1 files changed, 23 insertions, 11 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 104f8444754..8814a9a52f4 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -778,6 +778,28 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 
         size = SKB_DATA_ALIGN(size);
 
+        /* Check if we can avoid taking references on fragments if we own
+         * the last reference on skb->head. (see skb_release_data())
+         */
+        if (!skb->cloned)
+                fastpath = true;
+        else {
+                int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;
+
+                fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
+        }
+
+        if (fastpath &&
+            size + sizeof(struct skb_shared_info) <= ksize(skb->head)) {
+                memmove(skb->head + size, skb_shinfo(skb),
+                        offsetof(struct skb_shared_info,
+                                 frags[skb_shinfo(skb)->nr_frags]));
+                memmove(skb->head + nhead, skb->head,
+                        skb_tail_pointer(skb) - skb->head);
+                off = nhead;
+                goto adjust_others;
+        }
+
         data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
         if (!data)
                 goto nodata;
@@ -791,17 +813,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
                skb_shinfo(skb),
                offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
 
-        /* Check if we can avoid taking references on fragments if we own
-         * the last reference on skb->head. (see skb_release_data())
-         */
-        if (!skb->cloned)
-                fastpath = true;
-        else {
-                int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;
-
-                fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
-        }
-
         if (fastpath) {
                 kfree(skb->head);
         } else {
@@ -816,6 +827,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
         off = (data + nhead) - skb->head;
 
         skb->head     = data;
+adjust_others:
         skb->data    += off;
 #ifdef NET_SKBUFF_DATA_USES_OFFSET
         skb->end      = size;