[PATCH v3 bpf-next 6/9] tcp: Split out __tcp_set_rcvlowat().
flat view
COLD23d
SUPERSEDED: 2 (2M)
From: Kuniyuki Iwashima <kuniyu@google.com>
Date: 2026-10-05 15:45:47
Also in:
bpf
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
Status: Superseded by v5 (posted 2026-10-08). [go to v5]
Revision v3 (5 revisions archived); 2 review trailers.
Revisions (5)
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 <kuniyu@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
---
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 7f4ab50f08c7..adc8d1a5f926 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 a1e2bb3974ce..ce35060f82ee 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.rc1.315.gc6ed9934b7-goog