can: remove CAN FD compatibility for CAN 2.0 sockets
In commit e2d265d3b587 (canfd: add support for CAN FD in CAN_RAW sockets)
CAN FD frames with a payload length up to 8 byte are passed to legacy
sockets where the CAN FD support was not enabled by the application.
After some discussions with developers at a fair this well meant feature
leads to confusion as no clean switch for CAN / CAN FD is provided to the
application programmer. Additionally a compatibility like this for legacy
CAN_RAW sockets requires some compatibility handling for the sending, e.g.
make CAN2.0 frames a CAN FD frame with BRS at transmission time (?!?).
This will become a mess when people start to develop applications with
real CAN FD hardware. This patch reverts the bad compatibility code
together with the documentation describing the removed feature.
Acked-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/net/can/raw.c b/net/can/raw.c
index 8be757c..081e81f 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -121,13 +121,9 @@
if (!ro->recv_own_msgs && oskb->sk == sk)
return;
- /* do not pass frames with DLC > 8 to a legacy socket */
- if (!ro->fd_frames) {
- struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
-
- if (unlikely(cfd->len > CAN_MAX_DLEN))
- return;
- }
+ /* do not pass non-CAN2.0 frames to a legacy socket */
+ if (!ro->fd_frames && oskb->len != CAN_MTU)
+ return;
/* clone the given skb to be able to enqueue it into the rcv queue */
skb = skb_clone(oskb, GFP_ATOMIC);
@@ -738,9 +734,7 @@
struct msghdr *msg, size_t size, int flags)
{
struct sock *sk = sock->sk;
- struct raw_sock *ro = raw_sk(sk);
struct sk_buff *skb;
- int rxmtu;
int err = 0;
int noblock;
@@ -751,20 +745,10 @@
if (!skb)
return err;
- /*
- * when serving a legacy socket the DLC <= 8 is already checked inside
- * raw_rcv(). Now check if we need to pass a canfd_frame to a legacy
- * socket and cut the possible CANFD_MTU/CAN_MTU length to CAN_MTU
- */
- if (!ro->fd_frames)
- rxmtu = CAN_MTU;
- else
- rxmtu = skb->len;
-
- if (size < rxmtu)
+ if (size < skb->len)
msg->msg_flags |= MSG_TRUNC;
else
- size = rxmtu;
+ size = skb->len;
err = memcpy_toiovec(msg->msg_iov, skb->data, size);
if (err < 0) {