netdev - [PATCH net-next 1/4] net/mlx4_en: RX csum, remove redundant branches and checks

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Date:   Thu, 28 Dec 2017 16:26:08 +0200
From:   Tariq Toukan <tariqt@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Eran Ben Elisha <eranbe@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>
Subject: [PATCH net-next 1/4] net/mlx4_en: RX csum, remove redundant branches and checks

Do not check IPv6 bit in cqe status if CONFIG_IPV6 is not enabled.
Function check_csum() is reached only with IPv4 or IPv6 set (if enabled),
if IPv6 is not set (or is not enabled) it is redundant to test the
IPv4 bit.

Signed-off-by: Tariq Toukan <tariqt@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_rx.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 85e28efcda33..680bd3fbaa60 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -617,6 +617,10 @@ static int get_fixed_ipv6_csum(__wsum hw_checksum, struct sk_buff *skb,
 	return 0;
 }
 #endif
+
+/* We reach this function only after checking that any of
+ * the (IPv4 | IPv6) bits are set in cqe->status.
+ */
 static int check_csum(struct mlx4_cqe *cqe, struct sk_buff *skb, void *va,
 		      netdev_features_t dev_features)
 {
@@ -632,13 +636,11 @@ static int check_csum(struct mlx4_cqe *cqe, struct sk_buff *skb, void *va,
 		hdr += sizeof(struct vlan_hdr);
 	}
 
-	if (cqe->status & cpu_to_be16(MLX4_CQE_STATUS_IPV4))
-		return get_fixed_ipv4_csum(hw_checksum, skb, hdr);
 #if IS_ENABLED(CONFIG_IPV6)
 	if (cqe->status & cpu_to_be16(MLX4_CQE_STATUS_IPV6))
 		return get_fixed_ipv6_csum(hw_checksum, skb, hdr);
 #endif
-	return 0;
+	return get_fixed_ipv4_csum(hw_checksum, skb, hdr);
 }
 
 int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int budget)
@@ -830,7 +832,11 @@ int mlx4_en_process_rx_cq(struct net_device *dev, struct mlx4_en_cq *cq, int bud
 			} else {
 				if (priv->flags & MLX4_EN_FLAG_RX_CSUM_NON_TCP_UDP &&
 				    (cqe->status & cpu_to_be16(MLX4_CQE_STATUS_IPV4 |
+#if IS_ENABLED(CONFIG_IPV6)
 							       MLX4_CQE_STATUS_IPV6))) {
+#else
+							       0))) {
+#endif
 					if (check_csum(cqe, skb, va, dev->features)) {
 						goto csum_none;
 					} else {
-- 
1.8.3.1