On Mon, Apr 1, 2024 at 8:34 PM <xu.xi...@zte.com.cn> wrote: > > 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: > ============================= > 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 address, > source port, and destination port. This facilitates the trouble-shooting > of UDP packet loss issues especially for those network-service > applications. > > 2. Operation Instructions: > ========================== > Switch to the tracing directory. > cd /sys/kernel/tracing > Filter for destination port unreachable. > echo "type==3 && code==3" > events/icmp/icmp_send/filter > Enable trace event. > echo 1 > events/icmp/icmp_send/enable > > 3. Result View: > ================ > udp_client_erro-11370 [002] ...s.12 124.728002: > icmp_send: icmp_send: type=3, code=3. > From 127.0.0.1:41895 to 127.0.0.1:6666 ulen=23 > skbaddr=00000000589b167a > > v3->v4: > Some fixes according to > https://lore.kernel.org/all/CANn89i+EFEr7VHXNdOi59Ba_R1nFKSBJzBzkJFVgCTdXBx=y...@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 > 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=sztrnkru_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 = ip_hdr(skb); > + int proto_4 = iph->protocol; > + __be32 *p32; > + > + __entry->skbaddr = skb; > + __entry->type = type; > + __entry->code = code; > + > + struct udphdr *uh = udp_hdr(skb); > + if (proto_4 != IPPROTO_UDP || (u8 *)uh < skb->head || > + (u8 *)uh + sizeof(struct udphdr) > > skb_tail_pointer(skb)) { > + __entry->sport = 0; > + __entry->dport = 0; > + __entry->ulen = 0; > + } else { > + __entry->sport = ntohs(uh->source); > + __entry->dport = ntohs(uh->dest); > + __entry->ulen = ntohs(uh->len); > + } > + > + p32 = (__be32 *) __entry->saddr; > + *p32 = iph->saddr; > + > + p32 = (__be32 *) __entry->daddr; > + *p32 = iph->daddr; > + ), > + > + TP_printk("icmp_send: type=%d, code=%d. From %pI4:%u to > %pI4:%u ulen=%d skbaddr=%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, int > 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
