netdev - RE: [PATCH net-next] ethtool: ioctl: improve error checking for set

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Message-ID: <SN6PR11MB29261BD713D2FE27F2FBCCD3E749A@SN6PR11MB2926.namprd11.prod.outlook.com>
Date: Thu, 1 Jun 2023 20:41:41 +0000
From: <Woojung.Huh@...rochip.com>
To: <justin.chen@...adcom.com>, <andrew@...n.ch>,
	<florian.fainelli@...adcom.com>
CC: <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>, <d-tatianin@...dex-team.ru>,
	<Yuiko.Oshino@...rochip.com>, <Horatiu.Vultur@...rochip.com>,
	<Steen.Hegelund@...rochip.com>, <Rakesh.Sankaranarayanan@...rochip.com>,
	<Arun.Ramadoss@...rochip.com>, <UNGLinuxDriver@...rochip.com>
Subject: RE: [PATCH net-next] ethtool: ioctl: improve error checking for
 set_wol

> On 6/1/23 11:48 AM, Andrew Lunn wrote:
> >>>> 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.


set_wol in drivers/net/phy/microchip.c is used to set the flag
to avoid PHY power down at suspend time.
Looks it is old-fashioned now because frame work is not calling suspend
after calling get_wol. We will make a patch for it.

BTW, this patch is checking MAC driver set_wol and get_wol.
So I don't think it breaks drivers/net/phy/microchip.c suspend operation anyway.

Thanks.
Woojung