qeth: repair SBAL elements calculation

When sending skbs, qeth determines the number of qdio SBAL elements
required. If qeth sends a fragmented skb, the SBAL element number
calculation is wrong, because the fragmented data part is added
twice in qeth_l3_tso_elements(). This patch makes sure fragmented
data is handled in qeth_elements_for_frags() only, while
qeth_l3_tso_elements() starts calculation of qdio SBAL elements just
with the linear data part of the skb.

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_l3_main.c

@@ -2797,7 +2797,7 @@ static inline int qeth_l3_tso_elements(struct sk_buff *skb)
 {
 	unsigned long tcpd = (unsigned long)tcp_hdr(skb) +
 		tcp_hdr(skb)->doff * 4;
-	int tcpd_len = skb->len - (tcpd - (unsigned long)skb->data);
+	int tcpd_len = skb_headlen(skb) - (tcpd - (unsigned long)skb->data);
 	int elements = PFN_UP(tcpd + tcpd_len - 1) - PFN_DOWN(tcpd);
 
 	elements += qeth_get_elements_for_frags(skb);