linux/can/skb.h

0001 /* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
0002 /*
0003  * linux/can/skb.h
0004  *
0005  * Definitions for the CAN network socket buffer
0006  *
0007  * Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>
0008  *
0009  */
0010
0011 #ifndef _CAN_SKB_H
0012 #define _CAN_SKB_H
0013
0014 #include <linux/types.h>
0015 #include <linux/skbuff.h>
0016 #include <linux/can.h>
0017 #include <net/sock.h>
0018
0019 void can_flush_echo_skb(struct net_device *dev);
0020 int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
0021              unsigned int idx, unsigned int frame_len);
0022 struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
0023                    u8 *len_ptr, unsigned int *frame_len_ptr);
0024 unsigned int __must_check can_get_echo_skb(struct net_device *dev,
0025                        unsigned int idx,
0026                        unsigned int *frame_len_ptr);
0027 void can_free_echo_skb(struct net_device *dev, unsigned int idx,
0028                unsigned int *frame_len_ptr);
0029 struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
0030 struct sk_buff *alloc_canfd_skb(struct net_device *dev,
0031                 struct canfd_frame **cfd);
0032 struct sk_buff *alloc_can_err_skb(struct net_device *dev,
0033                   struct can_frame **cf);
0034 bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb);
0035
0036 /*
0037  * The struct can_skb_priv is used to transport additional information along
0038  * with the stored struct can(fd)_frame that can not be contained in existing
0039  * struct sk_buff elements.
0040  * N.B. that this information must not be modified in cloned CAN sk_buffs.
0041  * To modify the CAN frame content or the struct can_skb_priv content
0042  * skb_copy() needs to be used instead of skb_clone().
0043  */
0044
0045 /**
0046  * struct can_skb_priv - private additional data inside CAN sk_buffs
0047  * @ifindex:    ifindex of the first interface the CAN frame appeared on
0048  * @skbcnt: atomic counter to have an unique id together with skb pointer
0049  * @frame_len:  length of CAN frame in data link layer
0050  * @cf:     align to the following CAN frame at skb->data
0051  */
0052 struct can_skb_priv {
0053     int ifindex;
0054     int skbcnt;
0055     unsigned int frame_len;
0056     struct can_frame cf[];
0057 };
0058
0059 static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
0060 {
0061     return (struct can_skb_priv *)(skb->head);
0062 }
0063
0064 static inline void can_skb_reserve(struct sk_buff *skb)
0065 {
0066     skb_reserve(skb, sizeof(struct can_skb_priv));
0067 }
0068
0069 static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
0070 {
0071     /* If the socket has already been closed by user space, the
0072      * refcount may already be 0 (and the socket will be freed
0073      * after the last TX skb has been freed). So only increase
0074      * socket refcount if the refcount is > 0.
0075      */
0076     if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) {
0077         skb->destructor = sock_efree;
0078         skb->sk = sk;
0079     }
0080 }
0081
0082 /*
0083  * returns an unshared skb owned by the original sock to be echo'ed back
0084  */
0085 static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
0086 {
0087     struct sk_buff *nskb;
0088
0089     nskb = skb_clone(skb, GFP_ATOMIC);
0090     if (unlikely(!nskb)) {
0091         kfree_skb(skb);
0092         return NULL;
0093     }
0094
0095     can_skb_set_owner(nskb, skb->sk);
0096     consume_skb(skb);
0097     return nskb;
0098 }
0099
0100 static inline bool can_is_canfd_skb(const struct sk_buff *skb)
0101 {
0102     /* the CAN specific type of skb is identified by its data length */
0103     return skb->len == CANFD_MTU;
0104 }
0105
0106 #endif /* !_CAN_SKB_H */