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

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Message-ID: <CAG=2xmNBZ1V7kh7Y0425NPTLJCVyhLB82zNC6GpUN6cXJoyBMw@mail.gmail.com>
Date: Fri, 24 Oct 2025 02:05:38 -0500
From: Adrián Moreno <amorenoz@...hat.com>
To: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc: netdev@...r.kernel.org, toke@...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>, 
	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

On Thu, Oct 23, 2025 at 05:39:09PM +0200, Nicolas Dichtel wrote:
> Le 23/10/2025 à 10:34, Adrian Moreno a écrit :
> > 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 &&
> Maybe parentheses around this first condition?
>
> The size could be adjusted accordingly in if_nlmsg_size().

Good point! I'll adjust the size. Regarding the parentheses, I can wait
a bit to see if someone else weights in. I don't have a very strong
opinion about it.

Thanks.
Adrián

>
> > +	    rtnl_fill_stats(skb, dev))
> >  		goto nla_put_failure;
> >
> >  	if (rtnl_fill_vf(skb, dev, ext_filter_mask))
>