[PATCH net-next 0/2] net/mlx5: less memory per offloaded tc rule

[PATCH net-next 0/2] net/mlx5: less memory per offloaded tc rule

[Alexandre Cassen]

Two mlx5 allocations hold more memory than an offloaded tc rule needs.
A NIC flow keeps a 4 KB allocation for parse attributes that nothing
reads after offload. An FTE under hardware steering keeps the 1 KB
action array it was built in while a rule rarely needs more than three
entries.

Freeing the first after offload saves 4 KB per NIC flow. Shrinking the
second saves about 1 KB per FTE under hardware steering.

Alexandre Cassen (2):
  net/mlx5e: TC, free NIC flow parse attributes after offload
  net/mlx5: HWS, shrink FTE action array to fit

 .../net/ethernet/mellanox/mlx5/core/en_tc.c    | 18 +++++++++++++-----
 .../mellanox/mlx5/core/steering/hws/fs_hws.c   | 10 +++++++++-
 2 files changed, 22 insertions(+), 6 deletions(-)

-- 
2.43.0

[PATCH net-next 1/2] net/mlx5e: TC, free NIC flow parse attributes after offload

[Alexandre Cassen]

A NIC flow holds a 4 KB allocation for its parse attributes until
deletion although nothing reads them after offload. Free them once the
rule is in.

Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>
---
 .../net/ethernet/mellanox/mlx5/core/en_tc.c    | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index c99e824b4c6d..708b7987ea4c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -1414,6 +1414,16 @@ void mlx5e_del_offloaded_nic_rule(struct mlx5e_priv *priv,
 				      MLX5E_TC_FT_LEVEL);
 }
 
+static void mlx5e_tc_free_parse_attr(struct mlx5_flow_attr *attr)
+{
+	if (!attr->parse_attr)
+		return;
+
+	mlx5e_mod_hdr_dealloc(&attr->parse_attr->mod_hdr_acts);
+	kvfree(attr->parse_attr);
+	attr->parse_attr = NULL;
+}
+
 static void mlx5e_tc_del_nic_flow(struct mlx5e_priv *priv,
 				  struct mlx5e_tc_flow *flow)
 {
@@ -1436,10 +1446,8 @@ static void mlx5e_tc_del_nic_flow(struct mlx5e_priv *priv,
 	}
 	mutex_unlock(&tc->t_lock);
 
-	if (attr->action & MLX5_FLOW_CONTEXT_ACTION_MOD_HDR) {
-		mlx5e_mod_hdr_dealloc(&attr->parse_attr->mod_hdr_acts);
+	if (attr->action & MLX5_FLOW_CONTEXT_ACTION_MOD_HDR)
 		mlx5e_tc_detach_mod_hdr(priv, flow, attr);
-	}
 
 	if (attr->action & MLX5_FLOW_CONTEXT_ACTION_COUNT)
 		mlx5_fc_destroy(priv->mdev, attr->counter);
@@ -1450,7 +1458,7 @@ static void mlx5e_tc_del_nic_flow(struct mlx5e_priv *priv,
 	free_flow_post_acts(flow);
 	mlx5_tc_ct_delete_flow(get_ct_priv(flow->priv), attr);
 
-	kvfree(attr->parse_attr);
+	mlx5e_tc_free_parse_attr(attr);
 	kfree(flow->attr);
 }
 
@@ -4759,6 +4767,7 @@ mlx5e_add_nic_flow(struct mlx5e_priv *priv,
 	if (err)
 		goto err_free;
 
+	mlx5e_tc_free_parse_attr(flow->attr);
 	flow_flag_set(flow, OFFLOADED);
 	*__flow = flow;
 
@@ -4766,7 +4775,6 @@ mlx5e_add_nic_flow(struct mlx5e_priv *priv,
 
 err_free:
 	flow_flag_set(flow, FAILED);
-	mlx5e_mod_hdr_dealloc(&parse_attr->mod_hdr_acts);
 	mlx5e_flow_put(priv, flow);
 out:
 	return err;
-- 
2.43.0

