ACK / APPLIED[bionic]: [PATCH][SRU][B, A, X, T] virtio-net: Fix operstate for virtio when no VIRTIO_NET_F_STATUS

[Seth Forshee]

On Thu, Apr 05, 2018 at 02:12:22PM -0400, Eric Desrochers wrote:
> From: Jay Vosburgh <jay.vosburgh at canonical.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1761534
> 
> The operstate update logic will leave an interface in the
> default UNKNOWN operstate if the interface carrier state never changes
> from the default carrier up state set at creation.  This includes the
> case of an explicit call to netif_carrier_on, as the carrier on to on
> transition has no effect on operstate.
> 
> 	This affects virtio-net for the case that the virtio peer does
> not support VIRTIO_NET_F_STATUS (the feature that provides carrier state
> updates).  Without this feature, the virtio specification states that
> "the link should be assumed active," so, logically, the operstate should
> be UP instead of UNKNOWN.  This has impact on user space applications
> that use the operstate to make availability decisions for the interface.
> 
> 	Resolve this by changing the virtio probe logic slightly to call
> netif_carrier_off for both the "with" and "without" VIRTIO_NET_F_STATUS
> cases, and then the existing call to netif_carrier_on for the "without"
> case will cause an operstate transition.
> 
> Cc: "Michael S. Tsirkin" <mst at redhat.com>
> Cc: Jason Wang <jasowang at redhat.com>
> Cc: Ben Hutchings <ben at decadent.org.uk>
> Signed-off-by: Jay Vosburgh <jay.vosburgh at canonical.com>
> Acked-by: Michael S. Tsirkin <mst at redhat.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry-picked from commit bda7fab54828bbef2164bb23c0f6b1a7d05cc718)
> Signed-off-by: Eric Desrochers <eric.desrochers at canonical.com>

Acked-by: Seth Forshee <seth.forshee at canonical.com>

Applied to bionic/master-next, thanks!