veth: factor out initialization helper

Extract in simpler helpers the code to enable and disable a
range of xdp/napi instance, with the common property that
"disable" helpers can't fail.

Will be used by the next patch. No functional change intended.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/veth.c

@@ -926,12 +926,12 @@ static int veth_poll(struct napi_struct *napi, int budget)
 	return done;
 }
 
-static int __veth_napi_enable(struct net_device *dev)
+static int __veth_napi_enable_range(struct net_device *dev, int start, int end)
 {
 	struct veth_priv *priv = netdev_priv(dev);
 	int err, i;
 
-	for (i = 0; i < dev->real_num_rx_queues; i++) {
+	for (i = start; i < end; i++) {
 		struct veth_rq *rq = &priv->rq[i];
 
 		err = ptr_ring_init(&rq->xdp_ring, VETH_RING_SIZE, GFP_KERNEL);
@@ -939,7 +939,7 @@ static int __veth_napi_enable(struct net_device *dev)
 			goto err_xdp_ring;
 	}
 
-	for (i = 0; i < dev->real_num_rx_queues; i++) {
+	for (i = start; i < end; i++) {
 		struct veth_rq *rq = &priv->rq[i];
 
 		napi_enable(&rq->xdp_napi);
@@ -947,19 +947,25 @@ static int __veth_napi_enable(struct net_device *dev)
 	}
 
 	return 0;
+
 err_xdp_ring:
-	for (i--; i >= 0; i--)
+	for (i--; i >= start; i--)
 		ptr_ring_cleanup(&priv->rq[i].xdp_ring, veth_ptr_free);
 
 	return err;
 }
 
-static void veth_napi_del(struct net_device *dev)
+static int __veth_napi_enable(struct net_device *dev)
+{
+	return __veth_napi_enable_range(dev, 0, dev->real_num_rx_queues);
+}
+
+static void veth_napi_del_range(struct net_device *dev, int start, int end)
 {
 	struct veth_priv *priv = netdev_priv(dev);
 	int i;
 
-	for (i = 0; i < dev->real_num_rx_queues; i++) {
+	for (i = start; i < end; i++) {
 		struct veth_rq *rq = &priv->rq[i];
 
 		rcu_assign_pointer(priv->rq[i].napi, NULL);
@@ -968,7 +974,7 @@ static void veth_napi_del(struct net_device *dev)
 	}
 	synchronize_net();
 
-	for (i = 0; i < dev->real_num_rx_queues; i++) {
+	for (i = start; i < end; i++) {
 		struct veth_rq *rq = &priv->rq[i];
 
 		rq->rx_notify_masked = false;
@@ -976,41 +982,90 @@ static void veth_napi_del(struct net_device *dev)
 	}
 }
 
+static void veth_napi_del(struct net_device *dev)
+{
+	veth_napi_del_range(dev, 0, dev->real_num_rx_queues);
+}
+
 static bool veth_gro_requested(const struct net_device *dev)
 {
 	return !!(dev->wanted_features & NETIF_F_GRO);
 }
 
-static int veth_enable_xdp(struct net_device *dev)
+static int veth_enable_xdp_range(struct net_device *dev, int start, int end,
+				 bool napi_already_on)
 {
-	bool napi_already_on = veth_gro_requested(dev) && (dev->flags & IFF_UP);
 	struct veth_priv *priv = netdev_priv(dev);
 	int err, i;
 
-	if (!xdp_rxq_info_is_reg(&priv->rq[0].xdp_rxq)) {
-		for (i = 0; i < dev->real_num_rx_queues; i++) {
-			struct veth_rq *rq = &priv->rq[i];
+	for (i = start; i < end; i++) {
+		struct veth_rq *rq = &priv->rq[i];
 
-			if (!napi_already_on)
-				netif_napi_add(dev, &rq->xdp_napi, veth_poll, NAPI_POLL_WEIGHT);
-			err = xdp_rxq_info_reg(&rq->xdp_rxq, dev, i, rq->xdp_napi.napi_id);
-			if (err < 0)
-				goto err_rxq_reg;
+		if (!napi_already_on)
+			netif_napi_add(dev, &rq->xdp_napi, veth_poll, NAPI_POLL_WEIGHT);
+		err = xdp_rxq_info_reg(&rq->xdp_rxq, dev, i, rq->xdp_napi.napi_id);
+		if (err < 0)
+			goto err_rxq_reg;
 
-			err = xdp_rxq_info_reg_mem_model(&rq->xdp_rxq,
-							 MEM_TYPE_PAGE_SHARED,
-							 NULL);
-			if (err < 0)
-				goto err_reg_mem;
+		err = xdp_rxq_info_reg_mem_model(&rq->xdp_rxq,
+						 MEM_TYPE_PAGE_SHARED,
+						 NULL);
+		if (err < 0)
+			goto err_reg_mem;
 
