From: Martin KaFai Lau <martin.lau@linux.dev>
To: Jason Xing <kerneljasonxing@gmail.com>
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, dsahern@kernel.org,
willemdebruijn.kernel@gmail.com, willemb@google.com,
ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev,
john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me,
haoluo@google.com, jolsa@kernel.org, shuah@kernel.org,
ykolal@fb.com, bpf@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH bpf-next v10 11/12] bpf: support selective sampling for bpf timestamping
Date: Wed, 12 Feb 2025 15:49:45 -0800 [thread overview]
Message-ID: <eb579932-e85e-4241-bfe7-6e0d780ee9d6@linux.dev> (raw)
In-Reply-To: <20250212061855.71154-12-kerneljasonxing@gmail.com>
On 2/11/25 10:18 PM, Jason Xing wrote:
> Add the bpf_sock_ops_enable_tx_tstamp kfunc to allow BPF programs to
> selectively enable TX timestamping on a skb during tcp_sendmsg().
>
> For example, BPF program will limit tracking X numbers of packets
> and then will stop there instead of tracing all the sendmsgs of
> matched flow all along. It would be helpful for users who cannot
> afford to calculate latencies from every sendmsg call probably
> due to the performance or storage space consideration.
>
> Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
> ---
> kernel/bpf/btf.c | 1 +
> net/core/filter.c | 32 +++++++++++++++++++++++++++++++-
> 2 files changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 9433b6467bbe..740210f883dc 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -8522,6 +8522,7 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
> case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
> case BPF_PROG_TYPE_CGROUP_SOCKOPT:
> case BPF_PROG_TYPE_CGROUP_SYSCTL:
> + case BPF_PROG_TYPE_SOCK_OPS:
> return BTF_KFUNC_HOOK_CGROUP;
> case BPF_PROG_TYPE_SCHED_ACT:
> return BTF_KFUNC_HOOK_SCHED_ACT;
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 7f56d0bbeb00..36793c68b125 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -12102,6 +12102,26 @@ __bpf_kfunc int bpf_sk_assign_tcp_reqsk(struct __sk_buff *s, struct sock *sk,
> #endif
> }
>
> +__bpf_kfunc int bpf_sock_ops_enable_tx_tstamp(struct bpf_sock_ops_kern *skops,
> + u64 flags)
> +{
> + struct sk_buff *skb;
> + struct sock *sk;
> +
> + if (skops->op != BPF_SOCK_OPS_TS_SND_CB)
> + return -EOPNOTSUPP;
It still needs to test the "flags" such that it can be used in the future....
if (flags)
return -EINVAL;
> +
> + skb = skops->skb;
> + sk = skops->sk;
> + skb_shinfo(skb)->tx_flags |= SKBTX_BPF;
> + if (sk_is_tcp(sk)) {
Unnecessary check like this will only confuse reader. Remove it and revisit when
UDP will be supported.
> + TCP_SKB_CB(skb)->txstamp_ack |= TSTAMP_ACK_BPF;
> + skb_shinfo(skb)->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
> + }
> +
> + return 0;
> +}
> +
> __bpf_kfunc_end_defs();
>
> int bpf_dynptr_from_skb_rdonly(struct __sk_buff *skb, u64 flags,
> @@ -12135,6 +12155,10 @@ BTF_KFUNCS_START(bpf_kfunc_check_set_tcp_reqsk)
> BTF_ID_FLAGS(func, bpf_sk_assign_tcp_reqsk, KF_TRUSTED_ARGS)
> BTF_KFUNCS_END(bpf_kfunc_check_set_tcp_reqsk)
>
> +BTF_KFUNCS_START(bpf_kfunc_check_set_sock_ops)
> +BTF_ID_FLAGS(func, bpf_sock_ops_enable_tx_tstamp, KF_TRUSTED_ARGS)
> +BTF_KFUNCS_END(bpf_kfunc_check_set_sock_ops)
> +
> static const struct btf_kfunc_id_set bpf_kfunc_set_skb = {
> .owner = THIS_MODULE,
> .set = &bpf_kfunc_check_set_skb,
> @@ -12155,6 +12179,11 @@ static const struct btf_kfunc_id_set bpf_kfunc_set_tcp_reqsk = {
> .set = &bpf_kfunc_check_set_tcp_reqsk,
> };
>
> +static const struct btf_kfunc_id_set bpf_kfunc_set_sock_ops = {
> + .owner = THIS_MODULE,
> + .set = &bpf_kfunc_check_set_sock_ops,
> +};
> +
> static int __init bpf_kfunc_init(void)
> {
> int ret;
> @@ -12173,7 +12202,8 @@ static int __init bpf_kfunc_init(void)
> ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &bpf_kfunc_set_xdp);
> ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
> &bpf_kfunc_set_sock_addr);
> - return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_kfunc_set_tcp_reqsk);
> + ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_kfunc_set_tcp_reqsk);
> + return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SOCK_OPS, &bpf_kfunc_set_sock_ops);
> }
> late_initcall(bpf_kfunc_init);
>
next prev parent reply other threads:[~2025-02-12 23:50 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-12 6:18 [PATCH bpf-next v10 00/12] net-timestamp: bpf extension to equip applications transparently Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 01/12] bpf: add networking timestamping support to bpf_get/setsockopt() Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 02/12] bpf: prepare the sock_ops ctx and call bpf prog for TX timestamping Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 03/12] bpf: prevent unsafe access to the sock fields in the BPF timestamping callback Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 04/12] bpf: disable unsafe helpers in TX timestamping callbacks Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 05/12] net-timestamp: prepare for isolating two modes of SO_TIMESTAMPING Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 06/12] bpf: add BPF_SOCK_OPS_TS_SCHED_OPT_CB callback Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 07/12] bpf: add BPF_SOCK_OPS_TS_SW_OPT_CB callback Jason Xing
2025-02-12 23:18 ` Martin KaFai Lau
2025-02-13 7:24 ` Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 08/12] bpf: add BPF_SOCK_OPS_TS_HW_OPT_CB callback Jason Xing
2025-02-12 23:20 ` Martin KaFai Lau
2025-02-13 7:24 ` Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 09/12] bpf: add BPF_SOCK_OPS_TS_ACK_OPT_CB callback Jason Xing
2025-02-12 15:26 ` Willem de Bruijn
2025-02-13 0:07 ` Jason Xing
2025-02-13 7:23 ` Jason Xing
2025-02-13 15:09 ` Willem de Bruijn
2025-02-12 6:18 ` [PATCH bpf-next v10 10/12] bpf: add BPF_SOCK_OPS_TS_SND_CB callback Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 11/12] bpf: support selective sampling for bpf timestamping Jason Xing
2025-02-12 23:49 ` Martin KaFai Lau [this message]
2025-02-13 7:26 ` Jason Xing
2025-02-12 6:18 ` [PATCH bpf-next v10 12/12] selftests/bpf: add simple bpf tests in the tx path for timestamping feature Jason Xing
2025-02-13 1:08 ` Martin KaFai Lau
2025-02-13 11:31 ` Jason Xing
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