remove checking interface's name in check_rx_frame

The CAN-FD flag inference logic in check_rx_frame was gated on can_name
== "vcan0". This was added as a workaround for virtual CAN interfaces
(vcan), which do not distinguish between CAN and CAN-FD frames at the
socket level, i.e., all frames arrive as CanAnyFrame::Normal regardless of
their actual type.

However, the interface name check is unnecessary. Classic CAN frames can
never exceed 8 bytes, so the condition `res_len > 8` is already
sufficient to infer a CAN-FD frame when the feature has been negotiated.
This holds for all interface types:

- vcan: frames arrive without the FD flag, but res_len > 8 detects them
- Real CAN-FD hardware: the FD flag is already set by process_frame, so
  the additional |= is redundant but harmless
- Real classic CAN hardware: frames never exceed 8 bytes, so the
  condition is never triggered

Removing the name check also fixes the limitation of only supporting an
interface named exactly "vcan0", which excluded vcan1, vcan2, etc.

Signed-off-by: Matias Ezequiel Vara Larsen <mvaralar@redhat.com>

Author: MatiasVara

vhost-device-can/src/vhu_can.rs

@@ -272,16 +272,12 @@ impl VhostUserCanBackend {
             can_rx.flags = (can_rx.flags.to_native() | VIRTIO_CAN_FLAGS_RTR).into();
         }
 
-        // Treat Vcan interface as CANFD if MTU is set to 64 bytes.
-        //
-        // Vcan can not be configured as CANFD interface, but it is
-        // possible to configure its MTU to 64 bytes. So if a messages
-        // bigger than 8 bytes is being received we consider it as
-        // CANFD message.
-        let can_name = self.controller.read().unwrap().can_name.clone();
-        if self.check_features(VIRTIO_CAN_F_CAN_FD) && res_len > 8 && can_name == "vcan0" {
+        // Classic CAN frames cannot exceed 8 bytes. If CAN-FD has been
+        // negotiated and the frame length is > 8, treat it as a CAN-FD
+        // frame. This also covers virtual interfaces (vcan) which do not
+        // distinguish between CAN and CAN-FD at the socket level.
+        if self.check_features(VIRTIO_CAN_F_CAN_FD) && res_len > 8 {
             res_flags |= CAN_FRMF_TYPE_FD;
-            warn!("\n\n\nCANFD VCAN0\n\n");
         }
 
         // Check if CAN/FD length is out-of-range (based on negotiated features)