Re: [RFC PATCH v3 3/5] Add ndo_hwtstamp_get/set support to vlan code path

[Vladimir Oltean <vladimir.oltean@nxp.com>]

On Wed, Apr 05, 2023 at 12:33:23AM -0600, Maxim Georgiev wrote:
> This patch makes VLAN subsystem to use the newly introduced
> ndo_hwtstamp_get/set API to pass hw timestamp requests to
> underlying NIC drivers in case if these drivers implement
> ndo_hwtstamp_get/set functions. Otherwise VLAN┬Ěsubsystem

Strange symbols (┬Ě).

> falls back to calling ndo_eth_ioctl.
> 
> Suggested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> Signed-off-by: Maxim Georgiev <glipus@gmail.com>
> ---
>  net/8021q/vlan_dev.c | 42 +++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 41 insertions(+), 1 deletion(-)
> 
> diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
> index 5920544e93e8..66d54c610aa5 100644
> --- a/net/8021q/vlan_dev.c
> +++ b/net/8021q/vlan_dev.c
> @@ -353,6 +353,44 @@ static int vlan_dev_set_mac_address(struct net_device *dev, void *p)
>  	return 0;
>  }
>  
> +static int vlan_dev_hwtstamp(struct net_device *dev, struct ifreq *ifr, int cmd)
> +{
> +	const struct net_device_ops *ops = dev->netdev_ops;
> +	struct kernel_hwtstamp_config kernel_config = {};
> +	struct hwtstamp_config config;
> +	int err;
> +
> +	if (!netif_device_present(dev))
> +		return -ENODEV;
> +
> +	if ((cmd == SIOCSHWTSTAMP && !ops->ndo_hwtstamp_set) ||
> +	    (cmd == SIOCGHWTSTAMP && !ops->ndo_hwtstamp_get)) {
> +		if (ops->ndo_eth_ioctl) {
> +			return ops->ndo_eth_ioctl(real_dev, &ifr, cmd);
> +		else
> +			return -EOPNOTSUPP;
> +	}
> +
> +	kernel_config.ifr = ifr;
> +	if (cmd == SIOCSHWTSTAMP) {
> +		if (copy_from_user(&config, ifr->ifr_data, sizeof(config)))
> +			return -EFAULT;
> +
> +		hwtstamp_config_to_kernel(&kernel_config, &config);
> +		err = ops->ndo_hwtstamp_set(dev, &kernel_config, NULL);
> +	} else if (cmd == SIOCGHWTSTAMP) {
> +		err = ops->ndo_hwtstamp_get(dev, &kernel_config, NULL);
> +	}
> +
> +	if (err)
> +		return err;
> +
> +	hwtstamp_kernel_to_config(&config, &kernel_config);
> +	if (copy_to_user(ifr->ifr_data, &config, sizeof(config)))
> +		return -EFAULT;
> +	return 0;
> +}
> +
>  static int vlan_dev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
>  {
>  	struct net_device *real_dev = vlan_dev_priv(dev)->real_dev;
> @@ -368,10 +406,12 @@ static int vlan_dev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
>  		if (!net_eq(dev_net(dev), dev_net(real_dev)))
>  			break;
>  		fallthrough;
> +	case SIOCGHWTSTAMP:
> +		err = vlan_dev_hwtstamp(real_dev, &ifrr, cmd);
> +		break;
>  	case SIOCGMIIPHY:
>  	case SIOCGMIIREG:
>  	case SIOCSMIIREG:
> -	case SIOCGHWTSTAMP:

I would recommend also making vlan_dev_hwtstamp() be called from the
VLAN driver's ndo_hwtstamp_set() rather than from ndo_eth_ioctl().

My understanding of Jakub's suggestion to (temporarily) stuff ifr
inside kernel_config was to do that from top-level net/core/dev_ioctl.c,
not from the VLAN driver.

>  		if (netif_device_present(real_dev) && ops->ndo_eth_ioctl)
>  			err = ops->ndo_eth_ioctl(real_dev, &ifrr, cmd);
>  		break;
> -- 
> 2.39.2
>