can: do not increase rx_bytes statistics for RTR frames

The actual payload length of the CAN Remote Transmission Request (RTR)
frames is always 0, i.e. no payload is transmitted on the wire.
However, those RTR frames still use the DLC to indicate the length of
the requested frame.

As such, net_device_stats::rx_bytes should not be increased for the
RTR frames.

This patch fixes all the CAN drivers.

Link: https://lore.kernel.org/all/20211207121531.42941-5-mailhol.vincent@wanadoo.fr
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: Chandrasekar Ramakrishnan <rcsekar@samsung.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Yasushi SHOJI <yashi@spacecubics.com>
Cc: Appana Durga Kedareswara rao <appana.durga.rao@xilinx.com>
Cc: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Stephane Grosjean <s.grosjean@peak-system.com>
Tested-by: Jimmy Assarsson <extja@kvaser.com> # kvaser
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Acked-by: Stefan Mätje <stefan.maetje@esd.eu> # esd_usb2
Tested-by: Stefan Mätje <stefan.maetje@esd.eu> # esd_usb2
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

3 files changed, 14 insertions, 11 deletions

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c
index a59417827168..17dc178f555b 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb.c
@@ -677,15 +677,16 @@ static int pcan_usb_decode_data(struct pcan_usb_msg_context *mc, u8 status_len)
 		/* Ignore next byte (client private id) if SRR bit is set */
 		if (can_id_flags & PCAN_USB_TX_SRR)
 			mc->ptr++;
+
+		/* update statistics */
+		mc->netdev->stats.rx_bytes += cf->len;
 	}
+	mc->netdev->stats.rx_packets++;
 
 	/* convert timestamp into kernel time */
 	hwts = skb_hwtstamps(skb);
 	peak_usb_get_ts_time(&mc->pdev->time_ref, mc->ts16, &hwts->hwtstamp);
 
-	/* update statistics */
-	mc->netdev->stats.rx_packets++;
-	mc->netdev->stats.rx_bytes += cf->len;
 	/* push the skb */
 	netif_rx(skb);
 
diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
index 185f5a98d217..65487ec33566 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
@@ -507,13 +507,13 @@ static int pcan_usb_fd_decode_canmsg(struct pcan_usb_fd_if *usb_if,
 	if (rx_msg_flags & PUCAN_MSG_EXT_ID)
 		cfd->can_id |= CAN_EFF_FLAG;
 
-	if (rx_msg_flags & PUCAN_MSG_RTR)
+	if (rx_msg_flags & PUCAN_MSG_RTR) {
 		cfd->can_id |= CAN_RTR_FLAG;
-	else
+	} else {
 		memcpy(cfd->data, rm->d, cfd->len);
-
+		netdev->stats.rx_bytes += cfd->len;
+	}
 	netdev->stats.rx_packets++;
-	netdev->stats.rx_bytes += cfd->len;
 
 	peak_usb_netif_rx_64(skb, le32_to_cpu(rm->ts_low),
 			     le32_to_cpu(rm->ts_high));
diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_pro.c b/drivers/net/can/usb/peak_usb/pcan_usb_pro.c
index f6d19879bf40..ebe087f258e3 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb_pro.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_pro.c
@@ -536,17 +536,19 @@ static int pcan_usb_pro_handle_canmsg(struct pcan_usb_pro_interface *usb_if,
 	if (rx->flags & PCAN_USBPRO_EXT)
 		can_frame->can_id |= CAN_EFF_FLAG;
 
-	if (rx->flags & PCAN_USBPRO_RTR)
+	if (rx->flags & PCAN_USBPRO_RTR) {
 		can_frame->can_id |= CAN_RTR_FLAG;
-	else
+	} else {
 		memcpy(can_frame->data, rx->data, can_frame->len);
 
+		netdev->stats.rx_bytes += can_frame->len;
+	}
+	netdev->stats.rx_packets++;
+
 	hwts = skb_hwtstamps(skb);
 	peak_usb_get_ts_time(&usb_if->time_ref, le32_to_cpu(rx->ts32),
 			     &hwts->hwtstamp);
 
-	netdev->stats.rx_packets++;
-	netdev->stats.rx_bytes += can_frame->len;
 	netif_rx(skb);
 
 	return 0;