Hi Michal,
Thanks for reviewing,
and sorry for late reply.
On Thu, May 21, 2020 at 09:23:42PM +0200, Michal Kubecek wrote:
> On Fri, May 22, 2020 at 01:59:13AM +0800, Chen Yu wrote:
> > Currently the ethtool shows that WOL(Wake On Lan) is enabled
> > even if the device wakeup ability has been disabled via sysfs:
> > cat /sys/devices/pci0000:00/0000:00:1f.6/power/wakeup
> > disabled
> >
> > ethtool eno1
> > ...
> > Wake-on: g
> >
> > Fix this in ethtool to check if the user has explicitly disabled the
> > wake up ability for this device.
>
> Wouldn't this lead to rather unexpected and inconsistent behaviour when
> the wakeup is disabled? As you don't touch the set_wol handler, I assume
> it will still allow setting enabled modes as usual so that you get e.g.
>
> ethtool -s eth0 wol g # no error or warning, returns 0
> ethtool eth0 # reports no modes enabled
>
> The first command would set the enabled wol modes but that would be
> hidden from user and even the netlink notification would claim something
> different. Another exampe (with kernel and ethtool >= 5.6):
>
> ethtool -s eth0 wol g
> ethtool -s eth0 wol +m
>
> resulting in "mg" if device wakeup is enabled but "m" when it's disabled
> (but the latter would be hidden from user and only revealed when you
> enable the device wakeup).
>
I've tested ethtool v5.6 on top of kernel v5.7-rc6, it looks like
the scenario you described will not happen as it will not allow
the user to enable the wol options with device wakeup disabled,
not sure if I missed something:
/sys/devices/pci0000:00/0000:00:1f.6/power# echo disabled > wakeup
ethtool -s eno1 wol g
netlink error: cannot enable unsupported WoL mode (offset 36)
netlink error: Invalid argument
I've not digged into the code too much, but according to
ethhl_set_wol(), it will first get the current wol options
via dev->ethtool_ops->get_wol(), and both the wolopts and
wol.supported are 0 when device wake up are disabled. Then
ethnl_update_bitset32 might manipulate on wolopts and
make it non-zero each is controdict with the precondition that
no opts should be enabled due to 0 wol.supported.
> This is a general problem discussed recently for EEE and pause
> autonegotiation: if setting A can be effectively used only when B is
> enabled, should we hide actual setting of A from userspace when B is
> disabled or even reset the value of A whenever B gets toggled or rather
> allow setting A and B independently? AFAICS the consensus seemed to be
> that A should be allowed to be set and queried independently of the
> value of B.
But then there would be an inconsistence between A and B. I was thinking
if there's a way to align them in kernel space and maintain the difference in user space?
Thanks,
Chenyu
>
> Michal
>
> > Fixes: 6ff68026f475 ("e1000e: Use device_set_wakeup_enable")
> > Reported-by: Len Brown <len.brown@xxxxxxxxx>
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > Cc: <Stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
> > ---
> > drivers/net/ethernet/intel/e1000e/ethtool.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/intel/e1000e/ethtool.c b/drivers/net/ethernet/intel/e1000e/ethtool.c
> > index 1d47e2503072..0cccd823ff24 100644
> > --- a/drivers/net/ethernet/intel/e1000e/ethtool.c
> > +++ b/drivers/net/ethernet/intel/e1000e/ethtool.c
> > @@ -1891,7 +1891,7 @@ static void e1000_get_wol(struct net_device *netdev,
> > wol->wolopts = 0;
> >
> > if (!(adapter->flags & FLAG_HAS_WOL) ||
> > - !device_can_wakeup(&adapter->pdev->dev))
> > + !device_may_wakeup(&adapter->pdev->dev))
> > return;
> >
> > wol->supported = WAKE_UCAST | WAKE_MCAST |
> > --
> > 2.17.1
> >
