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

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Message-ID: <43916b1a-e6bb-407d-852c-eaa3c4652d03@6wind.com>
Date: Fri, 24 Oct 2025 16:59:26 +0200
From: Nicolas Dichtel <nicolas.dichtel@...nd.com>
To: Eric Dumazet <edumazet@...gle.com>,
 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>, 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



Le 24/10/2025 à 16:35, Eric Dumazet a écrit :
> 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())
I agree. I didn't point it out because there are several occurrences in this
file (line 1599 / rtnl_fill_vfinfo()).