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Message-Id: <20240410121605.132052-1-peilinhe2020@163.com>
Date: Wed, 10 Apr 2024 12:16:05 +0000
From: Peilin He <peilinhe2020@....com>
To: kerneljasonxing@...il.com
Cc: davem@...emloft.net,
dsahern@...nel.org,
edumazet@...gle.com,
fan.yu9@....com.cn,
he.peilin@....com.cn,
jiang.xuexin@....com.cn,
kuba@...nel.org,
linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org,
liu.chun2@....com.cn,
mhiramat@...nel.org,
netdev@...r.kernel.org,
qiu.yutan@....com.cn,
rostedt@...dmis.org,
xu.xin16@....com.cn,
yang.yang29@....com.cn,
zhang.yunkai@....com.cn
Subject: Re: Re: Subject: [PATCH net-next v4] net/ipv4: add tracepoint for icmp_send
>> From: hepeilin <he.peilin@....com.cn>
>>
>> Introduce a tracepoint for icmp_send, which can help users to get more
>> detail information conveniently when icmp abnormal events happen.
>>
>> 1. Giving an usecase example:
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
>=3D=3D=3D=3D=3D
>> When an application experiences packet loss due to an unreachable UDP
>> destination port, the kernel will send an exception message through the
>> icmp_send function. By adding a trace point for icmp_send, developers or
>> system administrators can obtain detailed information about the UDP
>> packet loss, including the type, code, source address, destination addres=
>s,
>> source port, and destination port. This facilitates the trouble-shooting
>> of UDP packet loss issues especially for those network-service
>> applications.
>>
>> 2. Operation Instructions:
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
>=3D=3D
>> Switch to the tracing directory.
>> cd /sys/kernel/tracing
>> Filter for destination port unreachable.
>> echo "type=3D=3D3 && code=3D=3D3" > events/icmp/icmp_send/filter
>> Enable trace event.
>> echo 1 > events/icmp/icmp_send/enable
>>
>> 3. Result View:
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> udp_client_erro-11370 [002] ...s.12 124.728002:
>> icmp_send: icmp_send: type=3D3, code=3D3.
>> From 127.0.0.1:41895 to 127.0.0.1:6666 ulen=3D23
>> skbaddr=3D00000000589b167a
>>
>> v3->v4:
>> Some fixes according to
>> https://lore.kernel.org/all/CANn89i+EFEr7VHXNdOi59Ba_R1nFKSBJzBzkJFVgCTdX=
>Bx=3DYBg@...l.gmail.com/
>> 1.Add legality check for UDP header in SKB.
>
>I think my understanding based on what Eric depicted differs from you:
>we're supposed to filter out those many invalid cases and only trace
>the valid action of sending a icmp, so where to add a new tracepoint
>is important instead of adding more checks in the tracepoint itself.
>Please refer to what trace_tcp_retransmit_skb() does :)
>
>Thanks,
>Jason
Okay, thank you for your suggestion. In order to avoid filtering out
those many invalid cases and only tracing the valid action of sending
a icmp, the next patch will add udd_fail_no_port trancepoint to the
include/trace/events/udp.h. This will solve the problem you mentioned
very well. At this point, only UDP protocol exceptions will be tracked,
without the need to track them in icmp_send.
>> 2.Target this patch for net-next.
>>
>> v2->v3:
>> Some fixes according to
>> https://lore.kernel.org/all/20240319102549.7f7f6f53@gandalf.local.home/
>> 1. Change the tracking directory to/sys/kernel/tracking.
>> 2. Adjust the layout of the TP-STRUCT_entry parameter structure.
>>
>> v1->v2:
>> Some fixes according to
>> https://lore.kernel.org/all/CANn89iL-y9e_VFpdw=3DsZtRnKRu_tnUwqHuFQTJvJsv=
>-nz1xPDw@...l.gmail.com/
>> 1. adjust the trace_icmp_send() to more protocols than UDP.
>> 2. move the calling of trace_icmp_send after sanity checks
>> in __icmp_send().
