Re: [PATCH rdma-next] IB/IPoIB: Forward MTU change to driver below

[Yuval Shaia <yuval.shaia-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On Tue, May 23, 2017 at 12:24:28PM +0300, Leon Romanovsky wrote:
> On Tue, May 23, 2017 at 11:56:45AM +0300, Yuval Shaia wrote:
> > On Tue, May 23, 2017 at 11:42:52AM +0300, Leon Romanovsky wrote:
> > > From: Erez Shitrit <erezsh-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > >
> > > This patch checks if there is a driver below that
> >
> > Is it "below" or "upper" in the driver hierarchy?
> 
> The part which  close to the HW. I called it "below".
> 
> >
> > > needs to be updated on the new MTU and calls it
> > > accordingly.
> > >
> > > Signed-off-by: Erez Shitrit <erezsh-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > > Reviewed by: Alex Vesker <valex-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > > Signed-off-by: Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> > > ---
> > >  drivers/infiniband/ulp/ipoib/ipoib_main.c | 19 +++++++++++++++++--
> > >  1 file changed, 17 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
> > > index 2869d1adb1de..28068140800c 100644
> > > --- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
> > > +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
> > > @@ -233,6 +233,7 @@ static netdev_features_t ipoib_fix_features(struct net_device *dev, netdev_featu
> > >  static int ipoib_change_mtu(struct net_device *dev, int new_mtu)
> > >  {
> > >  	struct ipoib_dev_priv *priv = ipoib_priv(dev);
> > > +	int ret = 0;
> > >
> > >  	/* dev->mtu > 2K ==> connected mode */
> > >  	if (ipoib_cm_admin_enabled(dev)) {
> > > @@ -256,9 +257,23 @@ static int ipoib_change_mtu(struct net_device *dev, int new_mtu)
> > >  		ipoib_dbg(priv, "MTU must be smaller than the underlying "
> > >  				"link layer MTU - 4 (%u)\n", priv->mcast_mtu);
> > >
> > > -	dev->mtu = min(priv->mcast_mtu, priv->admin_mtu);
> > > +	new_mtu = min(priv->mcast_mtu, priv->admin_mtu);
> > >
> > > -	return 0;
> > > +	if (priv->rn_ops->ndo_change_mtu) {
> > > +		bool carrier_status = netif_carrier_ok(dev);
> > > +
> > > +		netif_carrier_off(dev);
> > > +
> > > +		/* notify lower level on the real mtu */
> > > +		ret = priv->rn_ops->ndo_change_mtu(dev, new_mtu);
> > > +
> > > +		if (carrier_status)
> > > +			netif_carrier_on(dev);
> > > +	} else {
> > > +		dev->mtu = new_mtu;
> > > +	}
> >
> > So we don't want dev->mtu to be updated if driver was registered?
> 
> It is updated in ndo_change_mtu call. See nes. cxgb3/4 and mlx4/5 as an
> example.
> 
> >
> > > +
> > > +	return ret;
> > >  }

Reviewed-by: Yuval Shaia <yuval.shaia-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>

> > >
> > >  /* Called with an RCU read lock taken */
> > > --
> > > 2.12.2
> > >
> > > --
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