ucc_geth: Add support for skb recycling

We can reclaim transmitted skbs to use in the receive path, so-called
skb recycling support.

Also reorder ucc_geth_poll() steps, so that we'll clean tx ring firstly,
thus maybe reclaim some skbs for rx.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 30 insertions, 12 deletions

diff --git a/drivers/net/ucc_geth.c b/drivers/net/ucc_geth.c
index 5ba95867a2be..ca476a58087c 100644
--- a/drivers/net/ucc_geth.c
+++ b/drivers/net/ucc_geth.c
@@ -209,9 +209,10 @@ static struct sk_buff *get_new_skb(struct ucc_geth_private *ugeth,
 {
         struct sk_buff *skb = NULL;
 
-        skb = dev_alloc_skb(ugeth->ug_info->uf_info.max_rx_buf_length +
-                                  UCC_GETH_RX_DATA_BUF_ALIGNMENT);
-
+        skb = __skb_dequeue(&ugeth->rx_recycle);
+        if (!skb)
+                skb = dev_alloc_skb(ugeth->ug_info->uf_info.max_rx_buf_length +
+                                    UCC_GETH_RX_DATA_BUF_ALIGNMENT);
         if (skb == NULL)
                 return NULL;
 
@@ -1986,6 +1987,8 @@ static void ucc_geth_memclean(struct ucc_geth_private *ugeth)
                 iounmap(ugeth->ug_regs);
                 ugeth->ug_regs = NULL;
         }
+
+        skb_queue_purge(&ugeth->rx_recycle);
 }
 
 static void ucc_geth_set_multi(struct net_device *dev)
@@ -2202,6 +2205,8 @@ static int ucc_struct_init(struct ucc_geth_private *ugeth)
                 return -ENOMEM;
         }
 
+        skb_queue_head_init(&ugeth->rx_recycle);
+
         return 0;
 }
 
@@ -3208,8 +3213,10 @@ static int ucc_geth_rx(struct ucc_geth_private *ugeth, u8 rxQ, int rx_work_limit
                         if (netif_msg_rx_err(ugeth))
                                 ugeth_err("%s, %d: ERROR!!! skb - 0x%08x",
                                            __func__, __LINE__, (u32) skb);
-                        if (skb)
-                                dev_kfree_skb_any(skb);
+                        if (skb) {
+                                skb->data = skb->head + NET_SKB_PAD;
+                                __skb_queue_head(&ugeth->rx_recycle, skb);
+                        }
 
                         ugeth->rx_skbuff[rxQ][ugeth->skb_currx[rxQ]] = NULL;
                         dev->stats.rx_dropped++;
@@ -3267,6 +3274,8 @@ static int ucc_geth_tx(struct net_device *dev, u8 txQ)
 
         /* Normal processing. */
         while ((bd_status & T_R) == 0) {
+                struct sk_buff *skb;
+
                 /* BD contains already transmitted buffer.   */
                 /* Handle the transmitted buffer and release */
                 /* the BD to be used with the current frame  */
@@ -3276,9 +3285,16 @@ static int ucc_geth_tx(struct net_device *dev, u8 txQ)
 
                 dev->stats.tx_packets++;
 
-                /* Free the sk buffer associated with this TxBD */
-                dev_kfree_skb(ugeth->
-                                  tx_skbuff[txQ][ugeth->skb_dirtytx[txQ]]);
+                skb = ugeth->tx_skbuff[txQ][ugeth->skb_dirtytx[txQ]];
+
+                if (skb_queue_len(&ugeth->rx_recycle) < RX_BD_RING_LEN &&
+                             skb_recycle_check(skb,
+                                    ugeth->ug_info->uf_info.max_rx_buf_length +
+                                    UCC_GETH_RX_DATA_BUF_ALIGNMENT))
+                        __skb_queue_head(&ugeth->rx_recycle, skb);
+                else
+                        dev_kfree_skb(skb);
+
                 ugeth->tx_skbuff[txQ][ugeth->skb_dirtytx[txQ]] = NULL;
                 ugeth->skb_dirtytx[txQ] =
                     (ugeth->skb_dirtytx[txQ] +
@@ -3307,16 +3323,16 @@ static int ucc_geth_poll(struct napi_struct *napi, int budget)
 
         ug_info = ugeth->ug_info;
 
-        howmany = 0;
-        for (i = 0; i < ug_info->numQueuesRx; i++)
-                howmany += ucc_geth_rx(ugeth, i, budget - howmany);
-
         /* Tx event processing */
         spin_lock(&ugeth->lock);
         for (i = 0; i < ug_info->numQueuesTx; i++)
                 ucc_geth_tx(ugeth->ndev, i);
         spin_unlock(&ugeth->lock);
 
+        howmany = 0;
+        for (i = 0; i < ug_info->numQueuesRx; i++)
+                howmany += ucc_geth_rx(ugeth, i, budget - howmany);
+
         if (howmany < budget) {
                 napi_complete(napi);
                 setbits32(ugeth->uccf->p_uccm, UCCE_RX_EVENTS | UCCE_TX_EVENTS);
diff --git a/drivers/net/ucc_geth.h b/drivers/net/ucc_geth.h
index 195ab267ead7..cfb31afc08a9 100644
--- a/drivers/net/ucc_geth.h
+++ b/drivers/net/ucc_geth.h
@@ -1212,6 +1212,8 @@ struct ucc_geth_private {
         /* index of the first skb which hasn't been transmitted yet. */
         u16 skb_dirtytx[NUM_TX_QUEUES];
 
+        struct sk_buff_head rx_recycle;
+
         struct ugeth_mii_info *mii_info;
         struct phy_device *phydev;
         phy_interface_t phy_interface;