tcp: Introduce tcp_read_skb()

This patch inroduces tcp_read_skb() based on tcp_read_sock(),
a preparation for the next patch which actually introduces
a new sock ops.

TCP is special here, because it has tcp_read_sock() which is
mainly used by splice(). tcp_read_sock() supports partial read
and arbitrary offset, neither of them is needed for sockmap.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220615162014.89193-2-xiyou.wangcong@gmail.com

diff --git a/include/net/tcp.h b/include/net/tcp.h
index c21a9b5..7547d90 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -672,6 +672,8 @@ void tcp_get_info(struct sock *, struct tcp_info *);
 /* Read 'sendfile()'-style from a TCP socket */
 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
                  sk_read_actor_t recv_actor);
+int tcp_read_skb(struct sock *sk, read_descriptor_t *desc,
+                sk_read_actor_t recv_actor);
 
 void tcp_initialize_rcv_mss(struct sock *sk);
 

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f730945..124f384 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1734,6 +1734,53 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
 }
 EXPORT_SYMBOL(tcp_read_sock);
 
+int tcp_read_skb(struct sock *sk, read_descriptor_t *desc,
+                sk_read_actor_t recv_actor)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+       u32 seq = tp->copied_seq;
+       struct sk_buff *skb;
+       int copied = 0;
+       u32 offset;
+
+       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);
+               used = recv_actor(desc, skb, 0, skb->len);
+               if (used <= 0) {
+                       if (!copied)
+                               copied = used;
+                       break;
+               }
+               seq += used;
+               copied += used;
+
+               if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
+                       consume_skb(skb);
+                       ++seq;
+                       break;
+               }
+               consume_skb(skb);
+               if (!desc->count)
+                       break;
+               WRITE_ONCE(tp->copied_seq, seq);
+       }
+       WRITE_ONCE(tp->copied_seq, seq);
+
+       tcp_rcv_space_adjust(sk);
+
+       /* Clean up data we have read: This will do ACK frames. */
+       if (copied > 0)
+               tcp_cleanup_rbuf(sk, copied);
+
+       return copied;
+}
+EXPORT_SYMBOL(tcp_read_skb);
+
 int tcp_peek_len(struct socket *sock)
 {
        return tcp_inq(sock->sk);