We will add a kfunc for bpf_tcp_ops.{enqueue,dequeue}_rcvq() to adjust sk->sk_rcvlowat. These hooks are triggered * when the TCP stack enqueues an skb to sk->sk_receive_queue * after data is dequeued from sk->sk_receive_queue In the enqueue path, tcp_data_ready() is always called after the hooks in tcp_queue_rcv() and tcp_ofo_queue(). If tcp_set_rcvlowat() were used as is, tcp_data_ready() could be called twice for the same skb, which is redundant and also confusing. Let's split out __tcp_set_rcvlowat() and add a flag to control wakeup behaviour. Signed-off-by: Kuniyuki Iwashima Acked-by: Stanislav Fomichev Reviewed-by: Emil Tsalapatis Reviewed-by: Amery Hung --- include/net/tcp.h | 1 + net/ipv4/tcp.c | 12 +++++++++--- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index d95cbe4da96e..f7624ab9b420 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -512,6 +512,7 @@ void tcp_set_keepalive(struct sock *sk, int val); void tcp_syn_ack_timeout(const struct request_sock *req); int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags); +int __tcp_set_rcvlowat(struct sock *sk, int val, bool wakeup); int tcp_set_rcvlowat(struct sock *sk, int val); void tcp_set_rcvbuf(struct sock *sk, int val); int tcp_set_window_clamp(struct sock *sk, int val); diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 5d907a0a0461..c3c756a1ba8c 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1827,8 +1827,7 @@ int tcp_peek_len(struct socket *sock) return tcp_inq(sock->sk); } -/* Make sure sk_rcvbuf is big enough to satisfy SO_RCVLOWAT hint */ -int tcp_set_rcvlowat(struct sock *sk, int val) +int __tcp_set_rcvlowat(struct sock *sk, int val, bool wakeup) { struct tcp_sock *tp = tcp_sk(sk); int space, cap; @@ -1841,7 +1840,8 @@ int tcp_set_rcvlowat(struct sock *sk, int val) WRITE_ONCE(sk->sk_rcvlowat, val ? : 1); /* Check if we need to signal EPOLLIN right now */ - tcp_data_ready(sk); + if (wakeup) + tcp_data_ready(sk); if (sk->sk_userlocks & SOCK_RCVBUF_LOCK) return 0; @@ -1856,6 +1856,12 @@ int tcp_set_rcvlowat(struct sock *sk, int val) return 0; } +/* Make sure sk_rcvbuf is big enough to satisfy SO_RCVLOWAT hint */ +int tcp_set_rcvlowat(struct sock *sk, int val) +{ + return __tcp_set_rcvlowat(sk, val, true); +} + void tcp_set_rcvbuf(struct sock *sk, int val) { tcp_set_window_clamp(sk, tcp_win_from_space(sk, val)); -- 2.56.0.360.g66cac248cb-goog