netdev - Re: [PATCH v2 net-next 2/6] net: add add indirect call wrapper in skb_release_head

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Message-ID: <a87bc4d0-9c9c-4437-a1ba-acd9fe5968b2@intel.com>
Date: Wed, 15 Oct 2025 14:02:07 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Eric Dumazet <edumazet@...gle.com>
CC: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski
	<kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman
	<horms@...nel.org>, Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang
	<xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>, Kuniyuki Iwashima
	<kuniyu@...gle.com>, Willem de Bruijn <willemb@...gle.com>,
	<netdev@...r.kernel.org>, <eric.dumazet@...il.com>
Subject: Re: [PATCH v2 net-next 2/6] net: add add indirect call wrapper in
 skb_release_head_state()

From: Eric Dumazet <edumazet@...gle.com>
Date: Tue, 14 Oct 2025 17:19:03 +0000

> While stress testing UDP senders on a host with expensive indirect
> calls, I found cpus processing TX completions where showing
> a very high cost (20%) in sock_wfree() due to
> CONFIG_MITIGATION_RETPOLINE=y.
> 
> Take care of TCP and UDP TX destructors and use INDIRECT_CALL_3() macro.
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---
>  net/core/skbuff.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index bc12790017b0..692e3a70e75e 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -1136,7 +1136,16 @@ void skb_release_head_state(struct sk_buff *skb)
>  	skb_dst_drop(skb);
>  	if (skb->destructor) {
>  		DEBUG_NET_WARN_ON_ONCE(in_hardirq());
> -		skb->destructor(skb);
> +#ifdef CONFIG_INET
> +		INDIRECT_CALL_3(skb->destructor,
> +				tcp_wfree, __sock_wfree, sock_wfree,
> +				skb);
> +#else
> +		INDIRECT_CALL_1(skb->destructor,
> +				sock_wfree,
> +				skb);
> +
> +#endif

Is it just me or seems like you ignored the suggestion/discussion under
v1 of this patch...

>  	}
>  #if IS_ENABLED(CONFIG_NF_CONNTRACK)
>  	nf_conntrack_put(skb_nfct(skb));

Thanks,
Olek