From 156c2bb9f88065c8da78814f98fde665a5cbb527 Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Thu, 17 Jan 2013 18:43:39 +0100 Subject: can: add private data space for CAN sk_buffs The struct can_skb_priv is used to transport additional information along with the stored struct can(fd)_frame that can not be contained in existing struct sk_buff elements. can_skb_priv is located in the skb headroom, which does not touch the existing CAN sk_buff usage with skb->data and skb->len, so that even out-of-tree CAN drivers can be used without changes. Btw. out-of-tree CAN drivers without can_skb_priv in the sk_buff headroom would not support features based on can_skb_priv. The can_skb_priv->ifindex contains the first interface where the CAN frame appeared on the local host. Unfortunately skb->skb_iif can not be used as this value is overwritten in every netif_receive_skb() call. Signed-off-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde --- include/linux/can/skb.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 include/linux/can/skb.h (limited to 'include/linux/can') diff --git a/include/linux/can/skb.h b/include/linux/can/skb.h new file mode 100644 index 000000000000..4b0f24d3a878 --- /dev/null +++ b/include/linux/can/skb.h @@ -0,0 +1,35 @@ +/* + * linux/can/skb.h + * + * Definitions for the CAN network socket buffer + * + * Copyright (C) 2012 Oliver Hartkopp + * + */ + +#ifndef CAN_SKB_H +#define CAN_SKB_H + +#include +#include + +/* + * The struct can_skb_priv is used to transport additional information along + * with the stored struct can(fd)_frame that can not be contained in existing + * struct sk_buff elements. + * N.B. that this information must not be modified in cloned CAN sk_buffs. + * To modify the CAN frame content or the struct can_skb_priv content + * skb_copy() needs to be used instead of skb_clone(). + */ + +/** + * struct can_skb_priv - private additional data inside CAN sk_buffs + * @ifindex: ifindex of the first interface the CAN frame appeared on + * @cf: align to the following CAN frame at skb->data + */ +struct can_skb_priv { + int ifindex; + struct can_frame cf[0]; +}; + +#endif /* CAN_SKB_H */ -- cgit v1.2.3