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

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Message-ID: <CANn89iL+=shdsPdkdQb=Sb1=FDn+uGsu_JXD+449=KHMabV1cQ@mail.gmail.com>
Date: Fri, 24 Oct 2025 07:35:32 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: Toke Høiland-Jørgensen <toke@...hat.com>
Cc: Adrian Moreno <amorenoz@...hat.com>, netdev@...r.kernel.org, 
	"David S. Miller" <davem@...emloft.net>, 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

On Fri, Oct 24, 2025 at 7:20 AM Toke Høiland-Jørgensen <toke@...hat.com> wrote:
>
> 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.
>

Same for me. I guess it is copy/pasted from line 1162 (in rtnl_vfinfo_size())