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

[Denis Kirjanov]

On 3/21/24 05:10, 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().

You should target it for net-next

> 
> 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 | 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();
>