netdev - Re: [PATCH intel-next v4] i40e: allow toggling loopback mode via ndo_set

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Date:   Wed, 23 Nov 2022 09:00:38 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Alexander Lobakin <alexandr.lobakin@...el.com>
Cc:     Tirthendu Sarkar <tirthendu.sarkar@...el.com>, tirtha@...il.com,
        netdev@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
        magnus.karlsson@...el.com
Subject: Re: [PATCH intel-next v4] i40e: allow toggling loopback mode via
 ndo_set_features callback

On Tue, Nov 22, 2022 at 04:57:59PM +0100, Alexander Lobakin wrote:
> From: Leon Romanovsky <leon@...nel.org>
> Date: Tue, 22 Nov 2022 13:07:28 +0200
> 
> > On Fri, Nov 18, 2022 at 02:33:06PM +0530, Tirthendu Sarkar wrote:
> > > Add support for NETIF_F_LOOPBACK. This feature can be set via:
> > > $ ethtool -K eth0 loopback <on|off>
> > > 
> > > This sets the MAC Tx->Rx loopback.
> > > 
> > > This feature is used for the xsk selftests, and might have other uses
> > > too.
> 
> [...]
> 
> > > @@ -12960,6 +12983,9 @@ static int i40e_set_features(struct net_device *netdev,
> > >  	if (need_reset)
> > >  		i40e_do_reset(pf, I40E_PF_RESET_FLAG, true);
> > >  
> > > +	if ((features ^ netdev->features) & NETIF_F_LOOPBACK)
> > > +		return i40e_set_loopback(vsi, !!(features & NETIF_F_LOOPBACK));
> > 
> > Don't you need to disable loopback if NETIF_F_LOOPBACK was cleared?
> 
> 0 ^ 1 == 1 -> call i40e_set_loopback()
> !!(0) == 0 -> disable
> 

Nice, thanks,
Reviewed-by: Leon Romanovsky <leonro@...dia.com>