Subject: Re: [net-next 5/9] net/mlx5e: Implement CT entry update

From: Maciej Fijalkowski <[email-masked]>
Date: Thu, 16 Feb 2023 16:51:25 +0100

On Wed, Feb 15, 2023 at 04:09:14PM -0800, Saeed Mahameed wrote:
> From: Vlad Buslov <[email-masked]>
> 
> With support for UDP NEW offload the flow_table may now send updates for
> existing flows. Support properly replacing existing entries by updating
> flow restore_cookie and replacing the rule with new one with the same match
> but new mod_hdr action that sets updated ctinfo.
> 
> Signed-off-by: Vlad Buslov <[email-masked]>
> Reviewed-by: Oz Shlomo <[email-masked]>
> Reviewed-by: Paul Blakey <[email-masked]>
> Signed-off-by: Saeed Mahameed <[email-masked]>
> ---
>  .../ethernet/mellanox/mlx5/core/en/tc_ct.c    | 118 +++++++++++++++++-
>  1 file changed, 117 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c b/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
> index 193562c14c44..76e86f83b6ac 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
> @@ -871,6 +871,68 @@ mlx5_tc_ct_entry_add_rule(struct mlx5_tc_ct_priv *ct_priv,
>  	return err;
>  }
>  
> +static int
> +mlx5_tc_ct_entry_replace_rule(struct mlx5_tc_ct_priv *ct_priv,
> +			      struct flow_rule *flow_rule,
> +			      struct mlx5_ct_entry *entry,
> +			      bool nat, u8 zone_restore_id)
> +{
> +	struct mlx5_ct_zone_rule *zone_rule = &entry->zone_rules[nat];
> +	struct mlx5_flow_attr *attr = zone_rule->attr, *old_attr;
> +	struct mlx5e_mod_hdr_handle *mh;
> +	struct mlx5_ct_fs_rule *rule;
> +	struct mlx5_flow_spec *spec;
> +	int err;
> +
> +	spec = kvzalloc(sizeof(*spec), GFP_KERNEL);
> +	if (!spec)
> +		return -ENOMEM;
> +
> +	old_attr = mlx5_alloc_flow_attr(ct_priv->ns_type);
> +	if (!attr) {

when can attr == NULL? maybe check it in the first place before allocing
spec above?

> +		err = -ENOMEM;
> +		goto err_attr;
> +	}
> +	*old_attr = *attr;
> +
> +	err = mlx5_tc_ct_entry_create_mod_hdr(ct_priv, attr, flow_rule, &mh, zone_restore_id,
> +					      nat, mlx5_tc_ct_entry_has_nat(entry));
> +	if (err) {
> +		ct_dbg("Failed to create ct entry mod hdr");
> +		goto err_mod_hdr;
> +	}
> +
> +	mlx5_tc_ct_set_tuple_match(ct_priv, spec, flow_rule);
> +	mlx5e_tc_match_to_reg_match(spec, ZONE_TO_REG, entry->tuple.zone, MLX5_CT_ZONE_MASK);
> +
> +	rule = ct_priv->fs_ops->ct_rule_add(ct_priv->fs, spec, attr, flow_rule);
> +	if (IS_ERR(rule)) {
> +		err = PTR_ERR(rule);
> +		ct_dbg("Failed to add replacement ct entry rule, nat: %d", nat);
> +		goto err_rule;
> +	}
> +
> +	ct_priv->fs_ops->ct_rule_del(ct_priv->fs, zone_rule->rule);
> +	zone_rule->rule = rule;
> +	mlx5_tc_ct_entry_destroy_mod_hdr(ct_priv, old_attr, zone_rule->mh);
> +	zone_rule->mh = mh;
> +
> +	kfree(old_attr);
> +	kvfree(spec);

