulea <dtatulea@...dia.com>
Subject: Re: [PATCH net-next v5 2/3] net: mirror skb frag ref/unref helpers

On Mon,  8 Apr 2024 08:29:57 -0700 Mina Almasry wrote:
> +#ifdef CONFIG_PAGE_POOL
> +static inline bool is_pp_page(struct page *page)
> +{
> +	return (page->pp_magic & ~0x3UL) == PP_SIGNATURE;
> +}
> +
> +/* page_pool_unref_page() lives in net/page_pool/helpers.h */
> +static inline void page_pool_ref_page(struct page *page)
> +{
> +	atomic_long_inc(&page->pp_ref_count);
> +}
> +
> +static inline bool napi_pp_get_page(struct page *page)
> +{
> +	page = compound_head(page);
> +
> +	if (!is_pp_page(page))
> +		return false;
> +
> +	page_pool_ref_page(page);
> +	return true;
> +}
> +#endif
> +
> +static inline void skb_page_ref(struct page *page, bool recycle)
> +{
> +#ifdef CONFIG_PAGE_POOL
> +	if (recycle && napi_pp_get_page(page))
> +		return;
> +#endif
> +	get_page(page);
> +}

Shifting of all this code from pp to skbuff catches the eye.
There aren't that many callers to these, can we start a new header?
We can then include page pool headers in the without worry.

I'll apply the other patches, they look independent.