net/mlx4_en: Code cleanups in tx path

- Remove unused variable ring->poll_cnt
- No need to set some fields if using blueflame
- Add missing const's
- Use unlikely
- Remove unneeded new line
- Make some comments more precise
- struct mlx4_bf @offset field reduced to unsigned int to save space

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 27 insertions, 25 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index 0c501253fdab..eaf23eb7266a 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -191,7 +191,6 @@ int mlx4_en_activate_tx_ring(struct mlx4_en_priv *priv,
         ring->prod = 0;
         ring->cons = 0xffffffff;
         ring->last_nr_txbb = 1;
-        ring->poll_cnt = 0;
         memset(ring->tx_info, 0, ring->size * sizeof(struct mlx4_en_tx_info));
         memset(ring->buf, 0, ring->buf_size);
 
@@ -512,7 +511,8 @@ static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv,
         return ring->buf + index * TXBB_SIZE;
 }
 
-static int is_inline(int inline_thold, struct sk_buff *skb, void **pfrag)
+static bool is_inline(int inline_thold, const struct sk_buff *skb,
+                      void **pfrag)
 {
         void *ptr;
 
@@ -535,7 +535,7 @@ static int is_inline(int inline_thold, struct sk_buff *skb, void **pfrag)
         return 0;
 }
 
-static int inline_size(struct sk_buff *skb)
+static int inline_size(const struct sk_buff *skb)
 {
         if (skb->len + CTRL_SIZE + sizeof(struct mlx4_wqe_inline_seg)
             <= MLX4_INLINE_ALIGN)
@@ -546,7 +546,8 @@ static int inline_size(struct sk_buff *skb)
                              sizeof(struct mlx4_wqe_inline_seg), 16);
 }
 
-static int get_real_size(struct sk_buff *skb, struct net_device *dev,
+static int get_real_size(const struct sk_buff *skb,
+                         struct net_device *dev,
                          int *lso_header_size)
 {
         struct mlx4_en_priv *priv = netdev_priv(dev);
@@ -581,8 +582,10 @@ static int get_real_size(struct sk_buff *skb, struct net_device *dev,
         return real_size;
 }
 
-static void build_inline_wqe(struct mlx4_en_tx_desc *tx_desc, struct sk_buff *skb,
-                             int real_size, u16 *vlan_tag, int tx_ind, void *fragptr)
+static void build_inline_wqe(struct mlx4_en_tx_desc *tx_desc,
+                             const struct sk_buff *skb,
+                             int real_size, u16 *vlan_tag,
+                             int tx_ind, void *fragptr)
 {
         struct mlx4_wqe_inline_seg *inl = &tx_desc->inl;
         int spc = MLX4_INLINE_ALIGN - CTRL_SIZE - sizeof *inl;
@@ -642,7 +645,8 @@ u16 mlx4_en_select_queue(struct net_device *dev, struct sk_buff *skb,
         return fallback(dev, skb) % rings_p_up + up * rings_p_up;
 }
 
-static void mlx4_bf_copy(void __iomem *dst, unsigned long *src, unsigned bytecnt)
+static void mlx4_bf_copy(void __iomem *dst, const void *src,
+                         unsigned int bytecnt)
 {
         __iowrite64_copy(dst, src, bytecnt / 8);
 }
@@ -736,11 +740,10 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
         tx_info->skb = skb;
         tx_info->nr_txbb = nr_txbb;
 
+        data = &tx_desc->data;
         if (lso_header_size)
                 data = ((void *)&tx_desc->lso + ALIGN(lso_header_size + 4,
                                                       DS_SIZE));
-        else
-                data = &tx_desc->data;
 
         /* valid only for none inline segments */
         tx_info->data_offset = (void *)data - (void *)tx_desc;
@@ -753,9 +756,9 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
         if (is_inline(ring->inline_thold, skb, &fragptr)) {
                 tx_info->inl = 1;
         } else {
-                /* Map fragments */
+                /* Map fragments if any */
                 for (i = skb_shinfo(skb)->nr_frags - 1; i >= 0; i--) {
-                        struct skb_frag_struct *frag;
+                        const struct skb_frag_struct *frag;
                         dma_addr_t dma;
 