not a big deal but you could make a common goto below with a different
name

> +	ct_dbg("Replaced ct entry rule in zone %d", entry->tuple.zone);
> +
> +	return 0;
> +
> +err_rule:
> +	mlx5_tc_ct_entry_destroy_mod_hdr(ct_priv, zone_rule->attr, mh);
> +	mlx5_put_label_mapping(ct_priv, attr->ct_attr.ct_labels_id);
> +err_mod_hdr:
> +	kfree(old_attr);
> +err_attr:
> +	kvfree(spec);
> +	return err;
> +}
> +
>  static bool
>  mlx5_tc_ct_entry_valid(struct mlx5_ct_entry *entry)
>  {
> @@ -1065,6 +1127,52 @@ mlx5_tc_ct_entry_add_rules(struct mlx5_tc_ct_priv *ct_priv,
>  	return err;
>  }
>  
> +static int
> +mlx5_tc_ct_entry_replace_rules(struct mlx5_tc_ct_priv *ct_priv,
> +			       struct flow_rule *flow_rule,
> +			       struct mlx5_ct_entry *entry,
> +			       u8 zone_restore_id)
> +{
> +	int err;
> +
> +	err = mlx5_tc_ct_entry_replace_rule(ct_priv, flow_rule, entry, false,

would it make sense to replace the bool nat in here with some kind of
enum?

> +					    zone_restore_id);
> +	if (err)
> +		return err;
> +
> +	err = mlx5_tc_ct_entry_replace_rule(ct_priv, flow_rule, entry, true,
> +					    zone_restore_id);
> +	if (err)
> +		mlx5_tc_ct_entry_del_rule(ct_priv, entry, false);
> +	return err;
> +}
> +
> +static int
> +mlx5_tc_ct_block_flow_offload_replace(struct mlx5_ct_ft *ft, struct flow_rule *flow_rule,
> +				      struct mlx5_ct_entry *entry, unsigned long cookie)
> +{
> +	struct mlx5_tc_ct_priv *ct_priv = ft->ct_priv;
> +	int err;
> +
> +	err = mlx5_tc_ct_entry_replace_rules(ct_priv, flow_rule, entry, ft->zone_restore_id);
> +	if (!err)
> +		return 0;
> +
> +	/* If failed to update the entry, then look it up again under ht_lock
> +	 * protection and properly delete it.
> +	 */
> +	spin_lock_bh(&ct_priv->ht_lock);
> +	entry = rhashtable_lookup_fast(&ft->ct_entries_ht, &cookie, cts_ht_params);
> +	if (entry) {
> +		rhashtable_remove_fast(&ft->ct_entries_ht, &entry->node, cts_ht_params);
> +		spin_unlock_bh(&ct_priv->ht_lock);
> +		mlx5_tc_ct_entry_put(entry);
> +	} else {
> +		spin_unlock_bh(&ct_priv->ht_lock);
> +	}
> +	return err;
> +}
> +
>  static int
>  mlx5_tc_ct_block_flow_offload_add(struct mlx5_ct_ft *ft,
>  				  struct flow_cls_offload *flow)
> @@ -1087,9 +1195,17 @@ mlx5_tc_ct_block_flow_offload_add(struct mlx5_ct_ft *ft,
>  	spin_lock_bh(&ct_priv->ht_lock);
>  	entry = rhashtable_lookup_fast(&ft->ct_entries_ht, &cookie, cts_ht_params);
>  	if (entry && refcount_inc_not_zero(&entry->refcnt)) {
> +		if (entry->restore_cookie == meta_action->ct_metadata.cookie) {
> +			spin_unlock_bh(&ct_priv->ht_lock);
> +			mlx5_tc_ct_entry_put(entry);
> +			return -EEXIST;
> +		}
> +		entry->restore_cookie = meta_action->ct_metadata.cookie;
>  		spin_unlock_bh(&ct_priv->ht_lock);
> +
> +		err = mlx5_tc_ct_block_flow_offload_replace(ft, flow_rule, entry, cookie);
>  		mlx5_tc_ct_entry_put(entry);

in case of err != 0, haven't you already put the entry inside
mlx5_tc_ct_block_flow_offload_replace() ?

> -		return -EEXIST;
> +		return err;
>  	}
>  	spin_unlock_bh(&ct_priv->ht_lock);
>  
> -- 
> 2.39.1
>