ice: protect ring accesses with WRITE_ONCE

The READ_ONCE macro is used when reading rings prior to accessing the
statistics pointer. The corresponding WRITE_ONCE usage when allocating and
freeing the rings to ensure protected access was not in place. Introduce
this.
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_lib.c

@@ -1194,7 +1194,7 @@ static void ice_vsi_clear_rings(struct ice_vsi *vsi)
 		for (i = 0; i < vsi->alloc_txq; i++) {
 			if (vsi->tx_rings[i]) {
 				kfree_rcu(vsi->tx_rings[i], rcu);
-				vsi->tx_rings[i] = NULL;
+				WRITE_ONCE(vsi->tx_rings[i], NULL);
 			}
 		}
 	}
@@ -1202,7 +1202,7 @@ static void ice_vsi_clear_rings(struct ice_vsi *vsi)
 		for (i = 0; i < vsi->alloc_rxq; i++) {
 			if (vsi->rx_rings[i]) {
 				kfree_rcu(vsi->rx_rings[i], rcu);
-				vsi->rx_rings[i] = NULL;
+				WRITE_ONCE(vsi->rx_rings[i], NULL);
 			}
 		}
 	}
@@ -1235,7 +1235,7 @@ static int ice_vsi_alloc_rings(struct ice_vsi *vsi)
 		ring->vsi = vsi;
 		ring->dev = dev;
 		ring->count = vsi->num_tx_desc;
-		vsi->tx_rings[i] = ring;
+		WRITE_ONCE(vsi->tx_rings[i], ring);
 	}
 
 	/* Allocate Rx rings */
@@ -1254,7 +1254,7 @@ static int ice_vsi_alloc_rings(struct ice_vsi *vsi)
 		ring->netdev = vsi->netdev;
 		ring->dev = dev;
 		ring->count = vsi->num_rx_desc;
-		vsi->rx_rings[i] = ring;
+		WRITE_ONCE(vsi->rx_rings[i], ring);
 	}
 
 	return 0;

drivers/net/ethernet/intel/ice/ice_main.c

@@ -1702,7 +1702,7 @@ static int ice_xdp_alloc_setup_rings(struct ice_vsi *vsi)
 		xdp_ring->netdev = NULL;
 		xdp_ring->dev = dev;
 		xdp_ring->count = vsi->num_tx_desc;
-		vsi->xdp_rings[i] = xdp_ring;
+		WRITE_ONCE(vsi->xdp_rings[i], xdp_ring);
 		if (ice_setup_tx_ring(xdp_ring))
 			goto free_xdp_rings;
 		ice_set_ring_xdp(xdp_ring);