4.16-stable review patch. If anyone has any objections, please let me know.
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From: Jay Vosburgh jay.vosburgh@canonical.com
[ Upstream commit bda7fab54828bbef2164bb23c0f6b1a7d05cc718 ]
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@redhat.com Cc: Jason Wang jasowang@redhat.com Cc: Ben Hutchings ben@decadent.org.uk Signed-off-by: Jay Vosburgh jay.vosburgh@canonical.com Acked-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/virtio_net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2874,8 +2874,8 @@ static int virtnet_probe(struct virtio_d
/* Assume link up if device can't report link status, otherwise get link status from config. */ + netif_carrier_off(dev); if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) { - netif_carrier_off(dev); schedule_work(&vi->config_work); } else { vi->status = VIRTIO_NET_S_LINK_UP;