RDMA/cma: Skip device which doesn't support CM

A switchdev RDMA device do not support IB CM. When such device is added to
the RDMA CM's device list, when application invokes rdma_listen(), cma
attempts to listen to such device, however it has IB CM attribute
disabled.

Due to this, rdma_listen() call fails to listen for other non switchdev
devices as well.

A below error message can be seen.

infiniband mlx5_0: RDMA CMA: cma_listen_on_dev, error -38

A failing call flow is below.

  cma_listen_on_all()
    cma_listen_on_dev()
      _cma_attach_to_dev()
        rdma_listen() <- fails on a specific switchdev device

This is because rdma_listen() is hardwired to only work with iwarp or IB
CM compatible devices.

Hence, when a IB device doesn't support IB CM or IW CM, avoid adding such
device to the cma list so rdma_listen() can't even be called.

Link: https://lore.kernel.org/r/f9cac00d52864ea7c61295e43fb64cf4db4fdae6.1618753862.git.leonro@nvidia.comSigned-off-by: NParav Pandit <parav@nvidia.com>
Signed-off-by: NLeon Romanovsky <leonro@nvidia.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/cma.c

@@ -4900,6 +4900,17 @@ static void cma_process_remove(struct cma_device *cma_dev)
 	wait_for_completion(&cma_dev->comp);
 }
 
+static bool cma_supported(struct ib_device *device)
+{
+	u32 i;
+
+	rdma_for_each_port(device, i) {
+		if (rdma_cap_ib_cm(device, i) || rdma_cap_iw_cm(device, i))
+			return true;
+	}
+	return false;
+}
+
 static int cma_add_one(struct ib_device *device)
 {
 	struct rdma_id_private *to_destroy;
@@ -4909,6 +4920,9 @@ static int cma_add_one(struct ib_device *device)
 	int ret;
 	u32 i;
 
+	if (!cma_supported(device))
+		return -EOPNOTSUPP;
+
 	cma_dev = kmalloc(sizeof(*cma_dev), GFP_KERNEL);
 	if (!cma_dev)
 		return -ENOMEM;