net: usb: cdc-ncm: check for filtering capability

If the decice does not support filtering, filtering
must not be used and all packets delivered for the
upper layers to sort.

Signed-off-by: Oliver Neukum <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/usb/cdc_ncm.c

···
 		}
 	}
 
+	if (ctx->func_desc)
+		ctx->filtering_supported = !!(ctx->func_desc->bmNetworkCapabilities
+			& USB_CDC_NCM_NCAP_ETH_FILTER);
+
 	iface_no = ctx->data->cur_altsetting->desc.bInterfaceNumber;
 
 	/* Device-specific flags */
···
 	}
 }
 
+static void cdc_ncm_update_filter(struct usbnet *dev)
+{
+	struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
+
+	if (ctx->filtering_supported)
+		usbnet_cdc_update_filter(dev);
+}
+
 static const struct driver_info cdc_ncm_info = {
 	.description = "CDC NCM (NO ZLP)",
 	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
···
 	.status = cdc_ncm_status,
 	.rx_fixup = cdc_ncm_rx_fixup,
 	.tx_fixup = cdc_ncm_tx_fixup,
-	.set_rx_mode = usbnet_cdc_update_filter,
+	.set_rx_mode = cdc_ncm_update_filter,
 };
 
 /* Same as cdc_ncm_info, but with FLAG_SEND_ZLP  */
···
 	.status = cdc_ncm_status,
 	.rx_fixup = cdc_ncm_rx_fixup,
 	.tx_fixup = cdc_ncm_tx_fixup,
-	.set_rx_mode = usbnet_cdc_update_filter,
+	.set_rx_mode = cdc_ncm_update_filter,
 };
 
 /* Same as cdc_ncm_info, but with FLAG_SEND_ZLP */
···
 	.status = cdc_ncm_status,
 	.rx_fixup = cdc_ncm_rx_fixup,
 	.tx_fixup = cdc_ncm_tx_fixup,
-	.set_rx_mode = usbnet_cdc_update_filter,
+	.set_rx_mode = cdc_ncm_update_filter,
 };
 
 /* Same as wwan_info, but with FLAG_NOARP  */
···
 	.status = cdc_ncm_status,
 	.rx_fixup = cdc_ncm_rx_fixup,
 	.tx_fixup = cdc_ncm_tx_fixup,
-	.set_rx_mode = usbnet_cdc_update_filter,
+	.set_rx_mode = cdc_ncm_update_filter,
 };
 
 static const struct usb_device_id cdc_devs[] = {

include/linux/usb/cdc_ncm.h

···
 	u32 timer_interval;
 	u32 max_ndp_size;
 	u8 is_ndp16;
+	u8 filtering_supported;
 	union {
 		struct usb_cdc_ncm_ndp16 *delayed_ndp16;
 		struct usb_cdc_ncm_ndp32 *delayed_ndp32;