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

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Message-ID: <ZoebO_i6P33iX4B1@pengutronix.de>
Date: Fri, 5 Jul 2024 09:05:31 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Andrew Lunn <andrew@...n.ch>
Cc: Michal Kubecek <mkubecek@...e.cz>, Woojung.Huh@...rochip.com,
	Arun Ramadoss <arun.ramadoss@...rochip.com>,
	Jiri Pirko <jiri@...nulli.us>,
	Vladimir Oltean <vladimir.oltean@....com>,
	linux-kernel@...r.kernel.org, UNGLinuxDriver@...rochip.com,
	Eric Dumazet <edumazet@...gle.com>, kernel@...gutronix.de,
	netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net v1 1/1] ethtool: netlink: do not return SQI value if
 link is down

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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