/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
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/*
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* linux/can/skb.h
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*
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* Definitions for the CAN network socket buffer
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*
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* Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>
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*
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*/
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#ifndef _CAN_SKB_H
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#define _CAN_SKB_H
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#include <linux/types.h>
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#include <linux/skbuff.h>
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#include <linux/can.h>
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#include <net/sock.h>
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/*
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* The struct can_skb_priv is used to transport additional information along
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* with the stored struct can(fd)_frame that can not be contained in existing
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* struct sk_buff elements.
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* N.B. that this information must not be modified in cloned CAN sk_buffs.
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* To modify the CAN frame content or the struct can_skb_priv content
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* skb_copy() needs to be used instead of skb_clone().
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*/
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/**
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* struct can_skb_priv - private additional data inside CAN sk_buffs
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* @ifindex: ifindex of the first interface the CAN frame appeared on
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* @skbcnt: atomic counter to have an unique id together with skb pointer
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* @cf: align to the following CAN frame at skb->data
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*/
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struct can_skb_priv {
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int ifindex;
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int skbcnt;
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struct can_frame cf[];
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};
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static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
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{
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return (struct can_skb_priv *)(skb->head);
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}
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static inline void can_skb_reserve(struct sk_buff *skb)
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{
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skb_reserve(skb, sizeof(struct can_skb_priv));
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}
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static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
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{
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/* If the socket has already been closed by user space, the
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* refcount may already be 0 (and the socket will be freed
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* after the last TX skb has been freed). So only increase
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* socket refcount if the refcount is > 0.
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*/
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if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) {
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skb->destructor = sock_efree;
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skb->sk = sk;
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}
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}
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/*
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* returns an unshared skb owned by the original sock to be echo'ed back
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*/
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static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
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{
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struct sk_buff *nskb;
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nskb = skb_clone(skb, GFP_ATOMIC);
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if (unlikely(!nskb)) {
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kfree_skb(skb);
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return NULL;
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}
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can_skb_set_owner(nskb, skb->sk);
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consume_skb(skb);
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return nskb;
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}
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#endif /* !_CAN_SKB_H */
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