On 12/2/20 9:29 PM, Prankur gupta wrote:
> Adds a new bpf_setsockopt for TCP sockets, TCP_BPF_WINDOW_CLAMP,
> which sets the maximum receiver window size. It will be useful for
> limiting receiver window based on RTT.
>
> Signed-off-by: Prankur gupta <prank...@fb.com>
> ---
> include/net/tcp.h | 1 +
> net/core/filter.c | 3 +++
> net/ipv4/tcp.c | 23 ++++++++++++++---------
> 3 files changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index 4aba0f069b05..39ced5882fe3 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -406,6 +406,7 @@ void tcp_syn_ack_timeout(const struct request_sock *req);
> int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int
> nonblock,
> int flags, int *addr_len);
> int tcp_set_rcvlowat(struct sock *sk, int val);
> +int tcp_set_window_clamp(struct sock *sk, struct tcp_sock *tp, int val);
> void tcp_data_ready(struct sock *sk);
> #ifdef CONFIG_MMU
> int tcp_mmap(struct file *file, struct socket *sock,
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 2ca5eecebacf..d6225842cfb1 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4910,6 +4910,9 @@ static int _bpf_setsockopt(struct sock *sk, int level,
> int optname,
> tp->notsent_lowat = val;
> sk->sk_write_space(sk);
> break;
> + case TCP_WINDOW_CLAMP:
> + ret = tcp_set_window_clamp(sk, tp, val);
> + break;
> default:
> ret = -EINVAL;
> }
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index b2bc3d7fe9e8..312feb8fcae5 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -3022,6 +3022,19 @@ int tcp_sock_set_keepcnt(struct sock *sk, int val)
> }
> EXPORT_SYMBOL(tcp_sock_set_keepcnt);
>
> +int tcp_set_window_clamp(struct sock *sk, struct tcp_sock *tp, int val)
No TCP function pass both sk and tp (which are identical values)
Prefer :
int tcp_set_window_clamp(struct sock *sk, int val)
{
struct tcp_sock *tp = tcp_sk(sk);
...
This will allow optimal code generation.
> +{
> + if (!val) {
> + if (sk->sk_state != TCP_CLOSE)
> + return -EINVAL;
> + tp->window_clamp = 0;
> + } else {
> + tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
> + SOCK_MIN_RCVBUF / 2 : val;
> + }
> + return 0;
> +}
> +
> /*
> * Socket option code for TCP.
> */
> @@ -3235,15 +3248,7 @@ static int do_tcp_setsockopt(struct sock *sk, int
> level, int optname,
> break;
>
> case TCP_WINDOW_CLAMP:
> - if (!val) {
> - if (sk->sk_state != TCP_CLOSE) {
> - err = -EINVAL;
> - break;
> - }
> - tp->window_clamp = 0;
> - } else
> - tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?
> - SOCK_MIN_RCVBUF / 2 : val;
> + err = tcp_set_window_clamp(sk, tp, val);
> break;
>
> case TCP_QUICKACK:
>
