[PATCH RFC] RDMA/core: Handle ARPHRD_NONE devices

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

We would like to enable the use of siw on top of a VPN that is
constructed and managed via a tun device. That hasn't worked up
until now because ARPHRD_NONE devices (such as tun devices) have
no GID for the RDMA/core to look up.

But it turns out that the egress device has already been picked for
us. addr_handler() just has to do the right thing with it.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 drivers/infiniband/core/cma.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 56e568fcd32b..3351dc5afa17 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -704,11 +704,15 @@ cma_validate_port(struct ib_device *device, u32 port,
 		ndev = dev_get_by_index(dev_addr->net, bound_if_index);
 		if (!ndev)
 			return ERR_PTR(-ENODEV);
+	} else if (dev_type == ARPHRD_NONE) {
+		sgid_attr = rdma_get_gid_attr(device, port, 0);
+		goto out;
 	} else {
 		gid_type = IB_GID_TYPE_IB;
 	}
 
 	sgid_attr = rdma_find_gid_by_port(device, gid, gid_type, port, ndev);
+out:
 	dev_put(ndev);
 	return sgid_attr;
 }