On Wed. 24 Nov. 2021 à 06:01, Oliver Hartkopp [off-list ref] wrote:

On 23.11.21 12:53, Vincent Mailhol wrote:

quoted

CAN error skb is an interface specific to socket CAN. The CAN error
skb does not correspond to any actual CAN frame sent on the wire. Only
an error flag and a delimiter are transmitted when an error occurs
(c.f. ISO 11898-1 section 10.4.4.2 "Error flag").

For this reason, it makes no sense to increment the rx_packets and
rx_bytes fields of struct net_device_stats because no actual payload
were transmitted on the wire.

(..)

quoted

diff --git a/drivers/net/can/dev/rx-offload.c b/drivers/net/can/dev/rx-offload.c
index 37b0cc65237b..bb47e9a49240 100644
--- a/drivers/net/can/dev/rx-offload.c
+++ b/drivers/net/can/dev/rx-offload.c

@@ -54,8 +54,10 @@ static int can_rx_offload_napi_poll(struct napi_struct *napi, int quota)
              struct can_frame *cf = (struct can_frame *)skb->data;

              work_done++;
-             stats->rx_packets++;
-             stats->rx_bytes += cf->len;
+             if (!(cf->can_id & CAN_ERR_MASK)) {

This looks wrong.

And it is.

Did you think of CAN_ERR_FLAG ??

Yes, I will fix this in v2.

quoted

+                     stats->rx_packets++;
+                     stats->rx_bytes += cf->len;
+             }
              netif_receive_skb(skb);

(..)

quoted

diff --git a/drivers/net/can/usb/ucan.c b/drivers/net/can/usb/ucan.c
index 1679cbe45ded..d582c39fc8d0 100644
--- a/drivers/net/can/usb/ucan.c
+++ b/drivers/net/can/usb/ucan.c

@@ -621,8 +621,10 @@ static void ucan_rx_can_msg(struct ucan_priv *up, struct ucan_message_in *m)
              memcpy(cf->data, m->msg.can_msg.data, cf->len);

      /* don't count error frames as real packets */
-     stats->rx_packets++;
-     stats->rx_bytes += cf->len;
+     if (!(cf->can_id & CAN_ERR_FLAG)) {

Ah, here we are :-)

Thank you!