ixgbe: Make pull tail function separate from rest of cleanup_headers

This change creates a separate function for functionality similar to
pskb_pull_tail.  The main motivation for moving it to a separate function
is so that later I can just skip this function in the case where we have
already copied the buffer into skb->head.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index b0020fc..d926973 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1457,6 +1457,61 @@ static bool ixgbe_is_non_eop(struct ixgbe_ring *rx_ring,
        return true;
 }
 
+/**
+ * ixgbe_pull_tail - ixgbe specific version of skb_pull_tail
+ * @rx_ring: rx descriptor ring packet is being transacted on
+ * @skb: pointer to current skb being adjusted
+ *
+ * This function is an ixgbe specific version of __pskb_pull_tail.  The
+ * main difference between this version and the original function is that
+ * this function can make several assumptions about the state of things
+ * that allow for significant optimizations versus the standard function.
+ * As a result we can do things like drop a frag and maintain an accurate
+ * truesize for the skb.
+ */
+static void ixgbe_pull_tail(struct ixgbe_ring *rx_ring,
+                           struct sk_buff *skb)
+{
+       struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
+       unsigned char *va;
+       unsigned int pull_len;
+
+       /*
+        * it is valid to use page_address instead of kmap since we are
+        * working with pages allocated out of the lomem pool per
+        * alloc_page(GFP_ATOMIC)
+        */
+       va = skb_frag_address(frag);
+
+       /*
+        * we need the header to contain the greater of either ETH_HLEN or
+        * 60 bytes if the skb->len is less than 60 for skb_pad.
+        */
+       pull_len = skb_frag_size(frag);
+       if (pull_len > IXGBE_RX_HDR_SIZE)
+               pull_len = ixgbe_get_headlen(va, IXGBE_RX_HDR_SIZE);
+
+       /* align pull length to size of long to optimize memcpy performance */
+       skb_copy_to_linear_data(skb, va, ALIGN(pull_len, sizeof(long)));
+
+       /* update all of the pointers */
+       skb_frag_size_sub(frag, pull_len);
+       frag->page_offset += pull_len;
+       skb->data_len -= pull_len;
+       skb->tail += pull_len;
+
+       /*
+        * if we sucked the frag empty then we should free it,
+        * if there are other frags here something is screwed up in hardware
+        */
+       if (skb_frag_size(frag) == 0) {
+               BUG_ON(skb_shinfo(skb)->nr_frags != 1);
+               skb_shinfo(skb)->nr_frags = 0;
+               __skb_frag_unref(frag);
+               skb->truesize -= ixgbe_rx_bufsz(rx_ring);
+       }
+}
+
 /**
  * ixgbe_dma_sync_frag - perform DMA sync for first frag of SKB
  * @rx_ring: rx descriptor ring packet is being transacted on
@@ -1509,10 +1564,7 @@ static bool ixgbe_cleanup_headers(struct ixgbe_ring *rx_ring,
                                  union ixgbe_adv_rx_desc *rx_desc,
                                  struct sk_buff *skb)
 {
-       struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
        struct net_device *netdev = rx_ring->netdev;
-       unsigned char *va;
-       unsigned int pull_len;
 
        /* verify that the packet does not have any known errors */
        if (unlikely(ixgbe_test_staterr(rx_desc,
@@ -1522,40 +1574,8 @@ static bool ixgbe_cleanup_headers(struct ixgbe_ring *rx_ring,
                return true;
        }
 
-       /*
-        * it is valid to use page_address instead of kmap since we are
-        * working with pages allocated out of the lomem pool per
-        * alloc_page(GFP_ATOMIC)
-        */
-       va = skb_frag_address(frag);
-
-       /*
-        * we need the header to contain the greater of either ETH_HLEN or
-        * 60 bytes if the skb->len is less than 60 for skb_pad.
-        */
-       pull_len = skb_frag_size(frag);
-       if (pull_len > IXGBE_RX_HDR_SIZE)
-               pull_len = ixgbe_get_headlen(va, IXGBE_RX_HDR_SIZE);
-
-       /* align pull length to size of long to optimize memcpy performance */
-       skb_copy_to_linear_data(skb, va, ALIGN(pull_len, sizeof(long)));
-
-       /* update all of the pointers */
-       skb_frag_size_sub(frag, pull_len);
-       frag->page_offset += pull_len;
-       skb->data_len -= pull_len;
-       skb->tail += pull_len;
-
-       /*
-        * if we sucked the frag empty then we should free it,
-        * if there are other frags here something is screwed up in hardware
-        */
-       if (skb_frag_size(frag) == 0) {
-               BUG_ON(skb_shinfo(skb)->nr_frags != 1);
-               skb_shinfo(skb)->nr_frags = 0;
-               __skb_frag_unref(frag);
-               skb->truesize -= ixgbe_rx_bufsz(rx_ring);
-       }
+       /* place header in linear portion of buffer */
+       ixgbe_pull_tail(rx_ring, skb);
 
 #ifdef IXGBE_FCOE
        /* do not attempt to pad FCoE Frames as this will disrupt DDP */