On Mon, Mar 11, 2024 at 11:27 AM Ratheesh Kannoth <rkann...@marvell.com> wrote: > > On 2024-03-11 at 08:11:04, Jason Xing (kerneljasonx...@gmail.com) wrote: > > From: Jason Xing <kernelx...@tencent.com> > > > > Prior to this patch, what we can see by enabling trace_tcp_send is > > only happening under two circumstances: > > 1) active rst mode > > 2) non-active rst mode and based on the full socket > > > > That means the inconsistency occurs if we use tcpdump and trace > > simultaneously to see how rst happens. > > > > It's necessary that we should take into other cases into considerations, > > say: > > 1) time-wait socket > > 2) no socket > > ... > > > > By parsing the incoming skb and reversing its 4-turple can > > we know the exact 'flow' which might not exist. > > > > Samples after applied this patch: > > 1. tcp_send_reset: skbaddr=XXX skaddr=XXX src=ip:port dest=ip:port > > state=TCP_ESTABLISHED > > 2. tcp_send_reset: skbaddr=000...000 skaddr=XXX src=ip:port dest=ip:port > > state=UNKNOWN > > Note: > > 1) UNKNOWN means we cannot extract the right information from skb. > > 2) skbaddr/skaddr could be 0 > > > > Signed-off-by: Jason Xing <kernelx...@tencent.com> > > --- > > include/trace/events/tcp.h | 39 ++++++++++++++++++++++++++++++++++++-- > > net/ipv4/tcp_ipv4.c | 4 ++-- > > net/ipv6/tcp_ipv6.c | 3 ++- > > 3 files changed, 41 insertions(+), 5 deletions(-) > > > > diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h > > index 2495a1d579be..6c09d7941583 100644 > > --- a/include/trace/events/tcp.h > > +++ b/include/trace/events/tcp.h > > @@ -107,11 +107,46 @@ DEFINE_EVENT(tcp_event_sk_skb, tcp_retransmit_skb, > > * skb of trace_tcp_send_reset is the skb that caused RST. In case of > > * active reset, skb should be NULL > > */ > > -DEFINE_EVENT(tcp_event_sk_skb, tcp_send_reset, > > +TRACE_EVENT(tcp_send_reset, > > > > TP_PROTO(const struct sock *sk, const struct sk_buff *skb), > > > > - TP_ARGS(sk, skb) > > + TP_ARGS(sk, skb), > > + > > + TP_STRUCT__entry( > > + __field(const void *, skbaddr) > > + __field(const void *, skaddr) > > + __field(int, state) > > + __array(__u8, saddr, sizeof(struct sockaddr_in6)) > > + __array(__u8, daddr, sizeof(struct sockaddr_in6)) > > + ), > > + > > + TP_fast_assign( > > + __entry->skbaddr = skb; > > + __entry->skaddr = sk; > > + /* Zero means unknown state. */ > > + __entry->state = sk ? sk->sk_state : 0; > > + > > + memset(__entry->saddr, 0, sizeof(struct sockaddr_in6)); > > + memset(__entry->daddr, 0, sizeof(struct sockaddr_in6)); > > + > > + if (sk && sk_fullsock(sk)) { > > + const struct inet_sock *inet = inet_sk(sk); > > + > > + TP_STORE_ADDR_PORTS(__entry, inet, sk); > > + } else { > > + /* > > + * We should reverse the 4-turple of skb, so later > > + * it can print the right flow direction of rst. > > + */ > > + TP_STORE_ADDR_PORTS_SKB(skb, entry->daddr, > > entry->saddr); > > + } > > + ), > > + > > + TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s", > Could you consider using %px ? is it permitted ? it will be easy to track skb.
I prefer not to use %px because we cannot make use of the real address of skb. Besides, using %px would leak kernel addresses. Here is the Documentation (see Documentation/core-api/printk-formats.rst): "Pointers printed without a specifier extension (i.e unadorned %p) are hashed to give a unique identifier without leaking kernel addresses to user space." Perhaps, that's the reason why all the tracepoints didn't print in %px format:) Thanks, Jason > > > + __entry->skbaddr, __entry->skaddr, > > + __entry->saddr, __entry->daddr, > > + __entry->state ? show_tcp_state_name(__entry->state) : > > "UNKNOWN") > > ); > > > > /* > > diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c > > index a22ee5838751..d5c4a969c066 100644 > > --- a/net/ipv4/tcp_ipv4.c > > +++ b/net/ipv4/tcp_ipv4.c > > @@ -868,10 +868,10 @@ static void tcp_v4_send_reset(const struct sock *sk, > > struct sk_buff *skb) > > */ > > if (sk) { > > arg.bound_dev_if = sk->sk_bound_dev_if; > > - if (sk_fullsock(sk)) > > - trace_tcp_send_reset(sk, skb); > > } > > > > + trace_tcp_send_reset(sk, skb); > > + > > BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) != > > offsetof(struct inet_timewait_sock, tw_bound_dev_if)); > > > > diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c > > index 3f4cba49e9ee..8e9c59b6c00c 100644 > > --- a/net/ipv6/tcp_ipv6.c > > +++ b/net/ipv6/tcp_ipv6.c > > @@ -1113,7 +1113,6 @@ static void tcp_v6_send_reset(const struct sock *sk, > > struct sk_buff *skb) > > if (sk) { > > oif = sk->sk_bound_dev_if; > > if (sk_fullsock(sk)) { > > - trace_tcp_send_reset(sk, skb); > > if (inet6_test_bit(REPFLOW, sk)) > > label = ip6_flowlabel(ipv6h); > > priority = READ_ONCE(sk->sk_priority); > > @@ -1129,6 +1128,8 @@ static void tcp_v6_send_reset(const struct sock *sk, > > struct sk_buff *skb) > > label = ip6_flowlabel(ipv6h); > > } > > > > + trace_tcp_send_reset(sk, skb); > > + > > tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1, > > ipv6_get_dsfield(ipv6h), label, priority, txhash, > > &key); > > -- > > 2.37.3 > >