net: remove skb recycling

Over time, skb recycling infrastructure got litle interest and
many bugs. Generic rx path skb allocation is now using page
fragments for efficient GRO / TCP coalescing, and recyling
a tx skb for rx path is not worth the pain.

Last identified bug is that fat skbs can be recycled
and it can endup using high order pages after few iterations.

With help from Maxime Bizon, who pointed out that commit
87151b8689d (net: allow pskb_expand_head() to get maximum tailroom)
introduced this regression for recycled skbs.

Instead of fixing this bug, lets remove skb recycling.

Drivers wanting really hot skbs should use build_skb() anyway,
to allocate/populate sk_buff right before netif_receive_skb()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 23 deletions

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index a1b52ec3b930..1d03dcdd5e56 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -1765,7 +1765,6 @@ static void free_skb_resources(struct gfar_private *priv)
 			  sizeof(struct rxbd8) * priv->total_rx_ring_size,
 			  priv->tx_queue[0]->tx_bd_base,
 			  priv->tx_queue[0]->tx_bd_dma_base);
-	skb_queue_purge(&priv->rx_recycle);
 }
 
 void gfar_start(struct net_device *dev)
@@ -1943,8 +1942,6 @@ static int gfar_enet_open(struct net_device *dev)
 
 	enable_napi(priv);
 
-	skb_queue_head_init(&priv->rx_recycle);
-
 	/* Initialize a bunch of registers */
 	init_registers(dev);
 
@@ -2533,16 +2530,7 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
 
 		bytes_sent += skb->len;
 
-		/* If there's room in the queue (limit it to rx_buffer_size)
-		 * we add this skb back into the pool, if it's the right size
-		 */
-		if (skb_queue_len(&priv->rx_recycle) < rx_queue->rx_ring_size &&
-		    skb_recycle_check(skb, priv->rx_buffer_size +
-				      RXBUF_ALIGNMENT)) {
-			gfar_align_skb(skb);
-			skb_queue_head(&priv->rx_recycle, skb);
-		} else
-			dev_kfree_skb_any(skb);
+		dev_kfree_skb_any(skb);
 
 		tx_queue->tx_skbuff[skb_dirtytx] = NULL;
 
@@ -2608,7 +2596,7 @@ static void gfar_new_rxbdp(struct gfar_priv_rx_q *rx_queue, struct rxbd8 *bdp,
 static struct sk_buff *gfar_alloc_skb(struct net_device *dev)
 {
 	struct gfar_private *priv = netdev_priv(dev);
-	struct sk_buff *skb = NULL;
+	struct sk_buff *skb;
 
 	skb = netdev_alloc_skb(dev, priv->rx_buffer_size + RXBUF_ALIGNMENT);
 	if (!skb)
@@ -2621,14 +2609,7 @@ static struct sk_buff *gfar_alloc_skb(struct net_device *dev)
 
 struct sk_buff *gfar_new_skb(struct net_device *dev)
 {
-	struct gfar_private *priv = netdev_priv(dev);
-	struct sk_buff *skb = NULL;
-
-	skb = skb_dequeue(&priv->rx_recycle);
-	if (!skb)
-		skb = gfar_alloc_skb(dev);
-
-	return skb;
+	return gfar_alloc_skb(dev);
 }
 
 static inline void count_errors(unsigned short status, struct net_device *dev)
@@ -2787,7 +2768,7 @@ int gfar_clean_rx_ring(struct gfar_priv_rx_q *rx_queue, int rx_work_limit)
 			if (unlikely(!newskb))
 				newskb = skb;
 			else if (skb)
-				skb_queue_head(&priv->rx_recycle, skb);
+				dev_kfree_skb(skb);
 		} else {
 			/* Increment the number of packets */
 			rx_queue->stats.rx_packets++;