                         frag = &skb_shinfo(skb)->frags[i];
@@ -772,7 +775,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
                         --data;
                 }
 
-                /* Map linear part */
+                /* Map linear part if needed */
                 if (tx_info->linear) {
                         u32 byte_count = skb_headlen(skb) - lso_header_size;
                         dma_addr_t dma;
@@ -795,18 +798,14 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
          * For timestamping add flag to skb_shinfo and
          * set flag for further reference
          */
-        if (ring->hwtstamp_tx_type == HWTSTAMP_TX_ON &&
-            skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) {
-                skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
+        if (unlikely(ring->hwtstamp_tx_type == HWTSTAMP_TX_ON &&
+                     shinfo->tx_flags & SKBTX_HW_TSTAMP)) {
+                shinfo->tx_flags |= SKBTX_IN_PROGRESS;
                 tx_info->ts_requested = 1;
         }
 
         /* Prepare ctrl segement apart opcode+ownership, which depends on
          * whether LSO is used */
-        tx_desc->ctrl.vlan_tag = cpu_to_be16(vlan_tag);
-        tx_desc->ctrl.ins_vlan = MLX4_WQE_CTRL_INS_VLAN *
-                !!vlan_tx_tag_present(skb);
-        tx_desc->ctrl.fence_size = (real_size / 16) & 0x3f;
         tx_desc->ctrl.srcrb_flags = priv->ctrl_flags;
         if (likely(skb->ip_summed == CHECKSUM_PARTIAL)) {
                 tx_desc->ctrl.srcrb_flags |= cpu_to_be32(MLX4_WQE_CTRL_IP_CSUM |
@@ -852,7 +851,6 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
                          cpu_to_be32(MLX4_EN_BIT_DESC_OWN) : 0);
                 tx_info->nr_bytes = max_t(unsigned int, skb->len, ETH_ZLEN);
                 ring->packets++;
-
         }
         ring->bytes += tx_info->nr_bytes;
         netdev_tx_sent_queue(ring->tx_queue, tx_info->nr_bytes);
@@ -874,7 +872,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
         ring->prod += nr_txbb;
 
         /* If we used a bounce buffer then copy descriptor back into place */
-        if (bounce)
+        if (unlikely(bounce))
                 tx_desc = mlx4_en_bounce_to_desc(priv, ring, index, desc_size);
 
         skb_tx_timestamp(skb);
@@ -894,13 +892,18 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
 
                 wmb();
 
-                mlx4_bf_copy(ring->bf.reg + ring->bf.offset, (unsigned long *) &tx_desc->ctrl,
-                     desc_size);
+                mlx4_bf_copy(ring->bf.reg + ring->bf.offset, &tx_desc->ctrl,
+                             desc_size);
 
                 wmb();
 
                 ring->bf.offset ^= ring->bf.buf_size;
         } else {
+                tx_desc->ctrl.vlan_tag = cpu_to_be16(vlan_tag);
+                tx_desc->ctrl.ins_vlan = MLX4_WQE_CTRL_INS_VLAN *
+                        !!vlan_tx_tag_present(skb);
+                tx_desc->ctrl.fence_size = real_size;
+
                 /* Ensure new descriptor hits memory
                  * before setting ownership of this descriptor to HW
                  */
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index 84c9d5dbfa4f..e54b653de3d4 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -263,7 +263,6 @@ struct mlx4_en_tx_ring {
         u32 buf_size;
         u32 doorbell_qpn;
         void *buf;
-        u16 poll_cnt;
         struct mlx4_en_tx_info *tx_info;
         u8 *bounce_buf;
         u8 queue_index;
diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index b2f8ab9a57c4..37e4404d0227 100644
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h
@@ -583,7 +583,7 @@ struct mlx4_uar {
 };
 
 struct mlx4_bf {
-        unsigned long           offset;
+        unsigned int            offset;
         int                     buf_size;
         struct mlx4_uar        *uar;
         void __iomem           *reg;