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

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Message-ID: <e3065103-d38c-1b80-5b61-71e8ba017e71@broadcom.com>
Date:   Thu, 1 Jun 2023 11:37:43 -0700
From:   Florian Fainelli <florian.fainelli@...adcom.com>
To:     Justin Chen <justin.chen@...adcom.com>,
        Simon Horman <simon.horman@...igine.com>
Cc:     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>,
        Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH net-next] ethtool: ioctl: improve error checking for
 set_wol

On 6/1/23 11:27, Justin Chen wrote:
> 
> 
> On 6/1/23 9:22 AM, Justin Chen wrote:
>>
>>
>> On 6/1/2023 8:55 AM, Simon Horman wrote:
>>> + Daniil Tatianin <d-tatianin@...dex-team.ru>, Andrew Lunn 
>>> <andrew@...n.ch>
>>>    as per ./scripts/get_maintainer.pl --git-min-percent 25 
>>> net/ethtool/ioctl.c
>>>
>>> On Wed, May 31, 2023 at 01:53:49PM -0700, Justin Chen wrote:
>>>> The netlink version of set_wol checks for not supported wolopts and 
>>>> avoids
>>>> setting wol when the correct wolopt is already set. If we do the 
>>>> same with
>>>> the ioctl version then we can remove these checks from the driver 
>>>> layer.
>>>
>>> Hi Justin,
>>>
>>> Are you planning follow-up patches for the driver layer?
>>>
>>
>> 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.
-- 
Florian


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