[PATCH v2 net-next 09/14] net: fec: use switch statement to check the type of tx_buf

[Wei Fang <wei.fang@nxp.com>]

The tx_buf has three types: FEC_TXBUF_T_SKB, FEC_TXBUF_T_XDP_NDO and
FEC_TXBUF_T_XDP_TX. Currently, the driver uses 'if...else...' statements
to check the type and perform the corresponding processing. This is very
detrimental to future expansion. To support AF_XDP zero-copy mode, two
new types will be added in the future, continuing to use 'if...else...'
would be a very bad coding style. So the 'if...else...' statements in
the current driver are replaced with switch statements.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
---
 drivers/net/ethernet/freescale/fec_main.c | 136 ++++++++++++----------
 1 file changed, 74 insertions(+), 62 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 0e8947f163a8..2f79ef195a9e 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1023,9 +1023,13 @@ static void fec_enet_bd_init(struct net_device *dev)
 		txq->bd.cur = bdp;
 
 		for (i = 0; i < txq->bd.ring_size; i++) {
+			struct page *page;
+
 			/* Initialize the BD for every fragment in the page. */
 			bdp->cbd_sc = cpu_to_fec16(0);
-			if (txq->tx_buf[i].type == FEC_TXBUF_T_SKB) {
+
+			switch (txq->tx_buf[i].type) {
+			case FEC_TXBUF_T_SKB:
 				if (bdp->cbd_bufaddr &&
 				    !IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
 					dma_unmap_single(&fep->pdev->dev,
@@ -1033,19 +1037,22 @@ static void fec_enet_bd_init(struct net_device *dev)
 							 fec16_to_cpu(bdp->cbd_datlen),
 							 DMA_TO_DEVICE);
 				dev_kfree_skb_any(txq->tx_buf[i].buf_p);
-			} else if (txq->tx_buf[i].type == FEC_TXBUF_T_XDP_NDO) {
+				break;
+			case FEC_TXBUF_T_XDP_NDO:
 				dma_unmap_single(&fep->pdev->dev,
 						 fec32_to_cpu(bdp->cbd_bufaddr),
 						 fec16_to_cpu(bdp->cbd_datlen),
 						 DMA_TO_DEVICE);
-
 				xdp_return_frame(txq->tx_buf[i].buf_p);
-			} else {
-				struct page *page = txq->tx_buf[i].buf_p;
-
+				break;
+			case FEC_TXBUF_T_XDP_TX:
+				page = txq->tx_buf[i].buf_p;
 				page_pool_put_page(pp_page_to_nmdesc(page)->pp,
 						   page, 0, false);
-			}
+				break;
+			default:
+				break;
+			};
 
 			txq->tx_buf[i].buf_p = NULL;
 			/* restore default tx buffer type: FEC_TXBUF_T_SKB */
@@ -1509,39 +1516,69 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget)
 			break;
 
 		index = fec_enet_get_bd_index(bdp, &txq->bd);
+		frame_len = fec16_to_cpu(bdp->cbd_datlen);
 
-		if (txq->tx_buf[index].type == FEC_TXBUF_T_SKB) {
-			skb = txq->tx_buf[index].buf_p;
+		switch (txq->tx_buf[index].type) {
+		case FEC_TXBUF_T_SKB:
 			if (bdp->cbd_bufaddr &&
 			    !IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
 				dma_unmap_single(&fep->pdev->dev,
 						 fec32_to_cpu(bdp->cbd_bufaddr),
-						 fec16_to_cpu(bdp->cbd_datlen),
-						 DMA_TO_DEVICE);
+						 frame_len, DMA_TO_DEVICE);
+
 			bdp->cbd_bufaddr = cpu_to_fec32(0);
+			skb = txq->tx_buf[index].buf_p;
 			if (!skb)
 				goto tx_buf_done;
-		} else {
+
+			frame_len = skb->len;
+
+			/* NOTE: SKBTX_IN_PROGRESS being set does not imply it's we who
+			 * are to time stamp the packet, so we still need to check time
+			 * stamping enabled flag.
+			 */
+			if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS &&
+				     fep->hwts_tx_en) && fep->bufdesc_ex) {
+				struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
+				struct skb_shared_hwtstamps shhwtstamps;
+
+				fec_enet_hwtstamp(fep, fec32_to_cpu(ebdp->ts), &shhwtstamps);
+				skb_tstamp_tx(skb, &shhwtstamps);
+			}
+
+			/* Free the sk buffer associated with this last transmit */
+			napi_consume_skb(skb, budget);
+			break;
+		case FEC_TXBUF_T_XDP_NDO:
 			/* Tx processing cannot call any XDP (or page pool) APIs if
 			 * the "budget" is 0. Because NAPI is called with budget of
 			 * 0 (such as netpoll) indicates we may be in an IRQ context,
 			 * however, we can't use the page pool from IRQ context.
 			 */
 			if (unlikely(!budget))
-				break;
+				goto out;
 
