netdev - Re: [PATCH] net: phy: Trigger link_change_notify on PHY

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Date:   Tue, 5 Jan 2021 17:05:01 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Marek Vasut <marex@...x.de>, netdev@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH] net: phy: Trigger link_change_notify on PHY_HALTED

On Tue, Jan 05, 2021 at 05:58:21PM +0100, Heiner Kallweit wrote:
> On 05.01.2021 17:11, Marek Vasut wrote:
> > @@ -1021,8 +1022,17 @@ void phy_stop(struct phy_device *phydev)
> >  	if (phydev->sfp_bus)
> >  		sfp_upstream_stop(phydev->sfp_bus);
> >  
> > +	old_state = phydev->state;
> >  	phydev->state = PHY_HALTED;
> >  
> > +	if (old_state != phydev->state) {
> 
> This check shouldn't be needed because it shouldn't happen that
> phy_stop() is called from status PHY_HALTED. In this case the
> WARN() a few lines above would have fired already.

That is incorrect. If an error happens with the phy, phy_error() will
be called, which sets phydev->state = PHY_HALTED. If you then
subsequently take the interface down, phy_stop() will be called, but
phydev->state will be set to PHY_HALTED.

This is a long standing bug since you changed the code, and I think is
something I've reported previously, since I've definitely encountered
it.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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