| Message ID | 20240329034243.7929-4-kerneljasonxing@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | tcp: make trace of reset logic complete | expand |
On Fri, Mar 29, 2024 at 4:43 AM Jason Xing <kerneljasonxing@gmail.com> wrote: > > From: Jason Xing <kernelxing@tencent.com> > > In addition to knowing the 4-tuple of the flow which generates RST, > the reason why it does so is very important because we have some > cases where the RST should be sent and have no clue which one > exactly. > > Adding location of reset process can help us more, like what > trace_kfree_skb does. Well, I would prefer a drop_reason here, even if there is no 'dropped' packet. This would be more stable than something based on function names that could be changed. tracepoints do not have to get ugly, we can easily get stack traces if needed. perf record -a -g -e tcp:tcp_send_reset ...
On Fri, Mar 29, 2024 at 5:13 PM Eric Dumazet <edumazet@google.com> wrote: > > On Fri, Mar 29, 2024 at 4:43 AM Jason Xing <kerneljasonxing@gmail.com> wrote: > > > > From: Jason Xing <kernelxing@tencent.com> > > > > In addition to knowing the 4-tuple of the flow which generates RST, > > the reason why it does so is very important because we have some > > cases where the RST should be sent and have no clue which one > > exactly. > > > > Adding location of reset process can help us more, like what > > trace_kfree_skb does. > > Well, I would prefer a drop_reason here, even if there is no 'dropped' packet. Good idea really. Then we can accurately diagnose which kind of reason exactly causes the RST behavior. I'm not sure if we can reuse the drop_reason here, like adding/using some reasons in enum skb_drop_reason {}? The name is a little bit strange. Oh, I can just print the string of reason directly instead of really using enum skb_drop_reason {}... > > This would be more stable than something based on function names that > could be changed. > > tracepoints do not have to get ugly, we can easily get stack traces if needed. > > perf record -a -g -e tcp:tcp_send_reset ... Ah, yes, I blindly mimic what trace_skb_kfree() and trace_consume_skb() do. Introducing some RST reasons is more reasonable and easier to detect since it's not hard to add four or five reasons only. Thanks, Jason
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h index 289438c54227..7a6dc525bfc7 100644 --- a/include/trace/events/tcp.h +++ b/include/trace/events/tcp.h @@ -80,13 +80,16 @@ DEFINE_EVENT(tcp_event_sk_skb, tcp_retransmit_skb, */ TRACE_EVENT(tcp_send_reset, - TP_PROTO(const struct sock *sk, const struct sk_buff *skb), + TP_PROTO(const struct sock *sk, + const struct sk_buff *skb, + void *location), - TP_ARGS(sk, skb), + TP_ARGS(sk, skb, location), TP_STRUCT__entry( __field(const void *, skbaddr) __field(const void *, skaddr) + __field(void *, location) __field(int, state) __array(__u8, saddr, sizeof(struct sockaddr_in6)) __array(__u8, daddr, sizeof(struct sockaddr_in6)) @@ -112,12 +115,14 @@ TRACE_EVENT(tcp_send_reset, */ TP_STORE_ADDR_PORTS_SKB(skb, entry->daddr, entry->saddr); } + __entry->location = location; ), - TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s", + TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s location=%pS", __entry->skbaddr, __entry->skaddr, __entry->saddr, __entry->daddr, - __entry->state ? show_tcp_state_name(__entry->state) : "UNKNOWN") + __entry->state ? show_tcp_state_name(__entry->state) : "UNKNOWN", + __entry->location) ); /* diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index d5c4a969c066..fec54cfc4fb3 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -870,7 +870,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) arg.bound_dev_if = sk->sk_bound_dev_if; } - trace_tcp_send_reset(sk, skb); + trace_tcp_send_reset(sk, skb, __builtin_return_address(0)); BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) != offsetof(struct inet_timewait_sock, tw_bound_dev_if)); diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index e3167ad96567..fb613582817e 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3608,7 +3608,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority) /* skb of trace_tcp_send_reset() keeps the skb that caused RST, * skb here is different to the troublesome skb, so use NULL */ - trace_tcp_send_reset(sk, NULL); + trace_tcp_send_reset(sk, NULL, __builtin_return_address(0)); } /* Send a crossed SYN-ACK during socket establishment. diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 8e9c59b6c00c..7eba9c3d69f1 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1128,7 +1128,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb) label = ip6_flowlabel(ipv6h); } - trace_tcp_send_reset(sk, skb); + trace_tcp_send_reset(sk, skb, __builtin_return_address(0)); tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1, ipv6_get_dsfield(ipv6h), label, priority, txhash,