Re: Re: Subject: [PATCH net-next v4] net/ipv4: add tracepoint for icmp_send
From: Jason Xing
Date: Wed Apr 10 2024 - 09:23:39 EST
[...]
> >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.
I'm not against what you did (tracing all the icmp_send() for UDP) in
your original patch. I was suggesting that you could put
trace_icmp_send() in the right place, then you don't have to check the
possible error condition (like if the skb->head is valid or not, ...)
in your trace function.
One example that can avoid various checks existing in the
__icmp_send() function:
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index e63a3bf99617..2c9f7364de45 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -767,6 +767,7 @@ void __icmp_send(struct sk_buff *skb_in, int type,
int code, __be32 info,
if (!fl4.saddr)
fl4.saddr = htonl(INADDR_DUMMY);
+ trace_icmp_send(skb_in, type, code);
icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
ende:
ip_rt_put(rt);
If we go here, it means we are ready to send the ICMP skb because
we're done extracting the right information in the 'struct sk_buff
skb_in'. Simpler and easier, right?
Thanks,
Jason
>
> >> 2.Target this patch for net-next.
> >>
> >> v2->v3:
> >> Some fixes according to
> >> https://lore.kernel.org/all/20240319102549.7f7f6f53@xxxxxxxxxxxxxxxxxx/
> >> 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@xxxxxxxxxxxxxx/
> >> 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@xxxxxxxxxx>
> >> Reviewed-by: xu xin <xu.xin16@xxxxxxxxxx>
> >> Reviewed-by: Yunkai Zhang <zhang.yunkai@xxxxxxxxxx>
> >> Cc: Yang Yang <yang.yang29@xxxxxxxxxx>
> >> Cc: Liu Chun <liu.chun2@xxxxxxxxxx>
> >> Cc: Xuexin Jiang <jiang.xuexin@xxxxxxxxxx>
> >> ---
> >> 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
>
>