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

[He Peilin]

> >  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
Thank you for pointing that out. The next step is to move __field(unsigned short, ulen) to the end of TP_STRUCT__entry().

> 
> > +				__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;
> >