Re: [PATCH v3] net/ipv4: add tracepoint for icmp_send

[Jason Xing]

On Thu, Mar 21, 2024 at 10:12 AM <xu.xin16@xxxxxxxxxx> wrote:
>
> From: he peilin <he.peilin@xxxxxxxxxx>
>
>
> 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
>
>
> Changelog
>
> ---------
>
> 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=sZtRnKRu_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>

The format of the whole patch looks strange... Did you send this patch
by using 'git send-email' instead of pasting the text and sending?

>
> ---
>
>  include/trace/events/icmp.h | 64 +++++++++++++++++++++++++++++++++++++
>
>  net/ipv4/icmp.c             |  4 +++
>
>  2 files changed, 68 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..2098d4b1b12e
>
> --- /dev/null
>
> +++ b/include/trace/events/icmp.h
>
> @@ -0,0 +1,64 @@
>
> +/* 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;
>
> +
>
> + if (proto_4 == IPPROTO_UDP) {
>
> + struct udphdr *uh = udp_hdr(skb);
>
> + __entry->sport = ntohs(uh->source);
>
> + __entry->dport = ntohs(uh->dest);
>
> + __entry->ulen = ntohs(uh->len);
>
> + } else {
>
> + __entry->sport = 0;
>
> + __entry->dport = 0;
>
> + __entry->ulen = 0;
>
> + }
>
> +
>
> + 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 e63a3bf99617..21fb41257fe9 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();
>
>
>
> --
>
> 2.44.0
>
>
>
>
>