[PATCH net-next v2 0/3] Abstract page from net stack

[Mina Almasry]

Changes in v2:
- Reverted changes to the page_pool. The page pool now retains the same
  API, so that we don't have to touch many existing drivers. The devmem
  TCP series will include the changes to the page pool.

- Addressed comments.

This series is a prerequisite to the devmem TCP series. For a full
snapshot of the code which includes these changes, feel free to check:

https://github.com/mina/linux/commits/tcpdevmem-rfcv5/

-----------

Currently these components in the net stack use the struct page
directly:

1. Drivers.
2. Page pool.
3. skb_frag_t.

To add support for new (non struct page) memory types to the net stack, we
must first abstract the current memory type.

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 safe compiler type checking we need to introduce a new type.

struct netmem 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@xxxxxxxxxx/

Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
Cc: Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx>

Mina Almasry (3):
  vsock/virtio: use skb_frag_*() helpers
  net: introduce abstraction for network memory
  net: add netmem_t to skb_frag_t

 include/linux/skbuff.h           | 70 ++++++++++++++++++++++++--------
 include/net/netmem.h             | 35 ++++++++++++++++
 net/core/skbuff.c                | 22 +++++++---
 net/kcm/kcmsock.c                | 10 ++++-
 net/vmw_vsock/virtio_transport.c |  6 +--
 5 files changed, 116 insertions(+), 27 deletions(-)
 create mode 100644 include/net/netmem.h

-- 
2.43.0.472.g3155946c3a-goog