On Fri, Jul 17, 2026 at 06:45:17AM +0000, Jack Ma wrote:
> When an fdb entry points at a nexthop group, vxlan_fdb_nh_path_select()
> resolves the selected leg's remote IP but leaves the UDP destination port
> at the device default (vxlan->cfg.dst_port).
>
> Extend nexthop_path_fdb_result() to also return the selected nexthop's
> NHA_FDB_PORT (0 when unset) and have vxlan_fdb_nh_path_select() store it
> in rdst->remote_port. vxlan_xmit_one() already prefers rdst->remote_port
> when non-zero and falls back to the device port otherwise, so nexthops
> without a port are unaffected.
>
> This lets one fdb nexthop group load-balance a flow across legs that
> share an underlay IP but differ in UDP destination port.
>
> Signed-off-by: Jack Ma <[email protected]>
> ---
> include/net/nexthop.h | 5 ++++-
> include/net/vxlan.h | 5 ++++-
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/nexthop.h b/include/net/nexthop.h
> index 9c8227996..7fb612a73 100644
> --- a/include/net/nexthop.h
> +++ b/include/net/nexthop.h
> @@ -576,7 +576,8 @@ struct fib_nh_common *nexthop_fdb_nhc(struct nexthop *nh)
> }
>
> static inline struct fib_nh_common *nexthop_path_fdb_result(struct nexthop
> *nh,
> - int hash)
> + int hash,
> + __be16 *fdb_port)
Alignment is off
> {
> struct nh_info *nhi;
> struct nexthop *nhp;
> @@ -585,6 +586,8 @@ static inline struct fib_nh_common
> *nexthop_path_fdb_result(struct nexthop *nh,
> if (unlikely(!nhp))
> return NULL;
> nhi = rcu_dereference(nhp->nh_info);
> + if (fdb_port)
Remove the check given 'fdb_port' is never NULL?
> + *fdb_port = nhi->fdb_port;
> return &nhi->fib_nhc;
> }
> #endif
> diff --git a/include/net/vxlan.h b/include/net/vxlan.h
> index dfba89695..de41b3746 100644
> --- a/include/net/vxlan.h
> +++ b/include/net/vxlan.h
> @@ -567,8 +567,9 @@ static inline bool vxlan_fdb_nh_path_select(struct
> nexthop *nh,
> struct vxlan_rdst *rdst)
> {
> struct fib_nh_common *nhc;
> + __be16 fdb_port = 0;
>
> - nhc = nexthop_path_fdb_result(nh, hash >> 1);
> + nhc = nexthop_path_fdb_result(nh, hash >> 1, &fdb_port);
> if (unlikely(!nhc))
> return false;
>
> @@ -583,6 +584,8 @@ static inline bool vxlan_fdb_nh_path_select(struct
> nexthop *nh,
> break;
> }
>
> + rdst->remote_port = fdb_port;
> +
> return true;
> }
>
>
> --
> 2.43.0
>
