From mboxrd@z Thu Jan  1 00:00:00 1970
From: Richard Cochran <richardcochran@gmail.com>
Subject: Re: [PATCH net] vlan: also check phy_driver ts_info for vlan's real
 device
Date: Fri, 30 Mar 2018 08:21:21 -0700
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 <20180330150214.GF28244@lunn.ch>
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Cc: Hangbin Liu <liuhangbin@gmail.com>, netdev@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>
To: Andrew Lunn <andrew@lunn.ch>
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On Fri, Mar 30, 2018 at 05:02:14PM +0200, Andrew Lunn wrote:
> Would it not be better to just call ethtool_get_ts_info() on the real
> device? That would then also deal with the case that the 'real' device
> is another virtual device stacked on top of a real device.

That won't work.

The returned 'ethtool_ts_info' is on the stack of
ethtool_get_ts_info().  Both the top level and the inner call to
will call copy_to_user(), but the top level will clobber the correct
result with zeros.

Thanks,
Richard