-			/* Save original mem info as it can be overwritten */
-			rq->xdp_mem = rq->xdp_rxq.mem;
-		}
+		/* Save original mem info as it can be overwritten */
+		rq->xdp_mem = rq->xdp_rxq.mem;
+	}
+	return 0;
+
+err_reg_mem:
+	xdp_rxq_info_unreg(&priv->rq[i].xdp_rxq);
+err_rxq_reg:
+	for (i--; i >= start; i--) {
+		struct veth_rq *rq = &priv->rq[i];
+
+		xdp_rxq_info_unreg(&rq->xdp_rxq);
+		if (!napi_already_on)
+			netif_napi_del(&rq->xdp_napi);
+	}
+
+	return err;
+}
+
+static void veth_disable_xdp_range(struct net_device *dev, int start, int end,
+				   bool delete_napi)
+{
+	struct veth_priv *priv = netdev_priv(dev);
+	int i;
+
+	for (i = start; i < end; i++) {
+		struct veth_rq *rq = &priv->rq[i];
+
+		rq->xdp_rxq.mem = rq->xdp_mem;
+		xdp_rxq_info_unreg(&rq->xdp_rxq);
+
+		if (delete_napi)
+			netif_napi_del(&rq->xdp_napi);
+	}
+}
+
+static int veth_enable_xdp(struct net_device *dev)
+{
+	bool napi_already_on = veth_gro_requested(dev) && (dev->flags & IFF_UP);
+	struct veth_priv *priv = netdev_priv(dev);
+	int err, i;
+
+	if (!xdp_rxq_info_is_reg(&priv->rq[0].xdp_rxq)) {
+		err = veth_enable_xdp_range(dev, 0, dev->real_num_rx_queues, napi_already_on);
+		if (err)
+			return err;
 
 		if (!napi_already_on) {
 			err = __veth_napi_enable(dev);
-			if (err)
-				goto err_rxq_reg;
+			if (err) {
+				veth_disable_xdp_range(dev, 0, dev->real_num_rx_queues, true);
+				return err;
+			}
 
 			if (!veth_gro_requested(dev)) {
 				/* user-space did not require GRO, but adding XDP
@@ -1028,18 +1083,6 @@ static int veth_enable_xdp(struct net_device *dev)
 	}
 
 	return 0;
-err_reg_mem:
-	xdp_rxq_info_unreg(&priv->rq[i].xdp_rxq);
-err_rxq_reg:
-	for (i--; i >= 0; i--) {
-		struct veth_rq *rq = &priv->rq[i];
-
-		xdp_rxq_info_unreg(&rq->xdp_rxq);
-		if (!napi_already_on)
-			netif_napi_del(&rq->xdp_napi);
-	}
-
-	return err;
 }
 
 static void veth_disable_xdp(struct net_device *dev)
@@ -1062,28 +1105,23 @@ static void veth_disable_xdp(struct net_device *dev)
 		}
 	}
 
-	for (i = 0; i < dev->real_num_rx_queues; i++) {
-		struct veth_rq *rq = &priv->rq[i];
-
-		rq->xdp_rxq.mem = rq->xdp_mem;
-		xdp_rxq_info_unreg(&rq->xdp_rxq);
-	}
+	veth_disable_xdp_range(dev, 0, dev->real_num_rx_queues, false);
 }
 
-static int veth_napi_enable(struct net_device *dev)
+static int veth_napi_enable_range(struct net_device *dev, int start, int end)
 {
 	struct veth_priv *priv = netdev_priv(dev);
 	int err, i;
 
-	for (i = 0; i < dev->real_num_rx_queues; i++) {
+	for (i = start; i < end; i++) {
 		struct veth_rq *rq = &priv->rq[i];
 
 		netif_napi_add(dev, &rq->xdp_napi, veth_poll, NAPI_POLL_WEIGHT);
 	}
 
-	err = __veth_napi_enable(dev);
+	err = __veth_napi_enable_range(dev, start, end);
 	if (err) {
-		for (i = 0; i < dev->real_num_rx_queues; i++) {
+		for (i = start; i < end; i++) {
 			struct veth_rq *rq = &priv->rq[i];
 
 			netif_napi_del(&rq->xdp_napi);
@@ -1093,6 +1131,11 @@ static int veth_napi_enable(struct net_device *dev)
 	return err;
 }
 
+static int veth_napi_enable(struct net_device *dev)
+{
+	return veth_napi_enable_range(dev, 0, dev->real_num_rx_queues);
+}
+
 static int veth_open(struct net_device *dev)
 {
 	struct veth_priv *priv = netdev_priv(dev);