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Message-ID: <ZozPSl6opHYYdO-A@pengutronix.de>
Date: Tue, 9 Jul 2024 07:48:58 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Woojung.Huh@...rochip.com
Cc: mkubecek@...e.cz, davem@...emloft.net, edumazet@...gle.com,
kuba@...nel.org, pabeni@...hat.com, jiri@...nulli.us,
vladimir.oltean@....com, andrew@...n.ch,
Arun.Ramadoss@...rochip.com, kernel@...gutronix.de,
netdev@...r.kernel.org, UNGLinuxDriver@...rochip.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v2 1/1] ethtool: netlink: do not return SQI value if
link is down
Hi Woojung,
On Mon, Jul 08, 2024 at 04:31:53PM +0000, Woojung.Huh@...rochip.com wrote:
> Hi Oleksij,
>
> > diff --git a/net/ethtool/linkstate.c b/net/ethtool/linkstate.c
> > index b2de2108b356a..4efd327ba5d92 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);
> > @@ -62,6 +66,16 @@ static int linkstate_get_sqi_max(struct net_device *dev)
> > return ret;
> > };
> >
> > +static bool linkstate_sqi_critical_error(int sqi)
> > +{
> > + return sqi < 0 && sqi != -EOPNOTSUPP && sqi != -ENETDOWN;
> > +}
> > +
> > +static bool linkstate_sqi_valid(struct linkstate_reply_data *data)
> > +{
> > + return data->sqi >= 0 && data->sqi_max >= 0;
>
> If PHY driver has get_sqi, but not get_sqi_max, then data->sqi could have
> a valid value, but data->sqi_max will have -EOPNOTSUPP.
> In this case, linkstate_sqi_valid() will return FALSE and not getting
> SQI value at all.
SQI without max will not able to describe quality of the link, it is
just value saying nothing to the user.
> If both APIs are required, then we could add another condition of
> data->sqi <= data->sqi_max in linkstate_sqi_valid()
Ack. I was thinking about it, but was not sure if it is a good idea. This
will silently filer our a bag. Passing a baggy value to the users space
is not good too. I'll fix.
> And, beside this, calling linkstate_get_sqi and linkstate_get_sqi_max
> could be moved under "if (dev->flags & IFF_UP)" with setting default
> value to data->sqi & data->sqi_max.
IFF_UP is administrative up state, it is not the link/L1 up. sqi_max and
sqi should be initialized anyway, otherwise we will show 0/0 if
interface is in admin down.
Regards,
Oleksij
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