Re: [patch net-next v4 03/10] flow_offload: check for basic action hw stats type

[Edward Cree <ecree@solarflare.com>]

On 07/03/2020 11:40, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@mellanox.com>
>
> Introduce flow_action_basic_hw_stats_types_check() helper and use it
> in drivers. That sanitizes the drivers which do not have support
> for action HW stats types.
>
> Signed-off-by: Jiri Pirko <jiri@mellanox.com>
> ---
> v3->v4:
> - fixed entries iteration in check (s/0/i/)
> - compare allowed type explicitly to 0 to avoid confusion
> v2->v3:
> - added flow_action_hw_stats_types_check() to pass allowed types
> - "mixed" bool got remove, iterate entries in check
> - added mlx5 checking instead of separate patches (will be changed by
>   later patch to flow_action_hw_stats_types_check()
> v1->v2:
> - new patch
> ---
> <snip>
> diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h
> index 93d17f37e980..8b40f612a565 100644
> --- a/include/net/flow_offload.h
> +++ b/include/net/flow_offload.h
> @@ -3,6 +3,7 @@
>  
>  #include <linux/kernel.h>
>  #include <linux/list.h>
> +#include <linux/netlink.h>
>  #include <net/flow_dissector.h>
>  #include <linux/rhashtable.h>
>  
> @@ -251,6 +252,66 @@ static inline bool flow_offload_has_one_action(const struct flow_action *action)
>  	return action->num_entries == 1;
>  }
>  
> +static inline bool
> +flow_action_mixed_hw_stats_types_check(const struct flow_action *action,
> +				       struct netlink_ext_ack *extack)
> +{
> +	const struct flow_action_entry *action_entry;
> +	u8 uninitialized_var(last_hw_stats_type);
> +	int i;
> +
> +	if (flow_offload_has_one_action(action))
> +		return true;
> +
> +	for (i = 0; i < action->num_entries; i++) {
Any reason you didn't use flow_action_for_each() here?
-ed

> +		action_entry = &action->entries[i];
> +		if (i && action_entry->hw_stats_type != last_hw_stats_type) {
> +			NL_SET_ERR_MSG_MOD(extack, "Mixing HW stats types for actions is not supported");
> +			return false;
> +		}
> +		last_hw_stats_type = action_entry->hw_stats_type;
> +	}
> +	return true;
> +}
> +
> +static inline const struct flow_action_entry *
> +flow_action_first_entry_get(const struct flow_action *action)
> +{
> +	WARN_ON(!flow_action_has_entries(action));
> +	return &action->entries[0];
> +}
> +
> +static inline bool
> +flow_action_hw_stats_types_check(const struct flow_action *action,
> +				 struct netlink_ext_ack *extack,
> +				 u8 allowed_hw_stats_type)
> +{
> +	const struct flow_action_entry *action_entry;
> +
> +	if (!flow_action_has_entries(action))
> +		return true;
> +	if (!flow_action_mixed_hw_stats_types_check(action, extack))
> +		return false;
> +	action_entry = flow_action_first_entry_get(action);
> +	if (allowed_hw_stats_type == 0 &&
> +	    action_entry->hw_stats_type != FLOW_ACTION_HW_STATS_TYPE_ANY) {
> +		NL_SET_ERR_MSG_MOD(extack, "Driver supports only default HW stats type \"any\"");
> +		return false;
> +	} else if (allowed_hw_stats_type != 0 &&
> +		   action_entry->hw_stats_type != allowed_hw_stats_type) {
> +		NL_SET_ERR_MSG_MOD(extack, "Driver does not support selected HW stats type");
> +		return false;
> +	}
> +	return true;
> +}
> +
> +static inline bool
> +flow_action_basic_hw_stats_types_check(const struct flow_action *action,
> +				       struct netlink_ext_ack *extack)
> +{
> +	return flow_action_hw_stats_types_check(action, extack, 0);
> +}
> +
>  #define flow_action_for_each(__i, __act, __actions)			\
>          for (__i = 0, __act = &(__actions)->entries[0]; __i < (__actions)->num_entries; __act = &(__actions)->entries[++__i])
>  
> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
> index 79d9b4384d7b..fca9bfa8437e 100644
> --- a/net/dsa/slave.c
> +++ b/net/dsa/slave.c
> @@ -865,6 +865,10 @@ static int dsa_slave_add_cls_matchall(struct net_device *dev,
>  	if (!flow_offload_has_one_action(&cls->rule->action))
>  		return err;
>  
> +	if (!flow_action_basic_hw_stats_types_check(&cls->rule->action,
> +						    cls->common.extack))
> +		return err;
> +
>  	act = &cls->rule->action.entries[0];
>  
>  	if (act->id == FLOW_ACTION_MIRRED && protocol == htons(ETH_P_ALL)) {