From 48040793fa6003d211f021c6ad273477bcd90d91 Mon Sep 17 00:00:00 2001
From: Yousuk Seung <ysseung@google.com>
Date: Thu, 30 Jul 2020 15:44:40 -0700
Subject: [PATCH] tcp: add earliest departure time to
SCM_TIMESTAMPING_OPT_STATS
This change adds TCP_NLA_EDT to SCM_TIMESTAMPING_OPT_STATS that reports
the earliest departure time(EDT) of the timestamped skb. By tracking EDT
values of the skb from different timestamps, we can observe when and how
much the value changed. This allows to measure the precise delay
injected on the sender host e.g. by a bpf-base throttler.
Signed-off-by: Yousuk Seung <ysseung@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/tcp.h | 3 ++-
include/uapi/linux/tcp.h | 1 +
net/core/skbuff.c | 2 +-
net/ipv4/tcp.c | 6 +++++-
4 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 527d668a52758..14b62d7df9423 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -484,7 +484,8 @@ static inline void tcp_saved_syn_free(struct tcp_sock *tp)
tp->saved_syn = NULL;
}
-struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk);
+struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
+ const struct sk_buff *orig_skb);
static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss)
{
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index f2acb25663334..cfcb10b754838 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -313,6 +313,7 @@ enum {
TCP_NLA_SRTT, /* smoothed RTT in usecs */
TCP_NLA_TIMEOUT_REHASH, /* Timeout-triggered rehash attempts */
TCP_NLA_BYTES_NOTSENT, /* Bytes in write queue not yet sent */
+ TCP_NLA_EDT, /* Earliest departure time (CLOCK_MONOTONIC) */
};
/* for TCP_MD5SIG socket option */
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index b8afefe6f6b69..4e2edfbe0e193 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4692,7 +4692,7 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
sk->sk_protocol == IPPROTO_TCP &&
sk->sk_type == SOCK_STREAM) {
- skb = tcp_get_timestamping_opt_stats(sk);
+ skb = tcp_get_timestamping_opt_stats(sk, orig_skb);
opt_stats = true;
} else
#endif
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4afec552f211b..c06d2bfd2ec46 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3501,10 +3501,12 @@ static size_t tcp_opt_stats_get_size(void)
nla_total_size(sizeof(u32)) + /* TCP_NLA_SRTT */
nla_total_size(sizeof(u16)) + /* TCP_NLA_TIMEOUT_REHASH */
nla_total_size(sizeof(u32)) + /* TCP_NLA_BYTES_NOTSENT */
+ nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_EDT */
0;
}
-struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk)
+struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
+ const struct sk_buff *orig_skb)
{
const struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *stats;
@@ -3558,6 +3560,8 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk)
nla_put_u16(stats, TCP_NLA_TIMEOUT_REHASH, tp->timeout_rehash);
nla_put_u32(stats, TCP_NLA_BYTES_NOTSENT,
max_t(int, 0, tp->write_seq - tp->snd_nxt));
+ nla_put_u64_64bit(stats, TCP_NLA_EDT, orig_skb->skb_mstamp_ns,
+ TCP_NLA_PAD);
return stats;
}
--
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