Re: [PATCH net-next] ethtool: ioctl: improve error checking for set_wol

[Justin Chen <justin.chen@broadcom.com>]

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On 6/1/2023 8:55 AM, Simon Horman wrote:
> + Daniil Tatianin <d-tatianin@yandex-team.ru>, Andrew Lunn <andrew@lunn.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@broadcom.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

>>   
>> +	memset(&cur_wol, 0, sizeof(struct ethtool_wolinfo));
>> +	cur_wol.cmd = ETHTOOL_GWOL;
>> +	dev->ethtool_ops->get_wol(dev, &cur_wol);
>> +
>>   	if (copy_from_user(&wol, useraddr, sizeof(wol)))
>>   		return -EFAULT;
>>   
>> +	if (wol.wolopts & ~cur_wol.supported)
>> +		return -EOPNOTSUPP;
>> +
>> +	if (wol.wolopts == cur_wol.wolopts)
>> +		return 0;
>> +
>>   	ret = dev->ethtool_ops->set_wol(dev, &wol);
>>   	if (ret)
>>   		return ret;

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