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

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Message-ID: <81cf54eb-98a0-e786-3526-fa422e0c504c@broadcom.com>
Date:   Thu, 1 Jun 2023 11:58:58 -0700
From:   Justin Chen <justin.chen@...adcom.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <florian.fainelli@...adcom.com>
Cc:     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>,
        woojung.huh@...rochip.com, UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH net-next] ethtool: ioctl: improve error checking for
 set_wol

+ Woojung, UNGLinuxDriver

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.
> 
> 	Andrew

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