Re: [PATCH net-next 2/8] netfilter: introduce total count of hw offloaded flow table entries

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Sat, Mar 12, 2022 at 09:51:45PM +0200, Vlad Buslov wrote:
> 
> On Mon 07 Mar 2022 at 22:56, Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > On Tue, Feb 22, 2022 at 05:09:57PM +0200, Vlad Buslov wrote:
> >> To improve hardware offload debuggability and allow capping total amount of
> >> offloaded entries in following patch extend struct netns_nftables with
> >> 'count_hw' counter and expose it to userspace as 'nf_flowtable_count_hw'
> >> sysctl entry. Increment the counter together with setting NF_FLOW_HW flag
> >> when scheduling offload add task on workqueue and decrement it after
> >> successfully scheduling offload del task.
> >> 
> >> Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
> >> Signed-off-by: Oz Shlomo <ozsh@nvidia.com>
> >> Reviewed-by: Paul Blakey <paulb@nvidia.com>
> >> ---
> >>  include/net/netns/nftables.h            |  1 +
> >>  net/netfilter/nf_conntrack_standalone.c | 12 ++++++++++++
> >>  net/netfilter/nf_flow_table_core.c      | 12 ++++++++++--
> >>  3 files changed, 23 insertions(+), 2 deletions(-)
> >> 
> >> diff --git a/include/net/netns/nftables.h b/include/net/netns/nftables.h
> >> index 8c77832d0240..262b8b3213cb 100644
> >> --- a/include/net/netns/nftables.h
> >> +++ b/include/net/netns/nftables.h
> >> @@ -6,6 +6,7 @@
> >>  
> >>  struct netns_nftables {
> >>  	u8			gencursor;
> >> +	atomic_t		count_hw;
> >
> > In addition to the previous comments: I'd suggest to use
> > register_pernet_subsys() and register the sysctl from the
> > nf_flow_table_offload.c through nf_flow_table_offload_init()
> > file instead of using the conntrack nf_ct_sysctl_table[].
> >
> > That would require a bit more work though.
> 
> I added the new sysctl in ct because there is already similar-ish
> NF_SYSCTL_CT_PROTO_TIMEOUT_UDP_OFFLOAD that is also part of ct sysctl
> but is actually used by flow table code. I'll implement dedicated sysctl
> table for nf_flow_table_* code, if you suggest it is warranted for this
> change.

IIRC, that was removed.

commit 4592ee7f525c4683ec9e290381601fdee50ae110
Author: Florian Westphal <fw@strlen.de>
Date:   Wed Aug 4 15:02:15 2021 +0200

    netfilter: conntrack: remove offload_pickup sysctl again

I think it's good if we start having a dedicated sysctl for the
flowtable, yes.

Thanks.