tcp: refactor tcp_read_skb() a bit

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>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 181a0d3501233cfb25fd34d4576a9135ebbc97f0..56a554b49caa6189a1ef178122e89eedc6409fed 100644 (file)
--- 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);