[PATCH net v1 1/1] ethtool: netlink: do not return SQI value if link is down

[PATCH net v1 1/1] ethtool: netlink: do not return SQI value if link is down

[Oleksij Rempel]

Do not attach SQI value if link is down. "SQI values are only valid if link-up
condition is present" per OpenAlliance specification of 100Base-T1
Interoperability Test suite [1]. The same rule would apply for other link
types.

[1] https://opensig.org/automotive-ethernet-specifications/#

Fixes: 8066021915924 ("ethtool: provide UAPI for PHY Signal Quality Index (SQI)")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 net/ethtool/linkstate.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/ethtool/linkstate.c b/net/ethtool/linkstate.c
index b2de2108b356a..370ae628b13a4 100644
--- a/net/ethtool/linkstate.c
+++ b/net/ethtool/linkstate.c
@@ -37,6 +37,8 @@ static int linkstate_get_sqi(struct net_device *dev)
 	mutex_lock(&phydev->lock);
 	if (!phydev->drv || !phydev->drv->get_sqi)
 		ret = -EOPNOTSUPP;
+	else if (!phydev->link)
+		ret = -ENETDOWN;
 	else
 		ret = phydev->drv->get_sqi(phydev);
 	mutex_unlock(&phydev->lock);
@@ -55,6 +57,8 @@ static int linkstate_get_sqi_max(struct net_device *dev)
 	mutex_lock(&phydev->lock);
 	if (!phydev->drv || !phydev->drv->get_sqi_max)
 		ret = -EOPNOTSUPP;
+	else if (!phydev->link)
+		ret = -ENETDOWN;
 	else
 		ret = phydev->drv->get_sqi_max(phydev);
 	mutex_unlock(&phydev->lock);
@@ -93,12 +97,12 @@ static int linkstate_prepare_data(const struct ethnl_req_info *req_base,
 	data->link = __ethtool_get_link(dev);
 
 	ret = linkstate_get_sqi(dev);
-	if (ret < 0 && ret != -EOPNOTSUPP)
+	if (ret < 0 && ret != -EOPNOTSUPP && ret != -ENETDOWN)
 		goto out;
 	data->sqi = ret;
 
 	ret = linkstate_get_sqi_max(dev);
-	if (ret < 0 && ret != -EOPNOTSUPP)
+	if (ret < 0 && ret != -EOPNOTSUPP && ret != -ENETDOWN)
 		goto out;
 	data->sqi_max = ret;
 
@@ -136,10 +140,10 @@ static int linkstate_reply_size(const struct ethnl_req_info *req_base,
 	len = nla_total_size(sizeof(u8)) /* LINKSTATE_LINK */
 		+ 0;
 
-	if (data->sqi != -EOPNOTSUPP)
+	if (data->sqi != -EOPNOTSUPP && data->sqi != -ENETDOWN)
 		len += nla_total_size(sizeof(u32));
 
-	if (data->sqi_max != -EOPNOTSUPP)
+	if (data->sqi_max != -EOPNOTSUPP && data->sqi_max != -ENETDOWN)
 		len += nla_total_size(sizeof(u32));
 
 	if (data->link_ext_state_provided)
@@ -164,11 +168,11 @@ static int linkstate_fill_reply(struct sk_buff *skb,
 	    nla_put_u8(skb, ETHTOOL_A_LINKSTATE_LINK, !!data->link))
 		return -EMSGSIZE;
 
-	if (data->sqi != -EOPNOTSUPP &&
+	if (data->sqi != -EOPNOTSUPP && data->sqi != -ENETDOWN &&
 	    nla_put_u32(skb, ETHTOOL_A_LINKSTATE_SQI, data->sqi))
 		return -EMSGSIZE;
 
