[PATCH 5/6] xen/netback: try to pull a minimum of 72 bytes into the skb data area

[Ian Campbell <ian.campbell@citrix.com>]

From: Steven Smith <ssmith@xensource.com>

---
 drivers/xen/netback/netback.c |    9 +++------
 1 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/netback/netback.c b/drivers/xen/netback/netback.c
index e668704..0bc6398 100644
--- a/drivers/xen/netback/netback.c
+++ b/drivers/xen/netback/netback.c
@@ -116,13 +116,10 @@ static inline int netif_page_index(struct page *pg)
 /*
  * This is the amount of packet we copy rather than map, so that the
  * guest can't fiddle with the contents of the headers while we do
- * packet processing on them (netfilter, routing, etc).  This could
- * probably do with being larger, since 1) 64-bytes isn't necessarily
- * long enough to cover a full christmas-tree ip+tcp header, let alone
- * packet contents, and 2) the data is probably in cache anyway
- * (though perhaps some other cpu's cache).
+ * packet processing on them (netfilter, routing, etc). 72 is enough
+ * to cover TCP+IP headers including options.
  */
-#define PKT_PROT_LEN 64
+#define PKT_PROT_LEN 72
 
 static struct pending_tx_info {
 	struct xen_netif_tx_request req;
-- 
1.5.6.5