netdev - RE: [net-next] vxlan: Advertise SCTP checksum offloads

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Date:	Tue, 29 Apr 2014 16:10:10 +0000
From:	"Rose, Gregory V" <gregory.v.rose@...el.com>
To:	Ben Hutchings <ben@...adent.org.uk>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"Gasparakis, Joseph" <joseph.gasparakis@...el.com>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"gospo@...hat.com" <gospo@...hat.com>,
	"sassmann@...hat.com" <sassmann@...hat.com>
Subject: RE: [net-next] vxlan: Advertise SCTP checksum offloads


> -----Original Message-----
> From: Ben Hutchings [mailto:ben@...adent.org.uk]
> Sent: Tuesday, April 29, 2014 5:39 AM
> To: Kirsher, Jeffrey T
> Cc: davem@...emloft.net; Rose, Gregory V; netdev@...r.kernel.org;
> gospo@...hat.com; sassmann@...hat.com
> Subject: Re: [net-next] vxlan: Advertise SCTP checksum offloads
> 
> On Mon, 2014-04-28 at 12:52 -0700, Jeff Kirsher wrote:
> > From: Greg Rose <gregory.v.rose@...el.com>
> >
> > Some HW can offload encapsulated SCTP checksums.  Advertise the
> > capability for such cases.
> 
> Don't we need a software fallback on the output path before doing this?

I believe that the vxlan driver will compare offload features with the lower device hw_enc_feature flags and if the HW doesn't have the offload then it won't be advertised to the sctp driver.  In that case the sctp driver will do its own checksumming.  At least that is the behavior I saw.

I'm adding Joseph Gasparakis.  He might have a better answer.

- Greg

> 
> Ben.
> 
> > Signed-off-by: Greg Rose <gregory.v.rose@...el.com>
> > Acked-by: Joseph Gasparakis <joseph.gasparakis@...el.com>
> > Acked-by: Shannon Nelson <shannon.nelson@...el.com>
> > Tested-by: Jeff Pieper <jeffrey.e.pieper@...el.com>
> > Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
> > ---
> >  drivers/net/vxlan.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index
> > 1dfee9a..988208f 100644
> > --- a/drivers/net/vxlan.c
> > +++ b/drivers/net/vxlan.c
> > @@ -2293,6 +2293,7 @@ static void vxlan_setup(struct net_device *dev)
> >  	dev->features	|= NETIF_F_SG | NETIF_F_HW_CSUM;
> >  	dev->features   |= NETIF_F_RXCSUM;
> >  	dev->features   |= NETIF_F_GSO_SOFTWARE;
> > +	dev->features   |= NETIF_F_SCTP_CSUM;
> >
> >  	dev->vlan_features = dev->features;
> >  	dev->features |= NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX;
> 
> --
> Ben Hutchings
> Q.  Which is the greater problem in the world today, ignorance or apathy?
> A.  I don't know and I couldn't care less.