Re: [RFC PATCH net-next v5 1/2] net: introduce abstraction for network memory

[Shakeel Butt <shakeelb@google.com>]

On Mon, Jan 8, 2024 at 5:15 PM Mina Almasry <almasrymina@google.com> wrote:
>
> Add the netmem_ref type, an abstraction for network memory.
>
> To add support for new memory types to the net stack, we must first
> abstract the current memory type. Currently parts of the net stack
> use struct page directly:
>
> - page_pool
> - drivers
> - skb_frag_t
>
> Originally the plan was to reuse struct page* for the new memory types,
> and to set the LSB on the page* to indicate it's not really a page.
> However, for compiler type checking we need to introduce a new type.
>
> netmem_ref is introduced to abstract the underlying memory type.
> Currently it's a no-op abstraction that is always a struct page
> underneath. In parallel there is an undergoing effort to add support
> for devmem to the net stack:
>
> https://lore.kernel.org/netdev/20231208005250.2910004-1-almasrymina@google.com/
>
> netmem_ref can be pointers to different underlying memory types, and the
> low bits are set to indicate the memory type. Helpers are provided
> to convert netmem pointers to the underlying memory type (currently only
> struct page). In the devmem series helpers are provided so that calling
> code can use netmem without worrying about the underlying memory type
> unless absolutely necessary.
>
> Signed-off-by: Mina Almasry <almasrymina@google.com>
>

Reviewed-by: Shakeel Butt <shakeelb@google.com>