+bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb)
+{
+ u32 limit = sk->sk_rcvbuf + sk->sk_sndbuf;
+
+ /* Only socket owner can try to collapse/prune rx queues
+ * to reduce memory overhead, so add a little headroom here.
+ * Few sockets backlog are possibly concurrently non empty.
+ */
+ limit += 64*1024;
+
+ /* In case all data was pulled from skb frags (in __pskb_pull_tail()),
+ * we can fix skb->truesize to its real value to avoid future drops.
+ * This is valid because skb is not yet charged to the socket.
+ * It has been noticed pure SACK packets were sometimes dropped
+ * (if cooked by drivers without copybreak feature).
+ */
+ if (!skb->data_len)
+ skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
+
+ if (unlikely(sk_add_backlog(sk, skb, limit))) {
+ bh_unlock_sock(sk);
+ __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPBACKLOGDROP);
+ return true;
+ }
+ return false;
+}
+EXPORT_SYMBOL(tcp_add_backlog);
+