>>
>> Signed-off-by: Peilin He<he.peilin@....com.cn>
>> Reviewed-by: xu xin <xu.xin16@....com.cn>
>> Reviewed-by: Yunkai Zhang <zhang.yunkai@....com.cn>
>> Cc: Yang Yang <yang.yang29@....com.cn>
>> Cc: Liu Chun <liu.chun2@....com.cn>
>> Cc: Xuexin Jiang <jiang.xuexin@....com.cn>
>> ---
>> include/trace/events/icmp.h | 65 +++++++++++++++++++++++++++++++++++++
>> net/ipv4/icmp.c | 4 +++
>> 2 files changed, 69 insertions(+)
>> create mode 100644 include/trace/events/icmp.h
>>
>> diff --git a/include/trace/events/icmp.h b/include/trace/events/icmp.h
>> new file mode 100644
>> index 000000000000..7d5190f48a28
>> --- /dev/null
>> +++ b/include/trace/events/icmp.h
>> @@ -0,0 +1,65 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +#undef TRACE_SYSTEM
>> +#define TRACE_SYSTEM icmp
>> +
>> +#if !defined(_TRACE_ICMP_H) || defined(TRACE_HEADER_MULTI_READ)
>> +#define _TRACE_ICMP_H
>> +
>> +#include <linux/icmp.h>
>> +#include <linux/tracepoint.h>
>> +
>> +TRACE_EVENT(icmp_send,
>> +
>> + TP_PROTO(const struct sk_buff *skb, int type, int code),
>> +
>> + TP_ARGS(skb, type, code),
>> +
>> + TP_STRUCT__entry(
>> + __field(const void *, skbaddr)
>> + __field(int, type)
>> + __field(int, code)
>> + __array(__u8, saddr, 4)
>> + __array(__u8, daddr, 4)
>> + __field(__u16, sport)
>> + __field(__u16, dport)
>> + __field(unsigned short, ulen)
>> + ),
>> +
>> + TP_fast_assign(
>> + struct iphdr *iph =3D ip_hdr(skb);
>> + int proto_4 =3D iph->protocol;
>> + __be32 *p32;
>> +
>> + __entry->skbaddr =3D skb;
>> + __entry->type =3D type;
>> + __entry->code =3D code;
>> +
>> + struct udphdr *uh =3D udp_hdr(skb);
>> + if (proto_4 !=3D IPPROTO_UDP || (u8 *)uh < skb->h=
>ead ||
>> + (u8 *)uh + sizeof(struct udphdr) > skb_ta=
>il_pointer(skb)) {
>> + __entry->sport =3D 0;
>> + __entry->dport =3D 0;
>> + __entry->ulen =3D 0;
>> + } else {
>> + __entry->sport =3D ntohs(uh->source);
>> + __entry->dport =3D ntohs(uh->dest);
>> + __entry->ulen =3D ntohs(uh->len);
>> + }
>> +
>> + p32 =3D (__be32 *) __entry->saddr;
>> + *p32 =3D iph->saddr;
>> +
>> + p32 =3D (__be32 *) __entry->daddr;
>> + *p32 =3D iph->daddr;
>> + ),
>> +
>> + TP_printk("icmp_send: type=3D%d, code=3D%d. From %pI4:%u =
>to %pI4:%u ulen=3D%d skbaddr=3D%p",
>> + __entry->type, __entry->code,
>> + __entry->saddr, __entry->sport, __entry->daddr,
>> + __entry->dport, __entry->ulen, __entry->skbaddr)
>> +);
>> +
>> +#endif /* _TRACE_ICMP_H */
>> +
>> +/* This part must be outside protection */
>> +#include <trace/define_trace.h>
>> \ No newline at end of file
>> diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
>> index 8cebb476b3ab..224551d75c02 100644
>> --- a/net/ipv4/icmp.c
>> +++ b/net/ipv4/icmp.c
>> @@ -92,6 +92,8 @@
>> #include <net/inet_common.h>
>> #include <net/ip_fib.h>
>> #include <net/l3mdev.h>
>> +#define CREATE_TRACE_POINTS
>> +#include <trace/events/icmp.h>
>>
>> /*
>> * Build xmit assembly blocks
>> @@ -672,6 +674,8 @@ void __icmp_send(struct sk_buff *skb_in, int type, in=
>t code, __be32 info,
>> }
>> }
>>
>> + trace_icmp_send(skb_in, type, code);
>> +
>> /* Needed by both icmp_global_allow and icmp_xmit_lock */
>> local_bh_disable();
>>
>> --
>> 2.25.1
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