Commit 0f08335a authored by Breno Leitao's avatar Breno Leitao Committed by Jakub Kicinski
Browse files

trace: tcp: Add tracepoint for tcp_sendmsg_locked() 

Add a tracepoint to monitor TCP send operations, enabling detailed
visibility into TCP message transmission.

Create a new tracepoint within the tcp_sendmsg_locked function,
capturing traditional fields along with size_goal, which indicates the
optimal data size for a single TCP segment. Additionally, a reference to
the struct sock sk is passed, allowing direct access for BPF programs.
The implementation is largely based on David's patch[1] and suggestions.

Link: https://lore.kernel.org/all/70168c8f-bf52-4279-b4c4-be64527aa1ac@kernel.org/

 [1]
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250408-tcpsendmsg-v3-2-208b87064c28@debian.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent b1e90499

include/trace/events/tcp.h

+24 −0
Original line number Diff line number Diff line
@@ -259,6 +259,30 @@ TRACE_EVENT(tcp_retransmit_synack, 
		  __entry->saddr_v6, __entry->daddr_v6)

);



TRACE_EVENT(tcp_sendmsg_locked,

	TP_PROTO(const struct sock *sk, const struct msghdr *msg,

		 const struct sk_buff *skb, int size_goal),



	TP_ARGS(sk, msg, skb, size_goal),



	TP_STRUCT__entry(

		__field(const void *, skb_addr)

		__field(int, skb_len)

		__field(int, msg_left)

		__field(int, size_goal)

	),



	TP_fast_assign(

		__entry->skb_addr = skb;

		__entry->skb_len = skb ? skb->len : 0;

		__entry->msg_left = msg_data_left(msg);

		__entry->size_goal = size_goal;

	),



	TP_printk("skb_addr %p skb_len %d msg_left %d size_goal %d",

		  __entry->skb_addr, __entry->skb_len, __entry->msg_left,

		  __entry->size_goal));



DECLARE_TRACE(tcp_cwnd_reduction_tp,

	TP_PROTO(const struct sock *sk, int newly_acked_sacked,

		 int newly_lost, int flag),

kernel/bpf/btf.c

+1 −0
Original line number Diff line number Diff line
@@ -6541,6 +6541,7 @@ static const struct bpf_raw_tp_null_args raw_tp_null_args[] = { 
	{ "xprt_put_cong", 0x10 },

	/* tcp */

	{ "tcp_send_reset", 0x11 },

	{ "tcp_sendmsg_locked", 0x100 },

	/* tegra_apb_dma */

	{ "tegra_dma_tx_status", 0x100 },

	/* timer_migration */

net/ipv4/tcp.c

+2 −0
Original line number Diff line number Diff line
@@ -1160,6 +1160,8 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) 
		if (skb)

			copy = size_goal - skb->len;



		trace_tcp_sendmsg_locked(sk, msg, skb, size_goal);



		if (copy <= 0 || !tcp_skb_can_collapse_to(skb)) {

			bool first_skb;