[PATCH net-next v3] tcp: Add skb addr and sock addr to arguments of tracepoint tcp_probe.

From: fuyuanli
Date: Mon Mar 04 2024 - 22:04:44 EST


It is useful to expose skb addr and sock addr to user in tracepoint
tcp_probe, so that we can get more information while monitoring
receiving of tcp data, by ebpf or other ways.

For example, we need to identify a packet by seq and end_seq when
calculate transmit latency between layer 2 and layer 4 by ebpf, but which is
not available in tcp_probe, so we can only use kprobe hooking
tcp_rcv_established to get them. But we can use tcp_probe directly if skb
addr and sock addr are available, which is more efficient.

Signed-off-by: fuyuanli <fuyuanli@xxxxxxxxxxxxxx>
Reviewed-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
---
v3
Link: https://lore.kernel.org/netdev/20240304034632.GA21357@didi-ThinkCentre-M920t-N000/
1) Fix some errors of spellchecking in commit message.

v2
Link: https://lore.kernel.org/netdev/20240229052813.GA23899@didi-ThinkCentre-M920t-N000/
1) Add printing about those two addresses.
2) Target "net-next" in the title of patch.
---
include/trace/events/tcp.h | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 7b1ddffa3dfc..efb651683781 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -258,6 +258,8 @@ TRACE_EVENT(tcp_probe,
__field(__u32, srtt)
__field(__u32, rcv_wnd)
__field(__u64, sock_cookie)
+ __field(const void *, skbaddr)
+ __field(const void *, skaddr)
),

TP_fast_assign(
@@ -285,14 +287,18 @@ TRACE_EVENT(tcp_probe,
__entry->ssthresh = tcp_current_ssthresh(sk);
__entry->srtt = tp->srtt_us >> 3;
__entry->sock_cookie = sock_gen_cookie(sk);
+
+ __entry->skbaddr = skb;
+ __entry->skaddr = sk;
),

- TP_printk("family=%s src=%pISpc dest=%pISpc mark=%#x data_len=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llx",
+ TP_printk("family=%s src=%pISpc dest=%pISpc mark=%#x data_len=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llx skbaddr=%p skaddr=%p",
show_family_name(__entry->family),
__entry->saddr, __entry->daddr, __entry->mark,
__entry->data_len, __entry->snd_nxt, __entry->snd_una,
__entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd,
- __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie)
+ __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie,
+ __entry->skbaddr, __entry->skaddr)
);

#define TP_STORE_ADDR_PORTS_SKB_V4(__entry, skb) \
--
2.17.1