net: cdc_ncm/cdc_mbim: adding NCM protocol statistics

To have an idea of the effects of the protocol coalescing
it's useful to have some counters showing the different
aspects.

Due to the asymmetrical usbnet interface the netdev
rx_bytes counter has been counting real received payload,
while the tx_bytes counter has included the NCM/MBIM
framing overhead. This overhead can be many times the
payload because of the aggressive padding strategy of
this driver, and will vary a lot depending on device
and traffic.

With very few exceptions, users are only interested in
the payload size.  Having an somewhat accurate payload
byte counter is particularly important for mobile
broadband devices, which many NCM devices and of course
all MBIM devices are. Users and userspace applications
will use this counter to monitor account quotas.

Having protocol specific counters for the overhead, we are
now able to correct the tx_bytes netdev counter so that
it shows the real payload

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/usb/cdc_ncm.h b/include/linux/usb/cdc_ncm.h
index 79de6724d398..88d2d7f1820f 100644
--- a/include/linux/usb/cdc_ncm.h
+++ b/include/linux/usb/cdc_ncm.h
@@ -116,6 +116,17 @@ struct cdc_ncm_ctx {
 	u16 rx_seq;
 	u16 connected;
 	u16 min_tx_pkt;
+
+	/* statistics */
+	u32 tx_curr_frame_payload;
+	u32 tx_reason_ntb_full;
+	u32 tx_reason_ndp_full;
+	u32 tx_reason_timeout;
+	u32 tx_reason_max_datagram;
+	u64 tx_overhead;
+	u64 tx_ntbs;
+	u64 rx_overhead;
+	u64 rx_ntbs;
 };
 
 u8 cdc_ncm_select_altsetting(struct usb_interface *intf);