[PATCH v3] net/af_xdp: fix default device plugin path

[Stephen Hemminger]

On Wed, 12 Aug 2026 01:47:42 +0000
Anurag Mandal <anurag.mandal at intel.com> wrote:

> When use_cni=1 or use_pinned_map=1 is passed without an explicit
> dp_path, the PMD builds the path to the AF_XDP device plugin
> endpoint itself.
> That default was hardcoded to /tmp/afxdp_dp/<if_name>/.
> 
> A unix domain socket and a pinned map are runtime state.
> DPDK exposes a location for such state through
> rte_eal_get_runtime_dir(), which is per user, per
> file prefix, and created with mode 0700, unlike
> the shared /tmp/afxdp_dp directory.
> 
> The location cannot simply be moved as it is a contract
> duplicated in the AF_XDP Device Plugin for Kubernetes,
> which creates the socket and mounts it into the pod at
> the /tmp path the PMD expects.
> Changing only the PMD would break every existing deployment.
> 
> This patch fixes the default so that the endpoint is looked
> up below the EAL runtime directory first, and /tmp/afxdp_dp
> is only used when nothing is found there.
> Use of the fallback is logged at notice level.
> Existing plugin deployments keep working unchanged, while
> a deployment that places the endpoint in the runtime
> directory no longer has to pass dp_path.
> An explicit dp_path still overrides both.
> 
> The <if_name> component is kept in both layouts. It is what
> keeps the endpoints of several interfaces distinct when more
> than one UDS server is mounted in a single pod.
> 
> The runtime directory prefix makes the built path longer,
> so reject a dp_path that does not fit the sun_path field
> of struct sockaddr_un instead of letting strlcpy()
> silently truncate it.
> 
> The interface name check is moved ahead of the path
> construction, as the default path is now built from it.
> 
> Bugzilla ID: 1973
> Fixes: 9c1323736cf9 ("net/af_xdp: fix multi-interface support for k8s")
> Fixes: 8a324b1c6464 ("net/af_xdp: support AF_XDP device plugin pinned maps")
> 
> Signed-off-by: Anurag Mandal <anurag.mandal at intel.com>
> ---

Applied to net-next. I went ahead and cleaned up the release
note and docs. There are still some nits that AI is complaining
about but not really worth spending time resolving.