mlx4: do not access rx_desc from mlx4_en_process_rx_cq()

Instead of fetching dma address from rx_desc->data[0].addr,
prefer using frags[0].dma + frags[0].page_offset to avoid
a potential cache line miss.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-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 d3a425f..b62fa26 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -528,7 +528,6 @@ fail:
 
 
 static struct sk_buff *mlx4_en_rx_skb(struct mlx4_en_priv *priv,
-                                     struct mlx4_en_rx_desc *rx_desc,
                                      struct mlx4_en_rx_alloc *frags,
                                      unsigned int length)
 {
@@ -703,7 +702,6 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
        struct mlx4_cqe *cqe;
        struct mlx4_en_rx_ring *ring = priv->rx_ring[cq->ring];
        struct mlx4_en_rx_alloc *frags;
-       struct mlx4_en_rx_desc *rx_desc;
        struct bpf_prog *xdp_prog;
        int doorbell_pending;
        struct sk_buff *skb;
@@ -738,7 +736,6 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
                    cq->mcq.cons_index & cq->size)) {
 
                frags = ring->rx_info + (index << priv->log_rx_info);
-               rx_desc = ring->buf + (index << ring->log_stride);
 
                /*
                 * make sure we read the CQE after we read the ownership bit
@@ -767,7 +764,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
                        /* Get pointer to first fragment since we haven't
                         * skb yet and cast it to ethhdr struct
                         */
-                       dma = be64_to_cpu(rx_desc->data[0].addr);
+                       dma = frags[0].dma + frags[0].page_offset;
                        dma_sync_single_for_cpu(priv->ddev, dma, sizeof(*ethh),
                                                DMA_FROM_DEVICE);
                        ethh = (struct ethhdr *)(page_address(frags[0].page) +
@@ -806,7 +803,7 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
                        void *orig_data;
                        u32 act;
 
-                       dma = be64_to_cpu(rx_desc->data[0].addr);
+                       dma = frags[0].dma + frags[0].page_offset;
                        dma_sync_single_for_cpu(priv->ddev, dma,
                                                priv->frag_info[0].frag_size,
                                                DMA_FROM_DEVICE);
@@ -946,7 +943,7 @@ xdp_drop_no_cnt:
                }
 
                /* GRO not possible, complete processing here */
-               skb = mlx4_en_rx_skb(priv, rx_desc, frags, length);
+               skb = mlx4_en_rx_skb(priv, frags, length);
                if (unlikely(!skb)) {
                        ring->dropped++;
                        goto next;