s390/qeth: simplify fragment type selection

Improve readability of the code that determines a buffer element's
fragment type, and reduce the number of cases down from 5 to 3.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core_main.c

@@ -3918,23 +3918,16 @@ static inline void __qeth_fill_buffer(struct sk_buff *skb,
 		buffer->element[element].addr = data;
 		buffer->element[element].length = length_here;
 		length -= length_here;
-		if (!length) {
-			if (first_lap)
-				if (skb_shinfo(skb)->nr_frags)
-					buffer->element[element].eflags =
-						SBAL_EFLAGS_FIRST_FRAG;
-				else
-					buffer->element[element].eflags = 0;
-			else
-				buffer->element[element].eflags =
-				    SBAL_EFLAGS_MIDDLE_FRAG;
-		} else {
-			if (first_lap)
+		if (first_lap) {
+			if (length || skb_is_nonlinear(skb))
+				/* skb needs additional elements */
 				buffer->element[element].eflags =
-				    SBAL_EFLAGS_FIRST_FRAG;
+					SBAL_EFLAGS_FIRST_FRAG;
 			else
-				buffer->element[element].eflags =
-				    SBAL_EFLAGS_MIDDLE_FRAG;
+				buffer->element[element].eflags = 0;
+		} else {
+			buffer->element[element].eflags =
+				SBAL_EFLAGS_MIDDLE_FRAG;
 		}
 		data += length_here;
 		element++;