From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0BA44C4338F for ; Tue, 24 Aug 2021 15:30:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFEB96127B for ; Tue, 24 Aug 2021 15:30:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238344AbhHXPav (ORCPT ); Tue, 24 Aug 2021 11:30:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:41612 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237890AbhHXPat (ORCPT ); Tue, 24 Aug 2021 11:30:49 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D8AA461265; Tue, 24 Aug 2021 15:30:03 +0000 (UTC) Date: Tue, 24 Aug 2021 11:29:57 -0400 From: Steven Rostedt To: Zhongya Yan Cc: kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, edumazet@google.com, mingo@redhat.com, davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org, hengqi.chen@gmail.com, yhs@fb.com Subject: Re: [PATCH] net: tcp_drop adds `reason` parameter for tracing Message-ID: <20210824112957.3a780186@oasis.local.home> In-Reply-To: <20210824125140.190253-1-yan2228598786@gmail.com> References: <20210824125140.190253-1-yan2228598786@gmail.com> X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 24 Aug 2021 05:51:40 -0700 Zhongya Yan wrote: > When using `tcp_drop(struct sock *sk, struct sk_buff *skb)` we can > not tell why we need to delete `skb`. To solve this problem I updated the > method `tcp_drop(struct sock *sk, struct sk_buff *skb, enum tcp_drop_reason reason)` > to include the source of the deletion when it is done, so you can > get an idea of the reason for the deletion based on the source. > > The current purpose is mainly derived from the suggestions > of `Yonghong Song` and `brendangregg`: > > https://github.com/iovisor/bcc/issues/3533. > > "It is worthwhile to mention the context/why we want to this > tracepoint with bcc issue https://github.com/iovisor/bcc/issues/3533. > Mainly two reasons: (1). tcp_drop is a tiny function which > may easily get inlined, a tracepoint is more stable, and (2). > tcp_drop does not provide enough information on why it is dropped. > " by Yonghong Song > > Signed-off-by: Zhongya Yan > --- > include/net/tcp.h | 11 ++++++++ > include/trace/events/tcp.h | 56 ++++++++++++++++++++++++++++++++++++++ > net/ipv4/tcp_input.c | 34 +++++++++++++++-------- > 3 files changed, 89 insertions(+), 12 deletions(-) > > diff --git a/include/net/tcp.h b/include/net/tcp.h > index 784d5c3ef1c5..dd8cd8d6f2f1 100644 > --- a/include/net/tcp.h > +++ b/include/net/tcp.h > @@ -254,6 +254,17 @@ extern atomic_long_t tcp_memory_allocated; > extern struct percpu_counter tcp_sockets_allocated; > extern unsigned long tcp_memory_pressure; > > +enum tcp_drop_reason { > + TCP_OFO_QUEUE = 1, > + TCP_DATA_QUEUE_OFO = 2, > + TCP_DATA_QUEUE = 3, > + TCP_PRUNE_OFO_QUEUE = 4, > + TCP_VALIDATE_INCOMING = 5, > + TCP_RCV_ESTABLISHED = 6, > + TCP_RCV_SYNSENT_STATE_PROCESS = 7, > + TCP_RCV_STATE_PROCESS = 8 As enums increase by one, you could save yourself the burden of updating the numbers and just have: enum tcp_drop_reason { TCP_OFO_QUEUE = 1, TCP_DATA_QUEUE_OFO, TCP_DATA_QUEUE, TCP_PRUNE_OFO_QUEUE, TCP_VALIDATE_INCOMING, TCP_RCV_ESTABLISHED, TCP_RCV_SYNSENT_STATE_PROCESS, TCP_RCV_STATE_PROCESS }; Which would do the same. > +}; > + > /* optimized version of sk_under_memory_pressure() for TCP sockets */ > static inline bool tcp_under_memory_pressure(const struct sock *sk) > { > diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h > index 521059d8dc0a..a0d3d31eb591 100644 > --- a/include/trace/events/tcp.h > +++ b/include/trace/events/tcp.h > @@ -371,6 +371,62 @@ DEFINE_EVENT(tcp_event_skb, tcp_bad_csum, > TP_ARGS(skb) > ); > If you would like to see the english translation of what these "reasons" are and not have to remember which number is which, you can do the following: #define TCP_DROP_REASON \ EM(TCP_OFO_QUEUE, ofo_queue) \ EM(TCP_DATA_QUEUE_OFO, data_queue_ofo) \ EM(TCP_DATA_QUEUE, data_queue) \ EM(TCP_PRUNE_OFO_QUEUE, prune_ofo_queue) \ EM(TCP_VALIDATE_INCOMING, validate_incoming) \ EM(TCP_RCV_ESTABLISHED, rcv_established) \ EM(TCP_RCV_SYNSENT_STATE_PROCESS, rcv_synsent_state_process) \ EMe(TCP_RCV_STATE_PROCESS, rcv_state_proces) #undef EM #undef EMe #define EM(a,b) { a, #b }, #define EMe(a, b) { a, #b } > +TRACE_EVENT(tcp_drop, > + TP_PROTO(struct sock *sk, struct sk_buff *skb, enum tcp_drop_reason reason), > + > + TP_ARGS(sk, skb, reason), > + > + TP_STRUCT__entry( > + __array(__u8, saddr, sizeof(struct sockaddr_in6)) > + __array(__u8, daddr, sizeof(struct sockaddr_in6)) > + __field(__u16, sport) > + __field(__u16, dport) > + __field(__u32, mark) > + __field(__u16, data_len) > + __field(__u32, snd_nxt) > + __field(__u32, snd_una) > + __field(__u32, snd_cwnd) > + __field(__u32, ssthresh) > + __field(__u32, snd_wnd) > + __field(__u32, srtt) > + __field(__u32, rcv_wnd) > + __field(__u64, sock_cookie) > + __field(__u32, reason) > + ), > + > + TP_fast_assign( > + const struct tcphdr *th = (const struct tcphdr *)skb->data; > + const struct inet_sock *inet = inet_sk(sk); > + const struct tcp_sock *tp = tcp_sk(sk); > + > + memset(__entry->saddr, 0, sizeof(struct sockaddr_in6)); > + memset(__entry->daddr, 0, sizeof(struct sockaddr_in6)); > + > + TP_STORE_ADDR_PORTS(__entry, inet, sk); > + > + __entry->sport = ntohs(inet->inet_sport); > + __entry->dport = ntohs(inet->inet_dport); > + __entry->mark = skb->mark; > + > + __entry->data_len = skb->len - __tcp_hdrlen(th); > + __entry->snd_nxt = tp->snd_nxt; > + __entry->snd_una = tp->snd_una; > + __entry->snd_cwnd = tp->snd_cwnd; > + __entry->snd_wnd = tp->snd_wnd; > + __entry->rcv_wnd = tp->rcv_wnd; > + __entry->ssthresh = tcp_current_ssthresh(sk); > + __entry->srtt = tp->srtt_us >> 3; > + __entry->sock_cookie = sock_gen_cookie(sk); > + __entry->reason = reason; > + ), > + > + TP_printk("src=%pISpc dest=%pISpc mark=%#x data_len=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llx reason=%d", Then above you can have: "reason=%s" > + __entry->saddr, __entry->daddr, __entry->mark, > + __entry->data_len, __entry->snd_nxt, __entry->snd_una, > + __entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd, > + __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie, __entry->reason) And here: __print_symbolic(__entry->reason, TCP_DROP_REASON) -- Steve > +); > + > #endif /* _TRACE_TCP_H */ > > /* This part must be outside protection */ >