can: remove CAN FD compatibility for CAN 2.0 sockets
In commit e2d265d3b5
(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>
This commit is contained in:
parent
4b5b82274a
commit
821047c405
2 changed files with 5 additions and 27 deletions
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@ -554,12 +554,6 @@ solution for a couple of reasons:
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not specified in the struct can_frame and therefore it is only valid in
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CANFD_MTU sized CAN FD frames.
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As long as the payload length is <=8 the received CAN frames from CAN FD
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capable CAN devices can be received and read by legacy sockets too. When
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user-generated CAN FD frames have a payload length <=8 these can be send
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by legacy CAN network interfaces too. Sending CAN FD frames with payload
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length > 8 to a legacy CAN network interface returns an -EMSGSIZE error.
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Implementation hint for new CAN applications:
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To build a CAN FD aware application use struct canfd_frame as basic CAN
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@ -121,13 +121,9 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
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if (!ro->recv_own_msgs && oskb->sk == sk)
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return;
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/* do not pass frames with DLC > 8 to a legacy socket */
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if (!ro->fd_frames) {
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struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
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if (unlikely(cfd->len > CAN_MAX_DLEN))
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return;
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}
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/* do not pass non-CAN2.0 frames to a legacy socket */
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if (!ro->fd_frames && oskb->len != CAN_MTU)
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return;
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/* clone the given skb to be able to enqueue it into the rcv queue */
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skb = skb_clone(oskb, GFP_ATOMIC);
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@ -738,9 +734,7 @@ static int raw_recvmsg(struct kiocb *iocb, struct socket *sock,
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struct msghdr *msg, size_t size, int flags)
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{
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struct sock *sk = sock->sk;
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struct raw_sock *ro = raw_sk(sk);
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struct sk_buff *skb;
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int rxmtu;
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int err = 0;
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int noblock;
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@ -751,20 +745,10 @@ static int raw_recvmsg(struct kiocb *iocb, struct socket *sock,
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if (!skb)
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return err;
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/*
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* when serving a legacy socket the DLC <= 8 is already checked inside
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* raw_rcv(). Now check if we need to pass a canfd_frame to a legacy
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* socket and cut the possible CANFD_MTU/CAN_MTU length to CAN_MTU
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*/
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if (!ro->fd_frames)
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rxmtu = CAN_MTU;
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else
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rxmtu = skb->len;
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if (size < rxmtu)
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if (size < skb->len)
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msg->msg_flags |= MSG_TRUNC;
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else
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size = rxmtu;
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size = skb->len;
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err = memcpy_toiovec(msg->msg_iov, skb->data, size);
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if (err < 0) {
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