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/[email protected]/ [1] Signed-off-by: Breno Leitao <[email protected]> --- include/trace/events/tcp.h | 24 ++++++++++++++++++++++++ kernel/bpf/btf.c | 1 + net/ipv4/tcp.c | 2 ++ 3 files changed, 27 insertions(+) diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h index 1a40c41ff8c30..75d3d53a3832c 100644 --- a/include/trace/events/tcp.h +++ b/include/trace/events/tcp.h @@ -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), diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index eacb701bc2be2..475a1317ad275 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6518,6 +6518,7 @@ 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 */ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index ea8de00f669d0..270ce2c8c2d54 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -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; -- 2.47.1
