This is a note to let you know that I've just added the patch titled
can: dev: __can_get_echo_skb(): fix real payload length return value for RTR frames
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
can-dev-__can_get_echo_skb-fix-real-payload-length-r.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8c26159ce080a722710d017eb64ca79484173be4
Author: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Date: Tue Oct 20 08:44:43 2020 +0200
can: dev: __can_get_echo_skb(): fix real payload length return value for RTR frames
[ Upstream commit ed3320cec279407a86bc4c72edc4a39eb49165ec ]
The can_get_echo_skb() function returns the number of received bytes to
be used for netdev statistics. In the case of RTR frames we get a valid
(potential non-zero) data length value which has to be passed for further
operations. But on the wire RTR frames have no payload length. Therefore
the value to be used in the statistics has to be zero for RTR frames.
Reported-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201020064443.80164-1-socketcan@xxxxxxxxxxxx
Fixes: cf5046b309b3 ("can: dev: let can_get_echo_skb() return dlc of CAN frame")
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index de3c589b1ae0e..448d1548cca39 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -486,9 +486,13 @@ __can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr)
*/
struct sk_buff *skb = priv->echo_skb[idx];
struct canfd_frame *cf = (struct canfd_frame *)skb->data;
- u8 len = cf->len;
- *len_ptr = len;
+ /* get the real payload length for netdev statistics */
+ if (cf->can_id & CAN_RTR_FLAG)
+ *len_ptr = 0;
+ else
+ *len_ptr = cf->len;
+
priv->echo_skb[idx] = NULL;
return skb;
