netdev - Re: [PATCH net] ethtool: netlink: add missing netdev_features

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Message-ID: <20201107152312.727b2e68@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Sat, 7 Nov 2020 15:23:12 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Alexander Lobakin <alobakin@...me>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Michal Kubecek <mkubecek@...e.cz>,
        Maxim Mikityanskiy <maximmi@...lanox.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] ethtool: netlink: add missing
 netdev_features_change() call

On Thu, 05 Nov 2020 16:26:58 +0000 Alexander Lobakin wrote:
> After updating userspace Ethtool from 5.7 to 5.9, I noticed that
> NETDEV_FEAT_CHANGE is no more raised when changing netdev features
> through Ethtool.
> That's because the old Ethtool ioctl interface always calls
> netdev_features_change() at the end of user request processing to
> inform the kernel that our netdevice has some features changed, but
> the new Netlink interface does not. Instead, it just notifies itself
> with ETHTOOL_MSG_FEATURES_NTF.
> Replace this ethtool_notify() call with netdev_features_change(), so
> the kernel will be aware of any features changes, just like in case
> with the ioctl interface. This does not omit Ethtool notifications,
> as Ethtool itself listens to NETDEV_FEAT_CHANGE and drops
> ETHTOOL_MSG_FEATURES_NTF on it
> (net/ethtool/netlink.c:ethnl_netdev_event()).
> 
> Fixes: 0980bfcd6954 ("ethtool: set netdev features with FEATURES_SET request")
> Signed-off-by: Alexander Lobakin <alobakin@...me>

LGTM, one nit below

> diff --git a/net/ethtool/features.c b/net/ethtool/features.c
> index 8ee4cdbd6b82..38f526f2125d 100644
> --- a/net/ethtool/features.c
> +++ b/net/ethtool/features.c
> @@ -279,8 +279,9 @@ int ethnl_set_features(struct sk_buff *skb, struct genl_info *info)
>  					  wanted_diff_mask, new_active,
>  					  active_diff_mask, compact);
>  	}
> +

I think the reply and notification are purposefully grouped, please
drop this extra new line.

>  	if (mod)
> -		ethtool_notify(dev, ETHTOOL_MSG_FEATURES_NTF, NULL);
> +		netdev_features_change(dev);
>  
>  out_rtnl:
>  	rtnl_unlock();