tcp: factorize ip_summed setting

Setting skb->ip_summed to CHECKSUM_PARTIAL can be centralized
in tcp_stream_alloc_skb() and __mptcp_do_alloc_tx_skb()
instead of being done multiple times.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

@@ -876,6 +876,7 @@ struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
 		}
 		if (likely(mem_scheduled)) {
 			skb_reserve(skb, MAX_TCP_HEADER);
+			skb->ip_summed = CHECKSUM_PARTIAL;
 			INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
 			return skb;
 		}
@@ -993,7 +994,6 @@ static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
 	skb->truesize += copy;
 	sk_wmem_queued_add(sk, copy);
 	sk_mem_charge(sk, copy);
-	skb->ip_summed = CHECKSUM_PARTIAL;
 	WRITE_ONCE(tp->write_seq, tp->write_seq + copy);
 	TCP_SKB_CB(skb)->end_seq += copy;
 	tcp_skb_pcount_set(skb, 0);
@@ -1289,7 +1289,6 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 				goto wait_for_space;
 
 			process_backlog++;
-			skb->ip_summed = CHECKSUM_PARTIAL;
 
 			tcp_skb_entail(sk, skb);
 			copy = size_goal;

net/ipv4/tcp_output.c

@@ -1590,8 +1590,6 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
 
 	skb_split(skb, buff, len);
 
-	buff->ip_summed = CHECKSUM_PARTIAL;
-
 	buff->tstamp = skb->tstamp;
 	tcp_fragment_tstamp(skb, buff);
 
@@ -1676,7 +1674,6 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
 	delta_truesize = __pskb_trim_head(skb, len);
 
 	TCP_SKB_CB(skb)->seq += len;
-	skb->ip_summed = CHECKSUM_PARTIAL;
 
 	if (delta_truesize) {
 		skb->truesize	   -= delta_truesize;
@@ -2147,7 +2144,6 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
 
 	tcp_skb_fragment_eor(skb, buff);
 
-	buff->ip_summed = CHECKSUM_PARTIAL;
 	skb_split(skb, buff, len);
 	tcp_fragment_tstamp(skb, buff);
 
@@ -2403,7 +2399,6 @@ static int tcp_mtu_probe(struct sock *sk)
 	TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK;
 	TCP_SKB_CB(nskb)->sacked = 0;
 	nskb->csum = 0;
-	nskb->ip_summed = CHECKSUM_PARTIAL;
 
 	tcp_insert_write_queue_before(nskb, skb, sk);
 	tcp_highest_sack_replace(sk, skb, nskb);
@@ -3753,7 +3748,6 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
 	syn_data = tcp_stream_alloc_skb(sk, space, sk->sk_allocation, false);
 	if (!syn_data)
 		goto fallback;
-	syn_data->ip_summed = CHECKSUM_PARTIAL;
 	memcpy(syn_data->cb, syn->cb, sizeof(syn->cb));
 	if (space) {
 		int copied = copy_from_iter(skb_put(syn_data, space), space,

net/mptcp/protocol.c

@@ -1174,6 +1174,7 @@ static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp)
 	if (likely(skb)) {
 		if (likely(__mptcp_add_ext(skb, gfp))) {
 			skb_reserve(skb, MAX_TCP_HEADER);
+			skb->ip_summed = CHECKSUM_PARTIAL;
 			INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
 			return skb;
 		}
@@ -1322,7 +1323,6 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 	skb->truesize += copy;
 	sk_wmem_queued_add(ssk, copy);
 	sk_mem_charge(ssk, copy);
-	skb->ip_summed = CHECKSUM_PARTIAL;
 	WRITE_ONCE(tcp_sk(ssk)->write_seq, tcp_sk(ssk)->write_seq + copy);
 	TCP_SKB_CB(skb)->end_seq += copy;
 	tcp_skb_pcount_set(skb, 0);