Merge branch 'xsk-support-redirect-to-any-socket-bound-to-the-same-umem'

Merge branch 'xsk-support-redirect-to-any-socket-bound-to-the-same-umem'

Magnus Karlsson says:

====================
xsk: support redirect to any socket bound to the same umem

This patch set adds support for directing a packet to any socket bound
to the same umem. This makes it possible to use the XDP program to
select what socket the packet should be received on. The user can
populate the XSKMAP with various sockets and as long as they share the
same umem, the XDP program can pick any one of them.

The implementation is straight-forward. Instead of testing that the
incoming packet is targeting the same device and queue id as the
socket is bound to, just check that the umem the packet was received
on is the same as the socket we want it to be received on. This
guarantees that the redirect is legal as it is already in the correct
umem.

Patch #1 implements the feature and patch #2 adds documentation.

Thanks: Magnus
====================

Link: https://lore.kernel.org/r/20240205123553.22180-1-magnus.karlsson@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>