Re: [PATCH] udp6: add a missing call into udp_fail_queue_rcv_skb tracepoint

[Paolo Abeni <pabeni@redhat.com>]

Hi,

On Thu, 2023-07-06 at 10:22 -0700, Ivan Babrou wrote:
> The tracepoint has existed for 12 years, but it only covered udp
> over the legacy IPv4 protocol. Having it enabled for udp6 removes
> the unnecessary difference in error visibility.
> 
> Signed-off-by: Ivan Babrou <ivan@cloudflare.com>
> Fixes: 296f7ea75b45 ("udp: add tracepoints for queueing skb to rcvbuf")
> ---
>  net/ipv6/udp.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index e5a337e6b970..debb98fb23c0 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -45,6 +45,7 @@
>  #include <net/tcp_states.h>
>  #include <net/ip6_checksum.h>
>  #include <net/ip6_tunnel.h>
> +#include <trace/events/udp.h>
>  #include <net/xfrm.h>
>  #include <net/inet_hashtables.h>
>  #include <net/inet6_hashtables.h>
> @@ -680,6 +681,7 @@ static int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
>  		}
>  		UDP6_INC_STATS(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
>  		kfree_skb_reason(skb, drop_reason);
> +		trace_udp_fail_queue_rcv_skb(rc, sk);
>  		return -1;
>  	}

The patch looks correct and consistency is a nice thing, but I'm
wondering if we should instead remove the tracepoint from the UDP v4
code? We already have drop reason and MIBs to pin-point quite
accurately UDP drops, and the trace point does not cover a few UDPv4
spots (e.g. mcast). WDYT?

Thanks!

Paolo