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

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 27 Feb 2024 10:50:36 +0800 (CST)
<xu.xin16@zte.com.cn> wrote:

>  include/trace/events/icmp.h | 57 +++++++++++++++++++++++++++++++++++++++++++++
>  net/ipv4/icmp.c             |  4 ++++
>  2 files changed, 61 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..3d9af5769bc3
> --- /dev/null
> +++ b/include/trace/events/icmp.h
> @@ -0,0 +1,57 @@
> +/* 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(__u16, sport)

2 bytes

> +				__field(__u16, dport)

2 bytes

> +				__field(unsigned short, ulen)

2 bytes

[ 2 byte hole for alignment ]

> +				__field(const void *, skbaddr)

4/8 bytes

It's best to keep the holes at the end of the TP_STRUCT__entry().

That is, I would move ulen to the end of the structure. It doesn't affect
anything else.

-- Steve

> +				__field(int, type)
> +				__field(int, code)
> +				__array(__u8, saddr, 4)
> +				__array(__u8, daddr, 4)
> +		),
> +
> +		TP_fast_assign(
> +				// Get UDP header
> +				struct udphdr *uh = udp_hdr(skb);
> +				struct iphdr *iph = ip_hdr(skb);
> +				__be32 *p32;
> +
> +				__entry->sport = ntohs(uh->source);
> +				__entry->dport = ntohs(uh->dest);
> +				__entry->ulen = ntohs(uh->len);
> +				__entry->skbaddr = skb;
> +				__entry->type = type;
> +				__entry->code = code;
> +
> +				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>
> diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
> index e63a3bf99617..437bdb7e2650 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
> @@ -599,6 +601,8 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
>  	struct net *net;
>  	struct sock *sk;
> 
> +	trace_icmp_send(skb_in, type, code);
> +
>  	if (!rt)
>  		goto out;
>