Re: [PATCH net-next 1/2] net/mlx5e: TC, free NIC flow parse attributes after offload

[sashiko-bot]

> A NIC flow holds a 4 KB allocation for its parse attributes until
> deletion although nothing reads them after offload. Free them once the
> rule is in.
> 
> Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261009052103.3621855-1-acassen@corp.free.fr?part=1

Re: [PATCH net-next 1/2] net/mlx5e: TC, free NIC flow parse attributes after offload

[Simon Horman]

On Fri, Oct 09, 2026 at 07:21:00AM +0200, Alexandre Cassen wrote:
> A NIC flow holds a 4 KB allocation for its parse attributes until
> deletion although nothing reads them after offload. Free them once the
> rule is in.
> 
> Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>

Reviewed-by: Simon Horman <horms@kernel.org>

[PATCH net-next 2/2] net/mlx5: HWS, shrink FTE action array to fit

[Alexandre Cassen]

An FTE keeps the actions it must release in the array used to build
them. This is a 1 KB allocation sized for MLX5_FLOW_CONTEXT_ACTION_MAX
entries while a rule rarely needs more than three. Keep a copy sized to
the actions in use.

Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>
---
 .../ethernet/mellanox/mlx5/core/steering/hws/fs_hws.c  | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws.c
index 5a172c572a68..da6e57c103d6 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws.c
@@ -746,6 +746,7 @@ static int mlx5_fs_fte_get_hws_actions(struct mlx5_flow_root_namespace *ns,
 	struct mlx5_fs_hws_context *fs_ctx = &ns->fs_hws_context;
 	struct mlx5hws_action_dest_attr *dest_actions;
 	struct mlx5hws_context *ctx = fs_ctx->hws_ctx;
+	struct mlx5_fs_hws_rule_action *rule_actions;
 	struct mlx5_fs_hws_rule_action *fs_actions;
 	struct mlx5_core_dev *dev = ns->dev;
 	struct mlx5hws_action *dest_action;
@@ -1041,13 +1042,20 @@ static int mlx5_fs_fte_get_hws_actions(struct mlx5_flow_root_namespace *ns,
 	fs_actions[num_fs_actions++].action = tmp_action;
 	(*ractions)[num_actions++].action = tmp_action;
 
+	rule_actions = kmemdup_array(fs_actions, num_fs_actions,
+				     sizeof(*fs_actions), GFP_KERNEL);
+	if (!rule_actions) {
+		err = -ENOMEM;
+		goto free_actions;
+	}
+	kfree(fs_actions);
 	kfree(dest_actions);
 
 	/* Actions created specifically for this rule will be destroyed
 	 * once rule is deleted.
 	 */
 	fte->fs_hws_rule.num_fs_actions = num_fs_actions;
-	fte->fs_hws_rule.hws_fs_actions = fs_actions;
+	fte->fs_hws_rule.hws_fs_actions = rule_actions;
 
 	return 0;
 
-- 
2.43.0

Re: [PATCH net-next 2/2] net/mlx5: HWS, shrink FTE action array to fit

[sashiko-bot]

> An FTE keeps the actions it must release in the array used to build
> them. This is a 1 KB allocation sized for MLX5_FLOW_CONTEXT_ACTION_MAX
> entries while a rule rarely needs more than three. Keep a copy sized to
> the actions in use.
> 
> Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261009052103.3621855-1-acassen@corp.free.fr?part=2

Re: [PATCH net-next 2/2] net/mlx5: HWS, shrink FTE action array to fit

[Simon Horman]

On Fri, Oct 09, 2026 at 07:21:01AM +0200, Alexandre Cassen wrote:
> An FTE keeps the actions it must release in the array used to build
> them. This is a 1 KB allocation sized for MLX5_FLOW_CONTEXT_ACTION_MAX
> entries while a rule rarely needs more than three. Keep a copy sized to
> the actions in use.
> 
> Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>

Reviewed-by: Simon Horman <horms@kernel.org>