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

[Toke Høiland-Jørgensen]

Adrian Moreno <amorenoz@xxxxxxxxxx> 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@xxxxxxxxxx/
> [2] https://lore.kernel.org/all/20230611105108.122586-1-gal@xxxxxxxxxx/
>
> Signed-off-by: Adrian Moreno <amorenoz@xxxxxxxxxx>
> ---
>  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