From: Eric Dumazet <eric.dumazet@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Lawrence Brakmo <brakmo@fb.com>
Cc: netdev <netdev@vger.kernel.org>, Kernel Team <kernel-team@fb.com>,
Blake Matheny <bmatheny@fb.com>, Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Neal Cardwell <ncardwell@google.com>,
Yuchung Cheng <ycheng@google.com>
Subject: Re: [PATCH bpf-next v6 05/11] bpf: Adds field bpf_sock_ops_cb_flags to tcp_sock
Date: Tue, 23 Jan 2018 09:29:35 -0800 [thread overview]
Message-ID: <1516728575.3715.3.camel@gmail.com> (raw)
In-Reply-To: <20180120035220.rg55abc6gk2alere@ast-mbp>
On Fri, 2018-01-19 at 19:52 -0800, Alexei Starovoitov wrote:
> On Fri, Jan 19, 2018 at 05:45:42PM -0800, Lawrence Brakmo wrote:
> > Adds field bpf_sock_ops_cb_flags to tcp_sock and bpf_sock_ops. Its primary
> > use is to determine if there should be calls to sock_ops bpf program at
> > various points in the TCP code. The field is initialized to zero,
> > disabling the calls. A sock_ops BPF program can set it, per connection and
> > as necessary, when the connection is established.
> >
> > It also adds support for reading and writting the field within a
> > sock_ops BPF program. Reading is done by accessing the field directly.
> > However, writing is done through the helper function
> > bpf_sock_ops_cb_flags_set, in order to return an error if a BPF program
> > is trying to set a callback that is not supported in the current kernel
> > (i.e. running an older kernel). The helper function returns 0 if it was
> > able to set all of the bits set in the argument, a positive number
> > containing the bits that could not be set, or -EINVAL if the socket is
> > not a full TCP socket.
>
> ...
> > +/* Sock_ops bpf program related variables */
> > +#ifdef CONFIG_BPF
> > + u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs
> > + * values defined in uapi/linux/tcp.h
>
> I guess we can extend u8 into u16 or more if necessary in the future.
>
> > + * int bpf_sock_ops_cb_flags_set(bpf_sock_ops, flags)
> > + * Set callback flags for sock_ops
> > + * @bpf_sock_ops: pointer to bpf_sock_ops_kern struct
> > + * @flags: flags value
> > + * Return: 0 for no error
> > + * -EINVAL if there is no full tcp socket
> > + * bits in flags that are not supported by current kernel
>
> ...
> > +BPF_CALL_2(bpf_sock_ops_cb_flags_set, struct bpf_sock_ops_kern *, bpf_sock,
> > + int, argval)
> > +{
> > + struct sock *sk = bpf_sock->sk;
> > + int val = argval & BPF_SOCK_OPS_ALL_CB_FLAGS;
> > +
> > + if (!sk_fullsock(sk))
> > + return -EINVAL;
> > +
> > +#ifdef CONFIG_INET
> > + if (val)
> > + tcp_sk(sk)->bpf_sock_ops_cb_flags = val;
> > +
> > + return argval & (~BPF_SOCK_OPS_ALL_CB_FLAGS);
>
> interesting idea! took me some time to realize the potential
> of such semantics, but now I like it a lot.
> It blends 'set good flag' with 'which flags are supported' logic
> into single helper. Nice.
> Thanks for adding a test for both ways.
> Acked-by: Alexei Starovoitov <ast@kernel.org>
>
> Eric, does this approach address your concerns?
Yes, this seems fine, thanks.
next prev parent reply other threads:[~2018-01-23 17:29 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-20 1:45 [PATCH bpf-next v6 00/11] bpf: More sock_ops callbacks Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 01/11] bpf: Make SOCK_OPS_GET_TCP size independent Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 02/11] bpf: Make SOCK_OPS_GET_TCP struct independent Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 03/11] bpf: Add write access to tcp_sock and sock fields Lawrence Brakmo
2018-01-20 3:54 ` Alexei Starovoitov
2018-01-20 1:45 ` [PATCH bpf-next v6 04/11] bpf: Support passing args to sock_ops bpf function Lawrence Brakmo
2018-01-24 1:11 ` Daniel Borkmann
2018-01-24 1:30 ` Lawrence Brakmo
2018-01-24 1:34 ` Daniel Borkmann
2018-01-20 1:45 ` [PATCH bpf-next v6 05/11] bpf: Adds field bpf_sock_ops_cb_flags to tcp_sock Lawrence Brakmo
2018-01-20 3:52 ` Alexei Starovoitov
2018-01-20 7:50 ` Lawrence Brakmo
2018-01-23 17:29 ` Eric Dumazet [this message]
2018-01-20 1:45 ` [PATCH bpf-next v6 06/11] bpf: Add sock_ops RTO callback Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 07/11] bpf: Add support for reading sk_state and more Lawrence Brakmo
2018-01-24 1:05 ` Daniel Borkmann
2018-01-24 1:27 ` Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 08/11] bpf: Add sock_ops R/W access to tclass & sk_txhash Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 09/11] bpf: Add BPF_SOCK_OPS_RETRANS_CB Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 10/11] bpf: Add BPF_SOCK_OPS_STATE_CB Lawrence Brakmo
2018-01-20 1:45 ` [PATCH bpf-next v6 11/11] bpf: add selftest for tcpbpf Lawrence Brakmo
2018-01-20 3:59 ` Alexei Starovoitov
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