[RFC PATCH] net, gro: fix the truesize of all fragments

[Zhi Yong Wu <zwu.kernel@gmail.com>]

From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>

When the truesize of all fragments was calculated, it didn't take
the first small piece of data into account.

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
---
 net/core/skbuff.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 2b6b863..0665bd6 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3027,9 +3027,12 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 		frag->page_offset += offset;
 		skb_frag_size_sub(frag, offset);
 
-		/* all fragments truesize : remove (head size + sk_buff) */
+		/**
+		 * all fragments truesize :
+		 * remove (head size + sk_buff + offset)
+		 */
 		delta_truesize = skb->truesize -
-				 SKB_TRUESIZE(skb_end_offset(skb));
+				 SKB_TRUESIZE(skb_end_offset(skb) + offset);
 
 		skb->truesize -= skb->data_len;
 		skb->len -= skb->data_len;
@@ -3060,7 +3063,8 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 		memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 		/* We dont need to clear skbinfo->nr_frags here */
 
-		delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
+		delta_truesize = skb->truesize -
+			SKB_DATA_ALIGN(sizeof(struct sk_buff)) - offset;
 		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 		goto done;
 	}
-- 
1.7.6.5