linux-kernel - Re: [PATCH net-next] ethtool: ioctl: improve error checking for set

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Message-ID: <312c1067-aab6-4f04-b18e-ba1b7a0d1427@lunn.ch>
Date:   Thu, 1 Jun 2023 20:48:53 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Florian Fainelli <florian.fainelli@...adcom.com>
Cc:     Justin Chen <justin.chen@...adcom.com>,
        Simon Horman <simon.horman@...igine.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, bcm-kernel-feedback-list@...adcom.com,
        Daniil Tatianin <d-tatianin@...dex-team.ru>,
        Yuiko Oshino <yuiko.oshino@...rochip.com>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>,
        Steen Hegelund <steen.hegelund@...rochip.com>,
        Rakesh Sankaranarayanan <rakesh.sankaranarayanan@...rochip.com>,
        Arun Ramadoss <arun.ramadoss@...rochip.com>
Subject: Re: [PATCH net-next] ethtool: ioctl: improve error checking for
 set_wol

> > > I was planning to for the Broadcom drivers since those I can test.
> > > But I could do it across the board if that is preferred.
> > > 
> > > > > Signed-off-by: Justin Chen <justin.chen@...adcom.com>
> > > > > ---
> > > > >   net/ethtool/ioctl.c | 14 ++++++++++++--
> > > > >   1 file changed, 12 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
> > > > > index 6bb778e10461..80f456f83db0 100644
> > > > > --- a/net/ethtool/ioctl.c
> > > > > +++ b/net/ethtool/ioctl.c
> > > > > @@ -1436,15 +1436,25 @@ static int ethtool_get_wol(struct
> > > > > net_device *dev, char __user *useraddr)
> > > > >   static int ethtool_set_wol(struct net_device *dev, char
> > > > > __user *useraddr)
> > > > >   {
> > > > > -    struct ethtool_wolinfo wol;
> > > > > +    struct ethtool_wolinfo wol, cur_wol;
> > > > >       int ret;
> > > > > -    if (!dev->ethtool_ops->set_wol)
> > > > > +    if (!dev->ethtool_ops->get_wol || !dev->ethtool_ops->set_wol)
> > > > >           return -EOPNOTSUPP;
> > > > 
> > > > Are there cases where (in-tree) drivers provide set_wol byt not get_wol?
> > > > If so, does this break their set_wol support?
> > > > 
> > > 
> > > My original thought was to match netlink set wol behavior. So
> > > drivers that do that won't work with netlink set_wol right now. I'll
> > > skim around to see if any drivers do this. But I would reckon this
> > > should be a driver fix.
> > > 
> > > Thanks,
> > > Justin
> > > 
> > 
> > I see a driver at drivers/net/phy/microchip.c. But this is a phy driver
> > set_wol hook.
> 
> That part of the driver appears to be dead code. It attempts to pretend to
> support Wake-on-LAN, but it does not do any specific programming of wake-up
> filters, nor does it implement get_wol. It also does not make use of the
> recently introduced PHY_ALWAYS_CALL_SUSPEND flag.
> 
> When it is time to determine whether to suspend the PHY or not, eventually
> phy_suspend() will call phy_ethtool_get_wol(). Since no get_wol is
> implemented, the wol.wolopts will remain zero, therefore we will just
> suspend the PHY.
> 
> I suspect this was added to work around MAC drivers that may forcefully try
> to suspend the PHY, but that should not even be possible these days.
> 
> I would just remove that logic from microchip.c entirely.

The Microchip developers are reasonably responsive. So we should Cc:
them.

	Andrew