[PATCH for-next v3] RDMA/rxe: fix regression caused by recent patch

[Bob Pearson <rpearsonhpe@gmail.com>]

The commit referenced below performs additional checking on
devices used for DMA. Specifically it checks that

device->dma_mask != NULL

Rdma_rxe uses this device when pinning MR memory but did not
set the value of dma_mask. In fact rdma_rxe does not perform
any DMA operations so the value is never used but is checked.

This patch gives dma_mask a valid value.  It also removes unnecessary
logic which was setting dev->parent. It is equivalent to the patch
submitted by Parav Pandit.

Fixes: f959dcd6ddfd2 ("dma-direct: Fix potential NULL pointer dereference")
Signed-off-by: Bob Pearson <rpearson@hpe.com>
---
 drivers/infiniband/sw/rxe/rxe_loc.h   |  1 -
 drivers/infiniband/sw/rxe/rxe_net.c   | 12 ------------
 drivers/infiniband/sw/rxe/rxe_verbs.c | 10 ++++++++--
 3 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
index 0d758760b9ae..8adcef54e4b3 100644
--- a/drivers/infiniband/sw/rxe/rxe_loc.h
+++ b/drivers/infiniband/sw/rxe/rxe_loc.h
@@ -116,7 +116,6 @@ struct sk_buff *rxe_init_packet(struct rxe_dev *rxe, struct rxe_av *av,
 				int paylen, struct rxe_pkt_info *pkt);
 int rxe_prepare(struct rxe_pkt_info *pkt, struct sk_buff *skb, u32 *crc);
 const char *rxe_parent_name(struct rxe_dev *rxe, unsigned int port_num);
-struct device *rxe_dma_device(struct rxe_dev *rxe);
 int rxe_mcast_add(struct rxe_dev *rxe, union ib_gid *mgid);
 int rxe_mcast_delete(struct rxe_dev *rxe, union ib_gid *mgid);
 
diff --git a/drivers/infiniband/sw/rxe/rxe_net.c b/drivers/infiniband/sw/rxe/rxe_net.c
index 575e1a4ec821..2b4238cdeab9 100644
--- a/drivers/infiniband/sw/rxe/rxe_net.c
+++ b/drivers/infiniband/sw/rxe/rxe_net.c
@@ -20,18 +20,6 @@
 
 static struct rxe_recv_sockets recv_sockets;
 
-struct device *rxe_dma_device(struct rxe_dev *rxe)
-{
-	struct net_device *ndev;
-
-	ndev = rxe->ndev;
-
-	if (is_vlan_dev(ndev))
-		ndev = vlan_dev_real_dev(ndev);
-
-	return ndev->dev.parent;
-}
-
 int rxe_mcast_add(struct rxe_dev *rxe, union ib_gid *mgid)
 {
 	int err;
diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
index 7652d53af2c1..6afbb507ddb1 100644
--- a/drivers/infiniband/sw/rxe/rxe_verbs.c
+++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
@@ -1128,19 +1128,25 @@ int rxe_register_device(struct rxe_dev *rxe, const char *ibdev_name)
 	int err;
 	struct ib_device *dev = &rxe->ib_dev;
 	struct crypto_shash *tfm;
+	u64 dma_mask;
 
 	strlcpy(dev->node_desc, "rxe", sizeof(dev->node_desc));
 
 	dev->node_type = RDMA_NODE_IB_CA;
 	dev->phys_port_cnt = 1;
 	dev->num_comp_vectors = num_possible_cpus();
-	dev->dev.parent = rxe_dma_device(rxe);
 	dev->local_dma_lkey = 0;
 	addrconf_addr_eui48((unsigned char *)&dev->node_guid,
 			    rxe->ndev->dev_addr);
 	dev->dev.dma_parms = &rxe->dma_parms;
 	dma_set_max_seg_size(&dev->dev, UINT_MAX);
-	dma_set_coherent_mask(&dev->dev, dma_get_required_mask(&dev->dev));
+	dma_mask = IS_ENABLED(CONFIG_64BIT) ? DMA_BIT_MASK(64)
+					    : DMA_BIT_MASK(32);
+	err = dma_coerce_mask_and_coherent(&dev->dev, dma_mask);
+	if (err) {
+		pr_warn("unable to set dma_mask, err = %d\n", err);
+		return err;
+	}
 
 	dev->uverbs_cmd_mask |= BIT_ULL(IB_USER_VERBS_CMD_REQ_NOTIFY_CQ);
 
-- 
2.27.0