Re: [PATCH net-next 2/2] net: ethernet: mediatek: mtk_ppe: prefer newly added l2 flows over existing ones

[Simon Horman <simon.horman@corigine.com>]

On Tue, Mar 21, 2023 at 02:36:09PM +0100, Felix Fietkau wrote:
> When a device is roaming between interfaces and a new flow entry is created,
> we should assume that its output device is more up to date than whatever
> entry existed already.

As per patch 1/2. checkpatch complains that the patch description
has lines more than 75 characters long.

That aside, this change looks good to me.
But I'm wondering if it is fixing a bug.
Or just improving something suboptimal (form a user experience POV).

> 
> Signed-off-by: Felix Fietkau <nbd@nbd.name>

> ---
>  drivers/net/ethernet/mediatek/mtk_ppe.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_ppe.c b/drivers/net/ethernet/mediatek/mtk_ppe.c
> index 6883eb34cd8b..5e150007bb7d 100644
> --- a/drivers/net/ethernet/mediatek/mtk_ppe.c
> +++ b/drivers/net/ethernet/mediatek/mtk_ppe.c
> @@ -580,10 +580,20 @@ void mtk_foe_entry_clear(struct mtk_ppe *ppe, struct mtk_flow_entry *entry)
>  static int
>  mtk_foe_entry_commit_l2(struct mtk_ppe *ppe, struct mtk_flow_entry *entry)
>  {
> +	struct mtk_flow_entry *prev;
> +
>  	entry->type = MTK_FLOW_TYPE_L2;
>  
> -	return rhashtable_insert_fast(&ppe->l2_flows, &entry->l2_node,
> -				      mtk_flow_l2_ht_params);
> +	prev = rhashtable_lookup_get_insert_fast(&ppe->l2_flows, &entry->l2_node,
> +						 mtk_flow_l2_ht_params);
> +	if (likely(!prev))
> +		return 0;
> +
> +	if (IS_ERR(prev))
> +		return PTR_ERR(prev);
> +
> +	return rhashtable_replace_fast(&ppe->l2_flows, &prev->l2_node,
> +				       &entry->l2_node, mtk_flow_l2_ht_params);
>  }
>  
>  int mtk_foe_entry_commit(struct mtk_ppe *ppe, struct mtk_flow_entry *entry)
> -- 
> 2.39.0
>