tcp: do not fake tcp headers in tcp_send_rcvq()

Now we no longer rely on having tcp headers for skbs in receive queue,
tcp repair do not need to build fake ones.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_input.c

@@ -4304,32 +4304,27 @@ static int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int
 
 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)
 {
-	struct sk_buff *skb = NULL;
-	struct tcphdr *th;
+	struct sk_buff *skb;
 	bool fragstolen;
 
 	if (size == 0)
 		return 0;
 
-	skb = alloc_skb(size + sizeof(*th), sk->sk_allocation);
+	skb = alloc_skb(size, sk->sk_allocation);
 	if (!skb)
 		goto err;
 
-	if (tcp_try_rmem_schedule(sk, skb, size + sizeof(*th)))
+	if (tcp_try_rmem_schedule(sk, skb, skb->truesize))
 		goto err_free;
 
-	th = (struct tcphdr *)skb_put(skb, sizeof(*th));
-	skb_reset_transport_header(skb);
-	memset(th, 0, sizeof(*th));
-
 	if (memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size))
 		goto err_free;
 
 	TCP_SKB_CB(skb)->seq = tcp_sk(sk)->rcv_nxt;
 	TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + size;
 	TCP_SKB_CB(skb)->ack_seq = tcp_sk(sk)->snd_una - 1;
 
-	if (tcp_queue_rcv(sk, skb, sizeof(*th), &fragstolen)) {
+	if (tcp_queue_rcv(sk, skb, 0, &fragstolen)) {
 		WARN_ON_ONCE(fragstolen); /* should not happen */
 		__kfree_skb(skb);
 	}