linux-kernel - Re: [PATCH net-next v07 8/9] hinic3: Add netdev notifier interfaces

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Message-ID: <ea2ce128-537a-4718-aa70-d9192cfb94b8@redhat.com>
Date: Tue, 25 Nov 2025 11:46:46 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Fan Gong <gongfan1@...wei.com>, Zhu Yikai <zhuyikai1@...artners.com>,
 netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Simon Horman <horms@...nel.org>, Andrew Lunn <andrew+netdev@...n.ch>,
 Markus Elfring <Markus.Elfring@....de>,
 Pavan Chebbi <pavan.chebbi@...adcom.com>,
 ALOK TIWARI <alok.a.tiwari@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 luosifu <luosifu@...wei.com>, Xin Guo <guoxin09@...wei.com>,
 Shen Chenyang <shenchenyang1@...ilicon.com>,
 Zhou Shuai <zhoushuai28@...wei.com>, Wu Like <wulike1@...wei.com>,
 Shi Jing <shijing34@...wei.com>, Luo Yang <luoyang82@...artners.com>,
 Meny Yossefi <meny.yossefi@...wei.com>, Gur Stavi <gur.stavi@...wei.com>
Subject: Re: [PATCH net-next v07 8/9] hinic3: Add netdev notifier interfaces

On 11/19/25 1:43 PM, Fan Gong wrote:
> Add netdev notifier interfaces.
> As we stipulate that netdevices with a vlan depth greater than 1
> should disable the offload feature, Layer 1 vlan netdevices use
> notifier to modify vlan_features.

As mentioned by Jakub in the previous revision, the net stack can send
packets with multiple stacked vlans. You need to implement
ndo_features_check(), check for the problematic packet layout there and
ev return a smaller features check excluding the relevant offloads.

> +static u16 hinic3_get_vlan_depth(struct net_device *netdev)
> +{
> +	u16 vlan_depth = 0;
> +
> +#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
> +	while (is_vlan_dev(netdev)) {
> +		netdev = vlan_dev_priv(netdev)->real_dev;
> +		vlan_depth++;
> +	}
> +#endif
> +	return vlan_depth;

AFAICS the above can return any number >=
HINIC3_MAX_VLAN_DEPTH_OFFLOAD_SUPPORT ...

> +}
> +
> +static int hinic3_netdev_event(struct notifier_block *notifier,
> +			       unsigned long event, void *ptr)
> +{
> +	struct net_device *ndev = netdev_notifier_info_to_dev(ptr);
> +	struct hinic3_nic_dev *nic_dev = netdev_priv(ndev);
> +	u16 vlan_depth;
> +
> +	if (!is_vlan_dev(ndev))
> +		return NOTIFY_DONE;
> +
> +	netdev_hold(ndev, &nic_dev->tracker, GFP_ATOMIC);
> +
> +	switch (event) {
> +	case NETDEV_REGISTER:
> +		vlan_depth = hinic3_get_vlan_depth(ndev);
> +		if (vlan_depth == HINIC3_MAX_VLAN_DEPTH_OFFLOAD_SUPPORT)

... so here you should use '>='> +			ndev->vlan_features &=
(~HINIC3_VLAN_CLEAR_OFFLOAD);
> +
> +		break;
> +
> +	default:
> +		break;
> +	}
> +
> +	netdev_put(ndev, &nic_dev->tracker);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block hinic3_netdev_notifier = {
> +	.notifier_call = hinic3_netdev_event,
> +};
> +
>  static void init_intr_coal_param(struct net_device *netdev)
>  {
>  	struct hinic3_nic_dev *nic_dev = netdev_priv(netdev);
> @@ -309,6 +364,36 @@ static int hinic3_set_default_hw_feature(struct net_device *netdev)
>  	return 0;
>  }
>  
> +static void hinic3_register_notifier(struct net_device *netdev)
> +{
> +	struct hinic3_nic_dev *nic_dev = netdev_priv(netdev);
> +	int err;
> +
> +	mutex_lock(&hinic3_netdev_notifiers_mutex);
> +	hinic3_netdev_notifiers_ref_cnt++;
> +	if (hinic3_netdev_notifiers_ref_cnt == 1) {

Why do you need this notifier accounting? Instead you should be able to
call hinic3_register_notifier() only once.

/P