netdev - Re: [PATCH net-next] rtnetlink: honor RTEXT_FILTER_SKIP_STATS in IFLA

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Message-ID: <874irofkjv.fsf@toke.dk>
Date: Fri, 24 Oct 2025 16:20:36 +0200
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: Adrian Moreno <amorenoz@...hat.com>, netdev@...r.kernel.org
Cc: Adrian Moreno <amorenoz@...hat.com>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
 <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman
 <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>, Stanislav
 Fomichev <sdf@...ichev.me>, Xiao Liang <shaw.leon@...il.com>, Nicolas
 Dichtel <nicolas.dichtel@...nd.com>, Cong Wang <cong.wang@...edance.com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] rtnetlink: honor RTEXT_FILTER_SKIP_STATS in
 IFLA_STATS

Adrian Moreno <amorenoz@...hat.com> writes:

> Gathering interface statistics can be a relatively expensive operation
> on certain systems as it requires iterating over all the cpus.
>
> RTEXT_FILTER_SKIP_STATS was first introduced [1] to skip AF_INET6
> statistics from interface dumps and it was then extended [2] to
> also exclude IFLA_VF_INFO.
>
> The semantics of the flag does not seem to be limited to AF_INET
> or VF statistics and having a way to query the interface status
> (e.g: carrier, address) without retrieving its statistics seems
> reasonable. So this patch extends the use RTEXT_FILTER_SKIP_STATS
> to also affect IFLA_STATS.
>
> [1] https://lore.kernel.org/all/20150911204848.GC9687@oracle.com/
> [2] https://lore.kernel.org/all/20230611105108.122586-1-gal@nvidia.com/
>
> Signed-off-by: Adrian Moreno <amorenoz@...hat.com>
> ---
>  net/core/rtnetlink.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index 8040ff7c356e..88d52157ef1c 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -2123,7 +2123,8 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
>  	if (rtnl_phys_switch_id_fill(skb, dev))
>  		goto nla_put_failure;
>  
> -	if (rtnl_fill_stats(skb, dev))
> +	if (~ext_filter_mask & RTEXT_FILTER_SKIP_STATS &&
> +	    rtnl_fill_stats(skb, dev))

Nit: I find this:

	if (!(ext_filter_mask & RTEXT_FILTER_SKIP_STATS) &&
	    rtnl_fill_stats(skb, dev))

more readable. It's a logical operation, so the bitwise negation is less
clear IMO.

-Toke