Re: [PATCH RFC V1 net-next 1/4] net: ethtool: Refactor identical get_ts_info implementations.

From: Vladimir Oltean
Date: Thu Jan 20 2022 - 11:13:35 EST


On Mon, Jan 03, 2022 at 03:25:52PM -0800, Richard Cochran wrote:
> Both the vlan and the bonding drivers call their "real" device driver
> in order to report the time stamping capabilities. Provide a core
> ethtool helper function to avoid copy/paste in the stack.
>
> Signed-off-by: Richard Cochran <richardcochran@xxxxxxxxx>
> ---

Reviewed-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>

> drivers/net/bonding/bond_main.c | 14 ++------------
> include/linux/ethtool.h | 8 ++++++++
> net/8021q/vlan_dev.c | 15 +--------------
> net/ethtool/common.c | 6 ++++++
> 4 files changed, 17 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index b60e22f6394a..f28b88b67b9e 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -5353,23 +5353,13 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev,
> struct ethtool_ts_info *info)
> {
> struct bonding *bond = netdev_priv(bond_dev);
> - const struct ethtool_ops *ops;
> struct net_device *real_dev;
> - struct phy_device *phydev;
>
> rcu_read_lock();
> real_dev = bond_option_active_slave_get_rcu(bond);
> rcu_read_unlock();

Side note: I'm a bit confused about this rcu_read_lock() ->
rcu_dereference_protected() -> rcu_read_unlock() pattern, and use of the
real_dev outside the RCU critical section. Isn't ->get_ts_info()
protected by the rtnl_mutex? Shouldn't there be a
bond_option_active_slave_get() which uses rtnl_dereference()?
I see the code has been recently added by Hangbin Liu.

> - if (real_dev) {
> - ops = real_dev->ethtool_ops;
> - phydev = real_dev->phydev;
> -
> - if (phy_has_tsinfo(phydev)) {
> - return phy_ts_info(phydev, info);
> - } else if (ops->get_ts_info) {
> - return ops->get_ts_info(real_dev, info);
> - }
> - }
> + if (real_dev)
> + return ethtool_get_ts_info_by_layer(real_dev, info);
>
> info->so_timestamping = SOF_TIMESTAMPING_RX_SOFTWARE |
> SOF_TIMESTAMPING_SOFTWARE;
> diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
> index a26f37a27167..1d72344493bb 100644
> --- a/include/linux/ethtool.h
> +++ b/include/linux/ethtool.h
> @@ -824,6 +824,14 @@ ethtool_params_from_link_mode(struct ethtool_link_ksettings *link_ksettings,
> */
> int ethtool_get_phc_vclocks(struct net_device *dev, int **vclock_index);
>
> +/**
> + * ethtool_get_ts_info_by_layer - Obtains time stamping capabilities from the MAC or PHY layer.
> + * @dev: pointer to net_device structure
> + * @info: buffer to hold the result
> + * Returns zero on sauces, non-zero otherwise.
> + */
> +int ethtool_get_ts_info_by_layer(struct net_device *dev, struct ethtool_ts_info *info);
> +
> /**
> * ethtool_sprintf - Write formatted string to ethtool string data
> * @data: Pointer to start of string to update
> diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
> index 26d031a43cc1..c645d7c46d78 100644
> --- a/net/8021q/vlan_dev.c
> +++ b/net/8021q/vlan_dev.c
> @@ -679,20 +679,7 @@ static int vlan_ethtool_get_ts_info(struct net_device *dev,
> struct ethtool_ts_info *info)
> {
> const struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
> - const struct ethtool_ops *ops = vlan->real_dev->ethtool_ops;
> - struct phy_device *phydev = vlan->real_dev->phydev;
> -
> - if (phy_has_tsinfo(phydev)) {
> - return phy_ts_info(phydev, info);
> - } else if (ops->get_ts_info) {
> - return ops->get_ts_info(vlan->real_dev, info);
> - } else {
> - info->so_timestamping = SOF_TIMESTAMPING_RX_SOFTWARE |
> - SOF_TIMESTAMPING_SOFTWARE;
> - info->phc_index = -1;
> - }
> -
> - return 0;
> + return ethtool_get_ts_info_by_layer(vlan->real_dev, info);
> }
>
> static void vlan_dev_get_stats64(struct net_device *dev,
> diff --git a/net/ethtool/common.c b/net/ethtool/common.c
> index 0c5210015911..651d18eef589 100644
> --- a/net/ethtool/common.c
> +++ b/net/ethtool/common.c
> @@ -569,6 +569,12 @@ int ethtool_get_phc_vclocks(struct net_device *dev, int **vclock_index)
> }
> EXPORT_SYMBOL(ethtool_get_phc_vclocks);
>
> +int ethtool_get_ts_info_by_layer(struct net_device *dev, struct ethtool_ts_info *info)
> +{
> + return __ethtool_get_ts_info(dev, info);
> +}
> +EXPORT_SYMBOL(ethtool_get_ts_info_by_layer);

I would probably replace all __ethtool_get_ts_info() function name
occurrences with ethtool_get_ts_info_by_layer() (since it isn't a bad
name) to make it absolutely clear that it's recursive for VLAN and bond
interfaces. But maybe that's just me.

> +
> const struct ethtool_phy_ops *ethtool_phy_ops;
>
> void ethtool_set_ethtool_phy_ops(const struct ethtool_phy_ops *ops)
> --
> 2.20.1
>