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

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Message-ID: <475d1b3a-53d2-4778-ab56-0df25847c50a@6wind.com>
Date: Fri, 24 Oct 2025 09:17:38 +0200
From: Nicolas Dichtel <nicolas.dichtel@...nd.com>
To: Adrián Moreno <amorenoz@...hat.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

Le 24/10/2025 à 09:05, Adrián Moreno a écrit :
> 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.
No pb on my side. I was asking myself what the preference is on netdev :)

Thansk,
Nicolas