netdev - [net-next PATCH 2/7] mlx4: use napi_consume_skb API to get bulk free operations

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Message-ID: <20160304130133.32651.55278.stgit@firesoul>
Date:	Fri, 04 Mar 2016 14:01:33 +0100
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Cc:	eugenia@...lanox.com, Alexander Duyck <alexander.duyck@...il.com>,
	alexei.starovoitov@...il.com, saeedm@...lanox.com,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	gerlitz.or@...il.com
Subject: [net-next PATCH 2/7] mlx4: use napi_consume_skb API to get bulk
 free operations

Bulk free of SKBs happen transparently by the API call napi_consume_skb().
The napi budget parameter is needed by napi_consume_skb() to detect
if called from netpoll.

For mlx4 driver, the mlx4_en_stop_port() call cleanup the entire
TX ring via mlx4_en_free_tx_buf().  To handle this situation,
napi budget value -1 is used for indicating this call happens
outside NAPI context.  To reflect this, variable is called napi_mode
for the function call that needed this distinction.

Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_tx.c |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index e0946ab22010..b94ed84646b0 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -276,7 +276,8 @@ static void mlx4_en_stamp_wqe(struct mlx4_en_priv *priv,
 
 static u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
 				struct mlx4_en_tx_ring *ring,
-				int index, u8 owner, u64 timestamp)
+				int index, u8 owner, u64 timestamp,
+				int napi_mode)
 {
 	struct mlx4_en_tx_info *tx_info = &ring->tx_info[index];
 	struct mlx4_en_tx_desc *tx_desc = ring->buf + index * TXBB_SIZE;
@@ -347,7 +348,11 @@ static u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
 			}
 		}
 	}
-	dev_consume_skb_any(skb);
+	if (unlikely(napi_mode < 0))
+		dev_consume_skb_any(skb); /* none-NAPI via mlx4_en_stop_port */
+	else
+		napi_consume_skb(skb, napi_mode);
+
 	return tx_info->nr_txbb;
 }
 
@@ -371,7 +376,9 @@ int mlx4_en_free_tx_buf(struct net_device *dev, struct mlx4_en_tx_ring *ring)
 	while (ring->cons != ring->prod) {
 		ring->last_nr_txbb = mlx4_en_free_tx_desc(priv, ring,
 						ring->cons & ring->size_mask,
-						!!(ring->cons & ring->size), 0);
+						!!(ring->cons & ring->size), 0,
+						-1 /* none-NAPI caller */
+			);
 		ring->cons += ring->last_nr_txbb;
 		cnt++;
 	}
@@ -385,7 +392,7 @@ int mlx4_en_free_tx_buf(struct net_device *dev, struct mlx4_en_tx_ring *ring)
 }
 
 static bool mlx4_en_process_tx_cq(struct net_device *dev,
-				 struct mlx4_en_cq *cq)
+				  struct mlx4_en_cq *cq, int napi_budget)
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 	struct mlx4_cq *mcq = &cq->mcq;
@@ -451,7 +458,7 @@ static bool mlx4_en_process_tx_cq(struct net_device *dev,
 			last_nr_txbb = mlx4_en_free_tx_desc(
 					priv, ring, ring_index,
 					!!((ring_cons + txbbs_skipped) &
-					ring->size), timestamp);
+					ring->size), timestamp, napi_budget);
 
 			mlx4_en_stamp_wqe(priv, ring, stamp_index,
 					  !!((ring_cons + txbbs_stamp) &
@@ -511,7 +518,7 @@ int mlx4_en_poll_tx_cq(struct napi_struct *napi, int budget)
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 	int clean_complete;
 
-	clean_complete = mlx4_en_process_tx_cq(dev, cq);
+	clean_complete = mlx4_en_process_tx_cq(dev, cq, budget);
 	if (!clean_complete)
 		return budget;