[v2] net/af_xdp: enable a sock path alongside use_cni

[Stephen Hemminger]

On Mon,  4 Dec 2023 05:31:01 -0500
Maryam Tahhan <mtahhan at redhat.com> wrote:

> With the original 'use_cni' implementation, (using a
> hardcoded socket rather than a configurable one),
> if a single pod is requesting multiple net devices
> and these devices are from different pools, then
> the container attempts to mount all the netdev UDSes
> in the pod as /tmp/afxdp.sock. Which means that at best
> only 1 netdev will handshake correctly with the AF_XDP
> DP. This patch addresses this by making the socket
> parameter configurable alongside the 'use_cni' param.
> Tested with the AF_XDP DP CNI PR 81.
> 
> v2:
> * Rename sock_path to uds_path.
> * Update documentation to reflect when CAP_BPF is needed.
> * Fix testpmd arguments in the provided example for Pods.
> * Use AF_XDP API to update the xskmap entry.
> 
> Signed-off-by: Maryam Tahhan <mtahhan at redhat.com>

Why does XDP PMD not use abstract socket path?
Having actual file visible in file system can cause permission
and leftover file issues that are not present with abstract path.

If you use abstract path then when last reference is gone (ie server exits)
the path is removed. With regular paths, the file gets stuck in the
file system and has to be cleaned up.