net: tap: use skb_list_walk_safe helper for gso segments

This is a straight-forward conversion case for the new function, and
while we're at it, we can remove a null write to skb->next by replacing
it with skb_mark_not_on_list.
Signed-off-by: NJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tap.c

@@ -341,6 +341,7 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
 		features |= tap->tap_features;
 	if (netif_needs_gso(skb, features)) {
 		struct sk_buff *segs = __skb_gso_segment(skb, features, false);
+		struct sk_buff *next;
 
 		if (IS_ERR(segs))
 			goto drop;
@@ -352,16 +353,13 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
 		}
 
 		consume_skb(skb);
-		while (segs) {
-			struct sk_buff *nskb = segs->next;
-
-			segs->next = NULL;
-			if (ptr_ring_produce(&q->ring, segs)) {
-				kfree_skb(segs);
-				kfree_skb_list(nskb);
+		skb_list_walk_safe(segs, skb, next) {
+			skb_mark_not_on_list(skb);
+			if (ptr_ring_produce(&q->ring, skb)) {
+				kfree_skb(skb);
+				kfree_skb_list(next);
 				break;
 			}
-			segs = nskb;
 		}
 	} else {
 		/* If we receive a partial checksum and the tap side