net/mlx4_en: Add branch prediction hints in RX data-path

Add likely/unlikely hints to improve branch predictions
in the RX data-path.

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index c46355b..6e474af 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -72,7 +72,7 @@ static int mlx4_alloc_pages(struct mlx4_en_priv *priv,
        }
        dma = dma_map_page(priv->ddev, page, 0, PAGE_SIZE << order,
                           frag_info->dma_dir);
-       if (dma_mapping_error(priv->ddev, dma)) {
+       if (unlikely(dma_mapping_error(priv->ddev, dma))) {
                put_page(page);
                return -ENOMEM;
        }
@@ -108,7 +108,8 @@ static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
                    ring_alloc[i].page_size)
                        continue;
 
-               if (mlx4_alloc_pages(priv, &page_alloc[i], frag_info, gfp))
+               if (unlikely(mlx4_alloc_pages(priv, &page_alloc[i],
+                                             frag_info, gfp)))
                        goto out;
        }
 
@@ -585,7 +586,7 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv,
                frag_info = &priv->frag_info[nr];
                if (length <= frag_info->frag_prefix_size)
                        break;
-               if (!frags[nr].page)
+               if (unlikely(!frags[nr].page))
                        goto fail;
 
                dma = be64_to_cpu(rx_desc->data[nr].addr);
@@ -625,7 +626,7 @@ static struct sk_buff *mlx4_en_rx_skb(struct mlx4_en_priv *priv,
        dma_addr_t dma;
 
        skb = netdev_alloc_skb(priv->dev, SMALL_PACKET_SIZE + NET_IP_ALIGN);
-       if (!skb) {
+       if (unlikely(!skb)) {
                en_dbg(RX_ERR, priv, "Failed allocating skb\n");
                return NULL;
        }
@@ -736,7 +737,8 @@ static int get_fixed_ipv6_csum(__wsum hw_checksum, struct sk_buff *skb,
 {
        __wsum csum_pseudo_hdr = 0;
 
-       if (ipv6h->nexthdr == IPPROTO_FRAGMENT || ipv6h->nexthdr == IPPROTO_HOPOPTS)
+       if (unlikely(ipv6h->nexthdr == IPPROTO_FRAGMENT ||
+                    ipv6h->nexthdr == IPPROTO_HOPOPTS))
                return -1;
        hw_checksum = csum_add(hw_checksum, (__force __wsum)htons(ipv6h->nexthdr));
 
@@ -769,7 +771,7 @@ static int check_csum(struct mlx4_cqe *cqe, struct sk_buff *skb, void *va,
                get_fixed_ipv4_csum(hw_checksum, skb, hdr);
 #if IS_ENABLED(CONFIG_IPV6)
        else if (cqe->status & cpu_to_be16(MLX4_CQE_STATUS_IPV6))
-               if (get_fixed_ipv6_csum(hw_checksum, skb, hdr))
+               if (unlikely(get_fixed_ipv6_csum(hw_checksum, skb, hdr)))
                        return -1;
 #endif
        return 0;
@@ -796,10 +798,10 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
        u64 timestamp;
        bool l2_tunnel;
 
-       if (!priv->port_up)
+       if (unlikely(!priv->port_up))
                return 0;
 
-       if (budget <= 0)
+       if (unlikely(budget <= 0))
                return polled;
 
        /* Protect accesses to: ring->xdp_prog, priv->mac_hash list */
@@ -902,9 +904,9 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
                        case XDP_PASS:
                                break;
                        case XDP_TX:
-                               if (!mlx4_en_xmit_frame(frags, dev,
+                               if (likely(!mlx4_en_xmit_frame(frags, dev,
                                                        length, tx_index,
-                                                       &doorbell_pending))
+                                                       &doorbell_pending)))
                                        goto consumed;
                                goto xdp_drop; /* Drop on xmit failure */
                        default:
@@ -912,7 +914,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
                        case XDP_ABORTED:
                        case XDP_DROP:
 xdp_drop:
-                               if (mlx4_en_rx_recycle(ring, frags))
+                               if (likely(mlx4_en_rx_recycle(ring, frags)))
                                        goto consumed;
                                goto next;
                        }
@@ -1016,7 +1018,7 @@ xdp_drop:
 
                /* GRO not possible, complete processing here */
                skb = mlx4_en_rx_skb(priv, rx_desc, frags, length);
-               if (!skb) {
+               if (unlikely(!skb)) {
                        ring->dropped++;
                        goto next;
                }