From: Breno Leitao <[email protected]> Date: Mon, 07 Apr 2025 06:40:44 -0700 > 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 and suggestions. > > The implementation is largely based on David's patch[1] and suggestions.
nit: duplicate sentences. > > Link: > https://lore.kernel.org/all/[email protected]/ > [1] > Signed-off-by: Breno Leitao <[email protected]> > --- > include/trace/events/tcp.h | 24 ++++++++++++++++++++++++ > net/ipv4/tcp.c | 2 ++ > 2 files changed, 26 insertions(+) > > diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h > index 1a40c41ff8c30..cab25504c4f9d 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/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); skb could be NULL, so I think raw_tp_null_args[] needs to be updated. Maybe try attaching a bpf prog that dereferences skb unconditionally and see if the bpf verifier rejects it. See this commit for the similar issue: commit 5da7e15fb5a12e78de974d8908f348e279922ce9 Author: Kuniyuki Iwashima <[email protected]> Date: Fri Jan 31 19:01:42 2025 -0800 net: Add rx_skb of kfree_skb to raw_tp_null_args[]. > + > if (copy <= 0 || !tcp_skb_can_collapse_to(skb)) { > bool first_skb; > > > -- > 2.47.1
