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

[Vlad Buslov <vladbu@nvidia.com>]

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.