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/*
* 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 the socket has already been closed by user space, the
* refcount may already be 0 (and the socket will be freed
* after the last TX skb has been freed). So only increase
* socket refcount if the refcount is > 0.
*/
if (sk && atomic_inc_not_zero(&sk->sk_refcnt)) {
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)
{
struct sk_buff *nskb;
nskb = skb_clone(skb, GFP_ATOMIC);
if (unlikely(!nskb)) {
kfree_skb(skb);
return NULL;
}
can_skb_set_owner(nskb, skb->sk);
consume_skb(skb);
return nskb;
}
#endif /* !_CAN_SKB_H */
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