[SK_BUFF]: Introduce skb_copy_from_linear_data{_offset}

To clearly state the intent of copying from linear sk_buffs, _offset being a
overly long variant but interesting for the sake of saving some bytes.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/drivers/atm/nicstar.c b/drivers/atm/nicstar.c
index 26f4b70..14ced85 100644
--- a/drivers/atm/nicstar.c
+++ b/drivers/atm/nicstar.c
@@ -2395,7 +2395,7 @@
                skb->destructor = ns_lb_destructor;
 #endif /* NS_USE_DESTRUCTORS */
                skb_push(skb, NS_SMBUFSIZE);
-               memcpy(skb->data, sb->data, NS_SMBUFSIZE);
+               skb_copy_from_linear_data(sb, skb->data, NS_SMBUFSIZE);
                skb_put(skb, len - NS_SMBUFSIZE);
                ATM_SKB(skb)->vcc = vcc;
 	       __net_timestamp(skb);
@@ -2479,7 +2479,7 @@
 	 {
             /* Copy the small buffer to the huge buffer */
             sb = (struct sk_buff *) iov->iov_base;
-            memcpy(hb->data, sb->data, iov->iov_len);
+            skb_copy_from_linear_data(sb, hb->data, iov->iov_len);
             skb_put(hb, iov->iov_len);
             remaining = len - iov->iov_len;
             iov++;
@@ -2491,7 +2491,7 @@
             {
                lb = (struct sk_buff *) iov->iov_base;
                tocopy = min_t(int, remaining, iov->iov_len);
-               memcpy(skb_tail_pointer(hb), lb->data, tocopy);
+               skb_copy_from_linear_data(lb, skb_tail_pointer(hb), tocopy);
                skb_put(hb, tocopy);
                iov++;
                remaining -= tocopy;