-	if (data->sqi_max != -EOPNOTSUPP &&
+	if (data->sqi_max != -EOPNOTSUPP && data->sqi_max != -ENETDOWN &&
 	    nla_put_u32(skb, ETHTOOL_A_LINKSTATE_SQI_MAX, data->sqi_max))
 		return -EMSGSIZE;
 
-- 
2.39.2

Re: [PATCH net v1 1/1] ethtool: netlink: do not return SQI value if link is down

[Andrew Lunn]

On Thu, Jul 04, 2024 at 07:40:07AM +0200, Oleksij Rempel wrote:
> Do not attach SQI value if link is down. "SQI values are only valid if link-up
> condition is present" per OpenAlliance specification of 100Base-T1
> Interoperability Test suite [1]. The same rule would apply for other link
> types.
> 
> [1] https://opensig.org/automotive-ethernet-specifications/#
> 
> Fixes: 8066021915924 ("ethtool: provide UAPI for PHY Signal Quality Index (SQI)")
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  net/ethtool/linkstate.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/net/ethtool/linkstate.c b/net/ethtool/linkstate.c
> index b2de2108b356a..370ae628b13a4 100644
> --- a/net/ethtool/linkstate.c
> +++ b/net/ethtool/linkstate.c
> @@ -37,6 +37,8 @@ static int linkstate_get_sqi(struct net_device *dev)
>  	mutex_lock(&phydev->lock);
>  	if (!phydev->drv || !phydev->drv->get_sqi)
>  		ret = -EOPNOTSUPP;
> +	else if (!phydev->link)
> +		ret = -ENETDOWN;
>  	else
>  		ret = phydev->drv->get_sqi(phydev);
>  	mutex_unlock(&phydev->lock);
> @@ -55,6 +57,8 @@ static int linkstate_get_sqi_max(struct net_device *dev)
>  	mutex_lock(&phydev->lock);
>  	if (!phydev->drv || !phydev->drv->get_sqi_max)
>  		ret = -EOPNOTSUPP;
> +	else if (!phydev->link)
> +		ret = -ENETDOWN;
>  	else
>  		ret = phydev->drv->get_sqi_max(phydev);
>  	mutex_unlock(&phydev->lock);

I guess this part is optional. I think i've always seen hard coded
values. But this is O.K.

> @@ -93,12 +97,12 @@ static int linkstate_prepare_data(const struct ethnl_req_info *req_base,
>  	data->link = __ethtool_get_link(dev);
>  
>  	ret = linkstate_get_sqi(dev);
> -	if (ret < 0 && ret != -EOPNOTSUPP)
> +	if (ret < 0 && ret != -EOPNOTSUPP && ret != -ENETDOWN)
>  		goto out;
>  	data->sqi = ret;

So data->sqi becomes -ENETDOWN 


> -	if (data->sqi != -EOPNOTSUPP &&
> +	if (data->sqi != -EOPNOTSUPP && data->sqi != -ENETDOWN &&
>  	    nla_put_u32(skb, ETHTOOL_A_LINKSTATE_SQI, data->sqi))
>  		return -EMSGSIZE;

Thinking about the old code, if the driver returned something other
than -EOPNOTSUPP, it looks like the error code would make it to user
space. Is ethtool/iproute2 setup to correctly handle this? If it is,
maybe pass the -ENETDOWN to user space?

	Andrew

Re: [PATCH net v1 1/1] ethtool: netlink: do not return SQI value if link is down

[Oleksij Rempel]

On Thu, Jul 04, 2024 at 04:01:31PM +0200, Andrew Lunn wrote:
...
> >  	ret = linkstate_get_sqi(dev);
> > -	if (ret < 0 && ret != -EOPNOTSUPP)
> > +	if (ret < 0 && ret != -EOPNOTSUPP && ret != -ENETDOWN)
> >  		goto out;
> >  	data->sqi = ret;
> 
> So data->sqi becomes -ENETDOWN 
> 
> 
> > -	if (data->sqi != -EOPNOTSUPP &&
> > +	if (data->sqi != -EOPNOTSUPP && data->sqi != -ENETDOWN &&
> >  	    nla_put_u32(skb, ETHTOOL_A_LINKSTATE_SQI, data->sqi))
> >  		return -EMSGSIZE;
> 
> Thinking about the old code, if the driver returned something other
> than -EOPNOTSUPP, it looks like the error code would make it to user
> space. Is ethtool/iproute2 setup to correctly handle this? If it is,
> maybe pass the -ENETDOWN to user space?

