Commit 821047c4055cca833c4674f172a9d73003563eb6
Committed by
Marc Kleine-Budde
Marc Kleine-Budde
1 parent
4b5b82274a
Exists in
master
and in
16 other branches
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>
Showing 2 changed files with 5 additions and 27 deletions Side-by-side Diff
Documentation/networking/can.txt
| ... | ... | @@ -554,12 +554,6 @@ |
| 554 | 554 | not specified in the struct can_frame and therefore it is only valid in |
| 555 | 555 | CANFD_MTU sized CAN FD frames. |
| 556 | 556 | |
| 557 | - As long as the payload length is <=8 the received CAN frames from CAN FD | |
| 558 | - capable CAN devices can be received and read by legacy sockets too. When | |
| 559 | - user-generated CAN FD frames have a payload length <=8 these can be send | |
| 560 | - by legacy CAN network interfaces too. Sending CAN FD frames with payload | |
| 561 | - length > 8 to a legacy CAN network interface returns an -EMSGSIZE error. | |
| 562 | - | |
| 563 | 557 | Implementation hint for new CAN applications: |
| 564 | 558 | |
| 565 | 559 | To build a CAN FD aware application use struct canfd_frame as basic CAN |
net/can/raw.c
| ... | ... | @@ -121,14 +121,10 @@ |
| 121 | 121 | if (!ro->recv_own_msgs && oskb->sk == sk) |
| 122 | 122 | return; |
| 123 | 123 | |
| 124 | - /* do not pass frames with DLC > 8 to a legacy socket */ | |
| 125 | - if (!ro->fd_frames) { | |
| 126 | - struct canfd_frame *cfd = (struct canfd_frame *)oskb->data; | |
| 124 | + /* do not pass non-CAN2.0 frames to a legacy socket */ | |
| 125 | + if (!ro->fd_frames && oskb->len != CAN_MTU) | |
| 126 | + return; | |
| 127 | 127 | |
| 128 | - if (unlikely(cfd->len > CAN_MAX_DLEN)) | |
| 129 | - return; | |
| 130 | - } | |
| 131 | - | |
| 132 | 128 | /* clone the given skb to be able to enqueue it into the rcv queue */ |
| 133 | 129 | skb = skb_clone(oskb, GFP_ATOMIC); |
| 134 | 130 | if (!skb) |
| 135 | 131 | |
| ... | ... | @@ -738,9 +734,7 @@ |
| 738 | 734 | struct msghdr *msg, size_t size, int flags) |
| 739 | 735 | { |
| 740 | 736 | struct sock *sk = sock->sk; |
| 741 | - struct raw_sock *ro = raw_sk(sk); | |
| 742 | 737 | struct sk_buff *skb; |
| 743 | - int rxmtu; | |
| 744 | 738 | int err = 0; |
| 745 | 739 | int noblock; |
| 746 | 740 | |
| 747 | 741 | |
| ... | ... | @@ -751,20 +745,10 @@ |
| 751 | 745 | if (!skb) |
| 752 | 746 | return err; |
| 753 | 747 | |
| 754 | - /* | |
| 755 | - * when serving a legacy socket the DLC <= 8 is already checked inside | |
| 756 | - * raw_rcv(). Now check if we need to pass a canfd_frame to a legacy | |
| 757 | - * socket and cut the possible CANFD_MTU/CAN_MTU length to CAN_MTU | |
| 758 | - */ | |
| 759 | - if (!ro->fd_frames) | |
| 760 | - rxmtu = CAN_MTU; | |
| 761 | - else | |
| 762 | - rxmtu = skb->len; | |
| 763 | - | |
| 764 | - if (size < rxmtu) | |
| 748 | + if (size < skb->len) | |
| 765 | 749 | msg->msg_flags |= MSG_TRUNC; |
| 766 | 750 | else |
| 767 | - size = rxmtu; | |
| 751 | + size = skb->len; | |
| 768 | 752 | |
| 769 | 753 | err = memcpy_toiovec(msg->msg_iov, skb->data, size); |
| 770 | 754 | if (err < 0) { |