Re: [PATCH nf-next 1/2] netfilter: flowtable: retrieve stats on flow deletion

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> Retrieve stats too when deleting a flow from hardware. Apparently, the
> existing approach is missing last stats sync with the conntrack entry.
> Pass the stats object to the driver so it has a chance to populate it
> at deletion time. Drivers need to be updated to use this new approach.
> 
> Reported-by: Valentin Berezhnoy <dreyksmail@gmail.com>
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
>  net/netfilter/nf_flow_table_offload.c | 43 ++++++++++++++++-----------
>  1 file changed, 26 insertions(+), 17 deletions(-)
> 
> diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c
> index 4365859220e6..53182323f73c 100644
> --- a/net/netfilter/nf_flow_table_offload.c
> +++ b/net/netfilter/nf_flow_table_offload.c
> @@ -934,6 +934,27 @@ static int nf_flow_offload_tuple(struct nf_flowtable *flowtable,
>  	return i;
>  }
>  
> +static void flow_offload_update_stats(struct flow_offload_work *offload,
> +				      struct flow_stats *stats)
> +{
> +	u64 lastused;
> +
> +	lastused = max_t(u64, stats[0].lastused, stats[1].lastused);
> +	offload->flow->timeout = max_t(u64, offload->flow->timeout,
> +				       lastused + flow_offload_get_timeout(offload->flow));
> +
> +	if (offload->flowtable->flags & NF_FLOWTABLE_COUNTER) {
> +		if (stats[0].pkts)
> +			nf_ct_acct_add(offload->flow->ct,
> +				       FLOW_OFFLOAD_DIR_ORIGINAL,
> +				       stats[0].pkts, stats[0].bytes);
> +		if (stats[1].pkts)
> +			nf_ct_acct_add(offload->flow->ct,
> +				       FLOW_OFFLOAD_DIR_REPLY,
> +				       stats[1].pkts, stats[1].bytes);
> +	}
> +}
> +
>  static int flow_offload_tuple_add(struct flow_offload_work *offload,
>  				  struct nf_flow_rule *flow_rule,
>  				  enum flow_offload_tuple_dir dir)
> @@ -948,10 +969,13 @@ static int flow_offload_tuple_add(struct flow_offload_work *offload,
>  static void flow_offload_tuple_del(struct flow_offload_work *offload,
>  				   enum flow_offload_tuple_dir dir)
>  {
> +	struct flow_stats stats[FLOW_OFFLOAD_DIR_MAX] = {};
> +
>  	nf_flow_offload_tuple(offload->flowtable, offload->flow, NULL, dir,
>  			      offload->flowtable->priority,
> -			      FLOW_CLS_DESTROY, NULL,
> +			      FLOW_CLS_DESTROY, stats,
>  			      &offload->flowtable->flow_block.cb_list);

according to my understanding nf_flow_offload_tuple() copies the stats just if
cmd is set to FLOW_CLS_STATS, right? Should we just check if stats is not NULL
in nf_flow_offload_tuple() instead?

Regards,
Lorenzo

> +	flow_offload_update_stats(offload, stats);
>  }
>  
>  static int flow_offload_rule_add(struct flow_offload_work *offload,
> @@ -1011,27 +1035,12 @@ static void flow_offload_tuple_stats(struct flow_offload_work *offload,
>  static void flow_offload_work_stats(struct flow_offload_work *offload)
>  {
>  	struct flow_stats stats[FLOW_OFFLOAD_DIR_MAX] = {};
> -	u64 lastused;
>  
>  	flow_offload_tuple_stats(offload, FLOW_OFFLOAD_DIR_ORIGINAL, &stats[0]);
>  	if (test_bit(NF_FLOW_HW_BIDIRECTIONAL, &offload->flow->flags))
>  		flow_offload_tuple_stats(offload, FLOW_OFFLOAD_DIR_REPLY,
>  					 &stats[1]);
> -
> -	lastused = max_t(u64, stats[0].lastused, stats[1].lastused);
> -	offload->flow->timeout = max_t(u64, offload->flow->timeout,
> -				       lastused + flow_offload_get_timeout(offload->flow));
> -
> -	if (offload->flowtable->flags & NF_FLOWTABLE_COUNTER) {
> -		if (stats[0].pkts)
> -			nf_ct_acct_add(offload->flow->ct,
> -				       FLOW_OFFLOAD_DIR_ORIGINAL,
> -				       stats[0].pkts, stats[0].bytes);
> -		if (stats[1].pkts)
> -			nf_ct_acct_add(offload->flow->ct,
> -				       FLOW_OFFLOAD_DIR_REPLY,
> -				       stats[1].pkts, stats[1].bytes);
> -	}
> +	flow_offload_update_stats(offload, stats);
>  }
>  
>  static void flow_offload_work_handler(struct work_struct *work)
> -- 
> 2.47.3
> 

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