In current state with ethtool v6.5 i'll get following results.
If no -ENETDOWN is returned:
Settings for spe4:
        Supported ports: [ TP ]
        Supported link modes:   100baseT1/Full
        Supported pause frame use: No
        Supports auto-negotiation: No
        Supported FEC modes: Not reported
        Advertised link modes:  100baseT1/Full
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Advertised FEC modes: Not reported
        Speed: 100Mb/s
        Duplex: Full
        Auto-negotiation: off
        master-slave cfg: forced slave
        master-slave status: unknown
        Port: Twisted Pair
        PHYAD: 6
        Transceiver: external
        MDI-X: Unknown
        Supports Wake-on: d
        Wake-on: d
        Link detected: no

If -ENETDOWN is returned:
Settings for spe4:
        Supported ports: [ TP ]
        Supported link modes:   100baseT1/Fulli
        Supported pause frame use: No
        Supports auto-negotiation: No
        Supported FEC modes: Not reported
        Advertised link modes:  100baseT1/Full
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Advertised FEC modes: Not reported
        Speed: 100Mb/s
        Duplex: Full
        Auto-negotiation: off
        master-slave cfg: forced slave
        master-slave status: unknown
        Port: Twisted Pair
        PHYAD: 6
        Transceiver: external
        MDI-X: Unknown
        Supports Wake-on: d
        Wake-on: d
netlink error: Network is down

Instead of "Link detected: no", we will get netlink error.

Regards,
Oleksij
-- 
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Re: [PATCH net v1 1/1] ethtool: netlink: do not return SQI value if link is down

[Jakub Kicinski]

On Thu,  4 Jul 2024 07:40:07 +0200 Oleksij Rempel wrote:
>  	if (!phydev->drv || !phydev->drv->get_sqi)
>  		ret = -EOPNOTSUPP;
> +	else if (!phydev->link)
> +		ret = -ENETDOWN;

Can we stick to EOPNOTSUPP for the link down case as well?
We're consuming the error, the exact value doesn't matter.
Or let's add a helper which checks the int sqi in all it's
incarnations for validity:

static bool linkstate_sqi_no_data(int sqi)
{
	return sqi == -EOPNOTSUPP || sqi == -ENETDOWN;
}

Re: [PATCH net v1 1/1] ethtool: netlink: do not return SQI value if link is down

[Andrew Lunn]

> If -ENETDOWN is returned:
> Settings for spe4:
>         Supported ports: [ TP ]
>         Supported link modes:   100baseT1/Fulli
>         Supported pause frame use: No
>         Supports auto-negotiation: No
>         Supported FEC modes: Not reported
>         Advertised link modes:  100baseT1/Full
>         Advertised pause frame use: No
>         Advertised auto-negotiation: No
>         Advertised FEC modes: Not reported
>         Speed: 100Mb/s
>         Duplex: Full
>         Auto-negotiation: off
>         master-slave cfg: forced slave
>         master-slave status: unknown
>         Port: Twisted Pair
>         PHYAD: 6
>         Transceiver: external
>         MDI-X: Unknown
>         Supports Wake-on: d
>         Wake-on: d
> netlink error: Network is down
> 
> Instead of "Link detected: no", we will get netlink error.

Thanks. This is not great. There was a slim chance it looked at each
individual return value, and would of put "SQI: Network is down", but
it does not. So not including the value does seem the best.

	Andrew