Subject: Re: [PATCH net-next] net: lan966x: Add support for TC flower filter statistics

From: Simon Horman <[email-masked]>
Date: Sat, 4 Feb 2023 18:12:26 +0100

On Fri, Feb 03, 2023 at 02:53:49PM +0100, Horatiu Vultur wrote:
> Add flower filter packet statistics. This will just read the TCAM
> counter of the rule, which mention how many packages were hit by this
> rule.

I am curious to know how HW stats only updating the packet count
interacts with SW stats also incrementing other values, such as the byte
count.

> Signed-off-by: Horatiu Vultur <[email-masked]>
> ---
>  .../microchip/lan966x/lan966x_tc_flower.c     | 22 +++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_tc_flower.c b/drivers/net/ethernet/microchip/lan966x/lan966x_tc_flower.c
> index 88c655d6318fa..aac3d7c87f1d5 100644
> --- a/drivers/net/ethernet/microchip/lan966x/lan966x_tc_flower.c
> +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_tc_flower.c
> @@ -234,6 +234,26 @@ static int lan966x_tc_flower_del(struct lan966x_port *port,
>  	return err;
>  }
>  
> +static int lan966x_tc_flower_stats(struct lan966x_port *port,
> +				   struct flow_cls_offload *f,
> +				   struct vcap_admin *admin)
> +{
> +	struct vcap_counter count;
> +	int err;
> +
> +	memset(&count, 0, sizeof(count));

nit: As was pointed out to me recently it's simpler to declare
     count as follows and skip the memset entirely.
     No need to respin for this!

     struct vcap_counter count = {};

> +
> +	err = vcap_get_rule_count_by_cookie(port->lan966x->vcap_ctrl,
> +					    &count, f->cookie);
> +	if (err)
> +		return err;
> +
> +	flow_stats_update(&f->stats, 0x0, count.value, 0, 0,
> +			  FLOW_ACTION_HW_STATS_IMMEDIATE);
> +
> +	return err;
> +}
> +
>  int lan966x_tc_flower(struct lan966x_port *port,
>  		      struct flow_cls_offload *f,
>  		      bool ingress)
> @@ -252,6 +272,8 @@ int lan966x_tc_flower(struct lan966x_port *port,
>  		return lan966x_tc_flower_add(port, f, admin, ingress);
>  	case FLOW_CLS_DESTROY:
>  		return lan966x_tc_flower_del(port, f, admin);
> +	case FLOW_CLS_STATS:
> +		return lan966x_tc_flower_stats(port, f, admin);
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> -- 

Also, not strictly related, but could you consider, as a favour to
reviewers, fixing the driver so that the following doesn't fail:

$ make drivers/net/ethernet/microchip/lan966x/lan966x_tc_flower.o
  DESCEND objtool
  CALL    scripts/checksyscalls.sh
  CC      drivers/net/ethernet/microchip/lan966x/lan966x_tc_flower.o
In file included from drivers/net/ethernet/microchip/lan966x/lan966x_tc_flower.c:3:
drivers/net/ethernet/microchip/lan966x/lan966x_main.h:18:10: fatal error: vcap_api.h: No such file or directory
   18 | #include <vcap_api.h>
      |          ^~~~~~~~~~~~
compilation terminated.