[RFC,0/3] siw on tunnel devices

Message

Chuck Lever May 5, 2023, 3:41 p.m. UTC

Chalk this one up to yet another crazy idea.

At NFS testing events, we'd like to test NFS/RDMA over the event's
private network. We can do that with iWARP using siw from guests.

If the guest itself is on the VPN, that means siw's slave device
is a tun device. Such devices have no MAC address. That breaks the
RDMA core's ability to find the correct egress device for siw when
given a source IP address.

We've worked around this in the past with various software hacks,
but we'd rather see full support for this capability in stock
kernels.

A direct and perhaps naïve way to do that is to give loopback and
tun devices their own artificial MAC addresses for this purpose.

---

Chuck Lever (3):
      net/tun: Ensure tun devices have a MAC address
      net/lo: Ensure lo devices have a MAC address
      RDMA/siw: Require non-zero 6-byte MACs for soft iWARP


 drivers/infiniband/sw/siw/siw_main.c | 22 +++++++---------------
 drivers/net/loopback.c               |  2 ++
 drivers/net/tun.c                    |  6 +++---
 3 files changed, 12 insertions(+), 18 deletions(-)

--
Chuck Lever