On Mon, Aug 17, 2020 at 04:34:07PM +0300, Maxim Mikityanskiy wrote:
> The legacy ethtool userspace tool shows an error when no features could
> be changed. It's useful to have a netlink reply to be able to show this
> error when __netdev_update_features wasn't called, for example:
>
> 1. ethtool -k eth0
> large-receive-offload: off
> 2. ethtool -K eth0 rx-fcs on
> 3. ethtool -K eth0 lro on
> Could not change any device features
> rx-lro: off [requested on]
> 4. ethtool -K eth0 lro on
> # The output should be the same, but without this patch the kernel
> # doesn't send the reply, and ethtool is unable to detect the error.
>
> This commit makes ethtool-netlink always return a reply when requested,
> and it still avoids unnecessary calls to __netdev_update_features if the
> wanted features haven't changed.
>
> Fixes: 0980bfcd6954 ("ethtool: set netdev features with FEATURES_SET request")
> Signed-off-by: Maxim Mikityanskiy <[email protected]>Reviewed-by: Michal Kubecek <[email protected]> > --- > net/ethtool/features.c | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) > > diff --git a/net/ethtool/features.c b/net/ethtool/features.c > index 6b288bfd7678..495635f152ba 100644 > --- a/net/ethtool/features.c > +++ b/net/ethtool/features.c > @@ -268,14 +268,11 @@ int ethnl_set_features(struct sk_buff *skb, struct > genl_info *info) > bitmap_and(req_wanted, req_wanted, req_mask, NETDEV_FEATURE_COUNT); > bitmap_andnot(new_wanted, old_wanted, req_mask, NETDEV_FEATURE_COUNT); > bitmap_or(req_wanted, new_wanted, req_wanted, NETDEV_FEATURE_COUNT); > - if (bitmap_equal(req_wanted, old_wanted, NETDEV_FEATURE_COUNT)) { > - ret = 0; > - goto out_rtnl; > + if (!bitmap_equal(req_wanted, old_wanted, NETDEV_FEATURE_COUNT)) { > + dev->wanted_features &= ~dev->hw_features; > + dev->wanted_features |= ethnl_bitmap_to_features(req_wanted) & > dev->hw_features; > + __netdev_update_features(dev); > } > - > - dev->wanted_features &= ~dev->hw_features; > - dev->wanted_features |= ethnl_bitmap_to_features(req_wanted) & > dev->hw_features; > - __netdev_update_features(dev); > ethnl_features_to_bitmap(new_active, dev->features); > mod = !bitmap_equal(old_active, new_active, NETDEV_FEATURE_COUNT); We could also move these last two lines to the branch where __netdev_update_features() is actually called and replace them with bitmap_copy(new_active, old_active, NETDEV_FEATURE_COUNT); mod = false; otherwise. But it's probably not worth complicating the code. Michal
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