diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 821c7f4..6f2bb86 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -500,7 +500,7 @@
 	union {
 		__u32		mark;
 		__u32		dropcount;
-		__u32		avail_size;
+		__u32		reserved_tailroom;
 	};
 
 	sk_buff_data_t		inner_transport_header;
@@ -1447,7 +1447,10 @@
  */
 static inline int skb_availroom(const struct sk_buff *skb)
 {
-	return skb_is_nonlinear(skb) ? 0 : skb->avail_size - skb->len;
+	if (skb_is_nonlinear(skb))
+		return 0;
+
+	return skb->end - skb->tail - skb->reserved_tailroom;
 }
 
 /**