[PATCH v2] RDMA/cma: Handle ARPHRD_NONE devices for iWARP

[Chuck Lever <cel@xxxxxxxxxx>]

From: Chuck Lever <chuck.lever@xxxxxxxxxx>

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 -- no GID is necessary. addr_handler() just has to do the right
thing with it.

Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 drivers/infiniband/core/cma.c |   27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

Further testing convinced me of the necessity of confirming that
the ndev and ib_device are properly related. This version works
on systems with multiple RDMA devices present.


diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 56e568fcd32b..44ef0539957a 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -686,30 +686,47 @@ cma_validate_port(struct ib_device *device, u32 port,
 		  struct rdma_id_private *id_priv)
 {
 	struct rdma_dev_addr *dev_addr = &id_priv->id.route.addr.dev_addr;
+	const struct ib_gid_attr *sgid_attr = ERR_PTR(-ENODEV);
 	int bound_if_index = dev_addr->bound_dev_if;
-	const struct ib_gid_attr *sgid_attr;
 	int dev_type = dev_addr->dev_type;
 	struct net_device *ndev = NULL;
 
 	if (!rdma_dev_access_netns(device, id_priv->id.route.addr.dev_addr.net))
-		return ERR_PTR(-ENODEV);
+		goto out;
+
+	if (rdma_protocol_iwarp(device, port)) {
+		struct ib_device *base_dev;
+
+		ndev = dev_get_by_index(dev_addr->net, bound_if_index);
+		if (!ndev)
+			goto out;
+		base_dev = ib_device_get_by_netdev(ndev, RDMA_DRIVER_UNKNOWN);
+		if (base_dev)
+			ib_device_put(base_dev);
+		dev_put(ndev);
+
+		if (device == base_dev)
+			sgid_attr = rdma_get_gid_attr(device, port, 0);
+		goto out;
+	}
 
 	if ((dev_type == ARPHRD_INFINIBAND) && !rdma_protocol_ib(device, port))
-		return ERR_PTR(-ENODEV);
+		goto out;
 
 	if ((dev_type != ARPHRD_INFINIBAND) && rdma_protocol_ib(device, port))
-		return ERR_PTR(-ENODEV);
+		goto out;
 
 	if (dev_type == ARPHRD_ETHER && rdma_protocol_roce(device, port)) {
 		ndev = dev_get_by_index(dev_addr->net, bound_if_index);
 		if (!ndev)
-			return ERR_PTR(-ENODEV);
+			goto out;
 	} else {
 		gid_type = IB_GID_TYPE_IB;
 	}
 
 	sgid_attr = rdma_find_gid_by_port(device, gid, gid_type, port, ndev);
 	dev_put(ndev);
+out:
 	return sgid_attr;
 }