tipc: Increase buffer header to support worst-case device

This patch increases the headroom TIPC reserves in each sk_buff
to accommodate the largest possible link level device header.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/core.h

@@ -279,15 +279,14 @@ static inline void k_term_timer(struct timer_list *timer)
 /*
  * TIPC message buffer code
  *
- * TIPC message buffer headroom reserves space for a link-level header
- * (in case the message is sent off-node),
- * while ensuring TIPC header is word aligned for quicker access
+ * TIPC message buffer headroom reserves space for the worst-case
+ * link-level device header (in case the message is sent off-node).
  *
- * The largest header currently supported is 18 bytes, which is used when
- * the standard 14 byte Ethernet header has 4 added bytes for VLAN info
+ * Note: Headroom should be a multiple of 4 to ensure the TIPC header fields
+ *       are word aligned for quicker access
  */
 
-#define BUF_HEADROOM 20u
+#define BUF_HEADROOM LL_MAX_HEADER
 
 struct tipc_skb_cb {
 	void *handle;