include/linux/can/skb.h

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This source file includes following definitions.

can_skb_prv
can_skb_reserve
can_skb_destructor
can_skb_set_owner
can_create_echo_skb

/*
 * 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
 * @cf:         align to the following CAN frame at skb->data
 */
struct can_skb_priv {
        int ifindex;
        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_destructor(struct sk_buff *skb)
{
        sock_put(skb->sk);
}

static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
{
        if (sk) {
                sock_hold(sk);
                skb->destructor = can_skb_destructor;
                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 */

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root/include/linux/can/skb.h

DEFINITIONS