/*
|
* linux/can/skb.h
|
*
|
* Definitions for the CAN network socket buffer
|
*
|
* Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>
|
*
|
*/
|
|
#ifndef _CAN_SKB_H
|
#define _CAN_SKB_H
|
|
#include <linux/types.h>
|
#include <linux/skbuff.h>
|
#include <linux/can.h>
|
#include <net/sock.h>
|
|
/*
|
* 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
|
* @skbcnt: atomic counter to have an unique id together with skb pointer
|
* @cf: align to the following CAN frame at skb->data
|
*/
|
struct can_skb_priv {
|
int ifindex;
|
int skbcnt;
|
struct can_frame cf[0];
|
};
|
|
static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
|
{
|
return (struct can_skb_priv *)(skb->head);
|
}
|
|
static inline void can_skb_reserve(struct sk_buff *skb)
|
{
|
skb_reserve(skb, sizeof(struct can_skb_priv));
|
}
|
|
static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
|
{
|
if (sk) {
|
sock_hold(sk);
|
skb->destructor = sock_efree;
|
skb->sk = sk;
|
}
|
}
|
|
/*
|
* returns an unshared skb owned by the original sock to be echo'ed back
|
*/
|
static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
|
{
|
if (skb_shared(skb)) {
|
struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
|
|
if (likely(nskb)) {
|
can_skb_set_owner(nskb, skb->sk);
|
consume_skb(skb);
|
return nskb;
|
} else {
|
kfree_skb(skb);
|
return NULL;
|
}
|
}
|
|
/* we can assume to have an unshared skb with proper owner */
|
return skb;
|
}
|
|
#endif /* !_CAN_SKB_H */
|
