sky2: skb recycling

This patch implements skb recycling. It reclaims transmitted skb's
for use in the receive ring.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 28 insertions, 11 deletions

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index 6e95d2f54106..4f2afc770f8f 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -1176,6 +1176,7 @@ static void sky2_rx_clean(struct sky2_port *sky2)
                         re->skb = NULL;
                 }
         }
+        skb_queue_purge(&sky2->rx_recycle);
 }
 
 /* Basic MII support */
@@ -1252,6 +1253,12 @@ static void sky2_vlan_rx_register(struct net_device *dev, struct vlan_group *grp
 }
 #endif
 
+/* Amount of required worst case padding in rx buffer */
+static inline unsigned sky2_rx_pad(const struct sky2_hw *hw)
+{
+        return (hw->flags & SKY2_HW_RAM_BUFFER) ? 8 : 2;
+}
+
 /*
  * Allocate an skb for receiving. If the MTU is large enough
  * make the skb non-linear with a fragment list of pages.
@@ -1261,6 +1268,13 @@ static struct sk_buff *sky2_rx_alloc(struct sky2_port *sky2)
         struct sk_buff *skb;
         int i;
 
+        skb = __skb_dequeue(&sky2->rx_recycle);
+        if (!skb)
+                skb = netdev_alloc_skb(sky2->netdev, sky2->rx_data_size
+                                       + sky2_rx_pad(sky2->hw));
+        if (!skb)
+                goto nomem;
+
         if (sky2->hw->flags & SKY2_HW_RAM_BUFFER) {
                 unsigned char *start;
                 /*
@@ -1269,18 +1283,10 @@ static struct sk_buff *sky2_rx_alloc(struct sky2_port *sky2)
                  * The buffer returned from netdev_alloc_skb is
                  * aligned except if slab debugging is enabled.
                  */
-                skb = netdev_alloc_skb(sky2->netdev, sky2->rx_data_size + 8);
-                if (!skb)
-                        goto nomem;
                 start = PTR_ALIGN(skb->data, 8);
                 skb_reserve(skb, start - skb->data);
-        } else {
-                skb = netdev_alloc_skb(sky2->netdev,
-                                       sky2->rx_data_size + NET_IP_ALIGN);
-                if (!skb)
-                        goto nomem;
+        } else
                 skb_reserve(skb, NET_IP_ALIGN);
-        }
 
         for (i = 0; i < sky2->rx_nfrags; i++) {
                 struct page *page = alloc_page(GFP_ATOMIC);
@@ -1357,6 +1363,8 @@ static int sky2_rx_start(struct sky2_port *sky2)
 
         sky2->rx_data_size = size;
 
+        skb_queue_head_init(&sky2->rx_recycle);
+
         /* Fill Rx ring */
         for (i = 0; i < sky2->rx_pending; i++) {
                 re = sky2->rx_ring + i;
@@ -1764,14 +1772,22 @@ static void sky2_tx_complete(struct sky2_port *sky2, u16 done)
                 }
 
                 if (le->ctrl & EOP) {
+                        struct sk_buff *skb = re->skb;
+
                         if (unlikely(netif_msg_tx_done(sky2)))
                                 printk(KERN_DEBUG "%s: tx done %u\n",
                                        dev->name, idx);
 
                         dev->stats.tx_packets++;
-                        dev->stats.tx_bytes += re->skb->len;
+                        dev->stats.tx_bytes += skb->len;
+
+                        if (skb_queue_len(&sky2->rx_recycle) < sky2->rx_pending
+                            && skb_recycle_check(skb, sky2->rx_data_size
+                                                 + sky2_rx_pad(sky2->hw)))
+                                __skb_queue_head(&sky2->rx_recycle, skb);
+                        else
+                                dev_kfree_skb_any(skb);
 
-                        dev_kfree_skb_any(re->skb);
                         sky2->tx_next = RING_NEXT(idx, TX_RING_SIZE);
                 }
         }
diff --git a/drivers/net/sky2.h b/drivers/net/sky2.h
index 92fb24b27d45..b5549c9e5107 100644
--- a/drivers/net/sky2.h
+++ b/drivers/net/sky2.h
@@ -2028,6 +2028,7 @@ struct sky2_port {
         u16                  rx_pending;
         u16                  rx_data_size;
         u16                  rx_nfrags;
+        struct sk_buff_head  rx_recycle;
 
 #ifdef SKY2_VLAN_TAG_USED
         u16                  rx_tag;