- /* Copy the skb if there is no space for the header. */
- if (headroom < (sizeof(struct pppoe_hdr) + dev->hard_header_len)) {
- skb2 = dev_alloc_skb(32+skb->len +
- sizeof(struct pppoe_hdr) +
- dev->hard_header_len);
-
- if (skb2 == NULL)
- goto abort;
-
- skb_reserve(skb2, dev->hard_header_len + sizeof(struct pppoe_hdr));
- skb_copy_from_linear_data(skb, skb_put(skb2, skb->len),
- skb->len);
- } else {
- /* Make a clone so as to not disturb the original skb,
- * give dev_queue_xmit something it can free.
- */
- skb2 = skb_clone(skb, GFP_ATOMIC);
-
- if (skb2 == NULL)
- goto abort;
- }
-
- ph = (struct pppoe_hdr *) skb_push(skb2, sizeof(struct pppoe_hdr));
- memcpy(ph, &hdr, sizeof(struct pppoe_hdr));
- skb2->protocol = __constant_htons(ETH_P_PPP_SES);
+ /* Copy the data if there is no space for the header or if it's
+ * read-only.
+ */
+ if (skb_cow_head(skb, sizeof(*ph) + dev->hard_header_len))
+ goto abort;