>> From: hepeilin <he.pei...@zte.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=3d...@mail.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/20240319102549.7f7f6...@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= >-nz1x...@mail.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.pei...@zte.com.cn> >> Reviewed-by: xu xin <xu.xi...@zte.com.cn> >> Reviewed-by: Yunkai Zhang <zhang.yun...@zte.com.cn> >> Cc: Yang Yang <yang.yan...@zte.com.cn> >> Cc: Liu Chun <liu.ch...@zte.com.cn> >> Cc: Xuexin Jiang <jiang.xue...@zte.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
