1/* 2 * linux/can/skb.h 3 * 4 * Definitions for the CAN network socket buffer 5 * 6 * Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net> 7 * 8 */ 9 10#ifndef _CAN_SKB_H 11#define _CAN_SKB_H 12 13#include <linux/types.h> 14#include <linux/skbuff.h> 15#include <linux/can.h> 16#include <net/sock.h> 17 18/* 19 * The struct can_skb_priv is used to transport additional information along 20 * with the stored struct can(fd)_frame that can not be contained in existing 21 * struct sk_buff elements. 22 * N.B. that this information must not be modified in cloned CAN sk_buffs. 23 * To modify the CAN frame content or the struct can_skb_priv content 24 * skb_copy() needs to be used instead of skb_clone(). 25 */ 26 27/** 28 * struct can_skb_priv - private additional data inside CAN sk_buffs 29 * @ifindex: ifindex of the first interface the CAN frame appeared on 30 * @cf: align to the following CAN frame at skb->data 31 */ 32struct can_skb_priv { 33 int ifindex; 34 struct can_frame cf[0]; 35}; 36 37static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb) 38{ 39 return (struct can_skb_priv *)(skb->head); 40} 41 42static inline void can_skb_reserve(struct sk_buff *skb) 43{ 44 skb_reserve(skb, sizeof(struct can_skb_priv)); 45} 46 47static inline void can_skb_destructor(struct sk_buff *skb) 48{ 49 sock_put(skb->sk); 50} 51 52static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk) 53{ 54 if (sk) { 55 sock_hold(sk); 56 skb->destructor = can_skb_destructor; 57 skb->sk = sk; 58 } 59} 60 61/* 62 * returns an unshared skb owned by the original sock to be echo'ed back 63 */ 64static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb) 65{ 66 if (skb_shared(skb)) { 67 struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC); 68 69 if (likely(nskb)) { 70 can_skb_set_owner(nskb, skb->sk); 71 consume_skb(skb); 72 return nskb; 73 } else { 74 kfree_skb(skb); 75 return NULL; 76 } 77 } 78 79 /* we can assume to have an unshared skb with proper owner */ 80 return skb; 81} 82 83#endif /* !_CAN_SKB_H */ 84