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>

2 files changed, 2 insertions, 19 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index e872e1da3137..7d51a65ab099 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -50,7 +50,6 @@ struct stmmac_priv {
         unsigned int dirty_rx;
         struct sk_buff **rx_skbuff;
         dma_addr_t *rx_skbuff_dma;
-        struct sk_buff_head rx_recycle;
 
         struct net_device *dev;
         dma_addr_t dma_rx_phy;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 3be88331d17a..c6cdbc4eb05e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -747,18 +747,7 @@ static void stmmac_tx(struct stmmac_priv *priv)
                 priv->hw->ring->clean_desc3(p);
 
                 if (likely(skb != NULL)) {
-                        /*
-                         * If there's room in the queue (limit it to size)
-                         * we add this skb back into the pool,
-                         * if it's the right size.
-                         */
-                        if ((skb_queue_len(&priv->rx_recycle) <
-                                priv->dma_rx_size) &&
-                                skb_recycle_check(skb, priv->dma_buf_sz))
-                                __skb_queue_head(&priv->rx_recycle, skb);
-                        else
-                                dev_kfree_skb(skb);
-
+                        dev_kfree_skb(skb);
                         priv->tx_skbuff[entry] = NULL;
                 }
 
@@ -1169,7 +1158,6 @@ static int stmmac_open(struct net_device *dev)
         priv->eee_enabled = stmmac_eee_init(priv);
 
         napi_enable(&priv->napi);
-        skb_queue_head_init(&priv->rx_recycle);
         netif_start_queue(dev);
 
         return 0;
@@ -1222,7 +1210,6 @@ static int stmmac_release(struct net_device *dev)
                 kfree(priv->tm);
 #endif
         napi_disable(&priv->napi);
-        skb_queue_purge(&priv->rx_recycle);
 
         /* Free the IRQ lines */
         free_irq(dev->irq, dev);
@@ -1388,10 +1375,7 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv)
                 if (likely(priv->rx_skbuff[entry] == NULL)) {
                         struct sk_buff *skb;
 
-                        skb = __skb_dequeue(&priv->rx_recycle);
-                        if (skb == NULL)
-                                skb = netdev_alloc_skb_ip_align(priv->dev,
-                                                                bfsize);
+                        skb = netdev_alloc_skb_ip_align(priv->dev, bfsize);
 
                         if (unlikely(skb == NULL))
                                 break;