[PATCH] RDMA/rxe: prevent rxe creation on top of vlan interface

[Mohammad Heib <goody698@gmail.com>]

Creating rxe device on top of vlan interface will create a non-functional device
that has an empty gids table and can't be used for rdma cm communication.

This is caused by the logic in enum_all_gids_of_dev_cb()/is_eth_port_of_netdev(),
which only considers networks connected to "upper devices" of the configured
network device, resulting in an empty set of gids for a vlan interface,
and attempts to connect via this rdma device fail in cm_init_av_for_response
because no gids can be resolved.

apparently, this behavior was implemented to fit the HW-RoCE devices that create
RoCE device per port, therefore RXE must behave the same like HW-RoCE devices
and create rxe device per real device only.

In order to communicate via a vlan interface, the user must use the gid index of
the vlan address instead of creating rxe over vlan.

Signed-off-by: Mohammad Heib <goody698@gmail.com>
---
 drivers/infiniband/sw/rxe/rxe.c       | 6 ++++++
 drivers/infiniband/sw/rxe/rxe_sysfs.c | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/infiniband/sw/rxe/rxe.c b/drivers/infiniband/sw/rxe/rxe.c
index 5642eefb4ba1..d2076aa7a732 100644
--- a/drivers/infiniband/sw/rxe/rxe.c
+++ b/drivers/infiniband/sw/rxe/rxe.c
@@ -310,6 +310,12 @@ static int rxe_newlink(const char *ibdev_name, struct net_device *ndev)
 	struct rxe_dev *exists;
 	int err = 0;
 
+	if (is_vlan_dev(ndev)) {
+		pr_err("rxe creation allowed on top of a real device only\n");
+		err = -EPERM;
+		goto err;
+	}
+
 	exists = rxe_get_dev_from_net(ndev);
 	if (exists) {
 		ib_device_put(&exists->ib_dev);
diff --git a/drivers/infiniband/sw/rxe/rxe_sysfs.c b/drivers/infiniband/sw/rxe/rxe_sysfs.c
index ccda5f5a3bc0..0a083c3d900a 100644
--- a/drivers/infiniband/sw/rxe/rxe_sysfs.c
+++ b/drivers/infiniband/sw/rxe/rxe_sysfs.c
@@ -73,6 +73,12 @@ static int rxe_param_set_add(const char *val, const struct kernel_param *kp)
 		return -EINVAL;
 	}
 
+	if (is_vlan_dev(ndev)) {
+		pr_err("rxe creation allowed on top of a real device only\n");
+		err = -EPERM;
+		goto err;
+	}
+
 	exists = rxe_get_dev_from_net(ndev);
 	if (exists) {
 		ib_device_put(&exists->ib_dev);
-- 
2.26.2