[Patch net v3 3/4] tcp: refactor tcp_read_skb() a bit

Cong Wang
2022-08-17T19:55:33Z

As tcp_read_skb() only reads one skb at a time, the while loop is
unnecessary, we can turn it into an if. This also simplifies the
code logic.

Cc: Eric Dumazet <edumazet@google.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
---
net/ipv4/tcp.c | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 181a0d350123..56a554b49caa 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1761,25 +1761,17 @@ int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
if (sk->sk_state == TCP_LISTEN)
return -ENOTCONN;

- while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
- int used;
-
- __skb_unlink(skb, &sk->sk_receive_queue);
- WARN_ON(!skb_set_owner_sk_safe(skb, sk));
- used = recv_actor(sk, skb);
- if (used <= 0) {
- if (!copied)
- copied = used;
- break;
- }
- seq += used;
- copied += used;
+ skb = tcp_recv_skb(sk, seq, &offset);
+ if (!skb)
+ return 0;

- if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
+ __skb_unlink(skb, &sk->sk_receive_queue);
+ WARN_ON(!skb_set_owner_sk_safe(skb, sk));
+ copied = recv_actor(sk, skb);
+ if (copied > 0) {
+ seq += copied;
+ if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
++seq;
- break;
- }
- break;
}
consume_skb(skb);
WRITE_ONCE(tp->copied_seq, seq);
--
2.34.1