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Message-ID: <CAJ+=2gi1FFe9jB8epAgm2Pqhc1PMSxmXbAR_d9Qvy3qyD4UwKg@mail.gmail.com>
Date: Thu, 8 Oct 2020 23:56:05 -0700
From: Nikita Shirokov <tehnerd@...nerd.com>
To: Yonghong Song <yhs@...com>
Cc: bpf@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Martin KaFai Lau <kafai@...com>,
netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next] bpf: add tcp_notsent_lowat bpf setsockopt
чт, 8 окт. 2020 г. в 23:27, Yonghong Song <yhs@...com>:
>
>
>
> On 10/8/20 10:08 PM, Nikita V. Shirokov wrote:
> > Adding support for TCP_NOTSENT_LOWAT sockoption
> > (https://lwn.net/Articles/560082/ ) in tcpbpf
> >
> > Signed-off-by: Nikita V. Shirokov <tehnerd@...nerd.com>
> > ---
> > include/uapi/linux/bpf.h | 2 +-
> > net/core/filter.c | 4 ++++
> > tools/testing/selftests/bpf/progs/connect4_prog.c | 15 +++++++++++++++
> > 3 files changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index d83561e8cd2c..42d2df799397 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -1698,7 +1698,7 @@ union bpf_attr {
> > * **TCP_CONGESTION**, **TCP_BPF_IW**,
> > * **TCP_BPF_SNDCWND_CLAMP**, **TCP_SAVE_SYN**,
> > * **TCP_KEEPIDLE**, **TCP_KEEPINTVL**, **TCP_KEEPCNT**,
> > - * **TCP_SYNCNT**, **TCP_USER_TIMEOUT**.
> > + * **TCP_SYNCNT**, **TCP_USER_TIMEOUT**, **TCP_NOTSENT_LOWAT**.
> > * * **IPPROTO_IP**, which supports *optname* **IP_TOS**.
> > * * **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
> > * Return
> > diff --git a/net/core/filter.c b/net/core/filter.c
> > index 05df73780dd3..5da44b11e1ec 100644
> > --- a/net/core/filter.c
> > +++ b/net/core/filter.c
> > @@ -4827,6 +4827,10 @@ static int _bpf_setsockopt(struct sock *sk, int level, int optname,
> > else
> > icsk->icsk_user_timeout = val;
> > break;
> > + case TCP_NOTSENT_LOWAT:
> > + tp->notsent_lowat = val;
> > + sk->sk_write_space(sk);
> > + break;
>
> This looks good to me. It is the same as in do_tcp_setsockopt().
>
> > default:
> > ret = -EINVAL;
> > }
> > diff --git a/tools/testing/selftests/bpf/progs/connect4_prog.c b/tools/testing/selftests/bpf/progs/connect4_prog.c
> > index b1b2773c0b9d..b10e7fbace7b 100644
> > --- a/tools/testing/selftests/bpf/progs/connect4_prog.c
> > +++ b/tools/testing/selftests/bpf/progs/connect4_prog.c
> > @@ -128,6 +128,18 @@ static __inline int set_keepalive(struct bpf_sock_addr *ctx)
> > return 0;
> > }
> >
> > +static __inline int set_notsent_lowat(struct bpf_sock_addr *ctx)
> > +{
> > + int lowat = 65535;
> > +
> > + if (ctx->type == SOCK_STREAM) {
> > + if (bpf_setsockopt(ctx, SOL_TCP, TCP_NOTSENT_LOWAT, &lowat, sizeof(lowat)))
>
> In my build system, I hit a compilation error.
>
> progs/connect4_prog.c:137:36: error: use of undeclared identifier
> 'TCP_NOTSENT_LOWAT'
> if (bpf_setsockopt(ctx, SOL_TCP, TCP_NOTSENT_LOWAT,
> &lowat, sizeof(lowat)))
>
> TCP_NOTSENT_LOWAT is included in /usr/include/linux/tcp.h. But this file
> includes netinet/tcp.h and it contains some same symbol definitions as
> linux/tcp.h so I can include both.
>
> Adding the following can fix the issue
>
> #ifndef TCP_NOTSENT_LOWAT
> #define TCP_NOTSENT_LOWAT 25
> #endif
>
> Not sure where TCP_NOTSENT_LOWAT is defined in your system.
Hey, thanks for checking. will send v2 in a few. as for my system it
is defined here:
/usr/include/netinet/tcp.h
64:#define TCP_NOTSENT_LOWAT 25 /* Limit number of unsent bytes in
>
> > + return 1;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > SEC("cgroup/connect4")
> > int connect_v4_prog(struct bpf_sock_addr *ctx)
> > {
> > @@ -148,6 +160,9 @@ int connect_v4_prog(struct bpf_sock_addr *ctx)
> > if (set_keepalive(ctx))
> > return 0;
> >
> > + if (set_notsent_lowat(ctx))
> > + return 0;
> > +
> > if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
> > return 0;
> > else if (ctx->type == SOCK_STREAM)
> >
--
Nikita
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