-			if (txq->tx_buf[index].type == FEC_TXBUF_T_XDP_NDO) {
-				xdpf = txq->tx_buf[index].buf_p;
-				dma_unmap_single(&fep->pdev->dev,
-						 fec32_to_cpu(bdp->cbd_bufaddr),
-						 fec16_to_cpu(bdp->cbd_datlen),
-						 DMA_TO_DEVICE);
-			} else {
-				page = txq->tx_buf[index].buf_p;
-			}
+			xdpf = txq->tx_buf[index].buf_p;
+			dma_unmap_single(&fep->pdev->dev,
+					 fec32_to_cpu(bdp->cbd_bufaddr),
+					 frame_len,  DMA_TO_DEVICE);
+			bdp->cbd_bufaddr = cpu_to_fec32(0);
+			xdp_return_frame_rx_napi(xdpf);
+			break;
+		case FEC_TXBUF_T_XDP_TX:
+			if (unlikely(!budget))
+				goto out;
 
 			bdp->cbd_bufaddr = cpu_to_fec32(0);
-			frame_len = fec16_to_cpu(bdp->cbd_datlen);
+			page = txq->tx_buf[index].buf_p;
+			/* The dma_sync_size = 0 as XDP_TX has already synced
+			 * DMA for_device
+			 */
+			page_pool_put_page(pp_page_to_nmdesc(page)->pp, page,
+					   0, true);
+			break;
+		default:
+			break;
 		}
 
 		/* Check for errors. */
@@ -1561,11 +1598,7 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget)
 				ndev->stats.tx_carrier_errors++;
 		} else {
 			ndev->stats.tx_packets++;
-
-			if (txq->tx_buf[index].type == FEC_TXBUF_T_SKB)
-				ndev->stats.tx_bytes += skb->len;
-			else
-				ndev->stats.tx_bytes += frame_len;
+			ndev->stats.tx_bytes += frame_len;
 		}
 
 		/* Deferred means some collisions occurred during transmit,
@@ -1574,30 +1607,6 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget)
 		if (status & BD_ENET_TX_DEF)
 			ndev->stats.collisions++;
 
-		if (txq->tx_buf[index].type == FEC_TXBUF_T_SKB) {
-			/* NOTE: SKBTX_IN_PROGRESS being set does not imply it's we who
-			 * are to time stamp the packet, so we still need to check time
-			 * stamping enabled flag.
-			 */
-			if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS &&
-				     fep->hwts_tx_en) && fep->bufdesc_ex) {
-				struct skb_shared_hwtstamps shhwtstamps;
-				struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
-
-				fec_enet_hwtstamp(fep, fec32_to_cpu(ebdp->ts), &shhwtstamps);
-				skb_tstamp_tx(skb, &shhwtstamps);
-			}
-
-			/* Free the sk buffer associated with this last transmit */
-			napi_consume_skb(skb, budget);
-		} else if (txq->tx_buf[index].type == FEC_TXBUF_T_XDP_NDO) {
-			xdp_return_frame_rx_napi(xdpf);
-		} else { /* recycle pages of XDP_TX frames */
-			/* The dma_sync_size = 0 as XDP_TX has already synced DMA for_device */
-			page_pool_put_page(pp_page_to_nmdesc(page)->pp, page,
-					   0, true);
-		}
-
 		txq->tx_buf[index].buf_p = NULL;
 		/* restore default tx buffer type: FEC_TXBUF_T_SKB */
 		txq->tx_buf[index].type = FEC_TXBUF_T_SKB;
@@ -1621,6 +1630,8 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id, int budget)
 		}
 	}
 
+out:
+
 	/* ERR006358: Keep the transmitter going */
 	if (bdp != txq->bd.cur &&
 	    readl(txq->bd.reg_desc_active) == 0)
@@ -3414,6 +3425,7 @@ static void fec_enet_free_buffers(struct net_device *ndev)
 	unsigned int i;
 	struct fec_enet_priv_tx_q *txq;
 	struct fec_enet_priv_rx_q *rxq;
+	struct page *page;
 	unsigned int q;
 
 	for (q = 0; q < fep->num_rx_queues; q++) {
@@ -3437,20 +3449,20 @@ static void fec_enet_free_buffers(struct net_device *ndev)
 			kfree(txq->tx_bounce[i]);
 			txq->tx_bounce[i] = NULL;
 
-			if (!txq->tx_buf[i].buf_p) {
-				txq->tx_buf[i].type = FEC_TXBUF_T_SKB;
-				continue;
-			}
-
-			if (txq->tx_buf[i].type == FEC_TXBUF_T_SKB) {
+			switch (txq->tx_buf[i].type) {
+			case FEC_TXBUF_T_SKB:
 				dev_kfree_skb(txq->tx_buf[i].buf_p);
-			} else if (txq->tx_buf[i].type == FEC_TXBUF_T_XDP_NDO) {
+				break;
+			case FEC_TXBUF_T_XDP_NDO:
 				xdp_return_frame(txq->tx_buf[i].buf_p);
-			} else {
-				struct page *page = txq->tx_buf[i].buf_p;
-
+				break;
+			case FEC_TXBUF_T_XDP_TX:
+				page = txq->tx_buf[i].buf_p;
 				page_pool_put_page(pp_page_to_nmdesc(page)->pp,
 						   page, 0, false);
+				break;
+			default:
+				break;
 			}
 
 			txq->tx_buf[i].buf_p = NULL;
-- 
2.34.1