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

[Vlad Buslov <vladbu@nvidia.com>]

On Tue 15 Mar 2022 at 11:41, Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> 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.

Got it. Will move these sysctls into dedicated namespace in v2.