RDMA/cma: Don't allow IPoIB port space for IBoE

This patch fixes a kernel crash in cma_set_qkey().

When the link layer is Ethernet, it is wrong to use IPoIB port space
since no IPoIB interface is available.  Specifically, setting the
Q_Key when port space is RDMA_PS_IPOIB requires MGID calculation and
an SA query, which doesn't make sense over Ethernet.
Signed-off-by: Moni Shoua <monis@mellanox.co.il>
Acked-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/core/cma.c

@@ -359,6 +359,10 @@ static int cma_acquire_dev(struct rdma_id_private *id_priv)
 	enum rdma_link_layer dev_ll = dev_addr->dev_type == ARPHRD_INFINIBAND ?
 		IB_LINK_LAYER_INFINIBAND : IB_LINK_LAYER_ETHERNET;
 
+	if (dev_ll != IB_LINK_LAYER_INFINIBAND &&
+	    id_priv->id.ps == RDMA_PS_IPOIB)
+		return -EINVAL;
+
 	mutex_lock(&lock);
 	iboe_addr_get_sgid(dev_addr, &iboe_gid);
 	memcpy(&gid, dev_addr->src_dev_addr +