[PATCH] ibmveth: Add a proper check for the availability of the checksum features

[David Miller]

From: Thomas Huth <thuth at redhat.com>
Date: Tue, 24 Jan 2017 07:28:41 +0100

> When using the ibmveth driver in a KVM/QEMU based VM, it currently
> always prints out a scary error message like this when it is started:
> 
>  ibmveth 71000003 (unregistered net_device): unable to change
>  checksum offload settings. 1 rc=-2 ret_attr=71000003
> 
> This happens because the driver always tries to enable the checksum
> offloading without checking for the availability of this feature first.
> QEMU does not support checksum offloading for the spapr-vlan device,
> thus we always get the error message here.
> According to the LoPAPR specification, the "ibm,illan-options" property
> of the corresponding device tree node should be checked first to see
> whether the H_ILLAN_ATTRIUBTES hypercall and thus the checksum offloading
> feature is available. Thus let's do this in the ibmveth driver, too, so
> that the error message is really only limited to cases where something
> goes wrong, and does not occur if the feature is just missing.
> 
> Signed-off-by: Thomas Huth <thuth at redhat.com>

Applied.