xref: /openbmc/linux/include/linux/can/skb.h (revision fb08cba1)
1 /* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
2 /*
3  * linux/can/skb.h
4  *
5  * Definitions for the CAN network socket buffer
6  *
7  * Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>
8  *
9  */
10 
11 #ifndef _CAN_SKB_H
12 #define _CAN_SKB_H
13 
14 #include <linux/types.h>
15 #include <linux/skbuff.h>
16 #include <linux/can.h>
17 #include <net/sock.h>
18 
19 void can_flush_echo_skb(struct net_device *dev);
20 int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
21 		     unsigned int idx, unsigned int frame_len);
22 struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
23 				   unsigned int *len_ptr,
24 				   unsigned int *frame_len_ptr);
25 unsigned int __must_check can_get_echo_skb(struct net_device *dev,
26 					   unsigned int idx,
27 					   unsigned int *frame_len_ptr);
28 void can_free_echo_skb(struct net_device *dev, unsigned int idx,
29 		       unsigned int *frame_len_ptr);
30 struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
31 struct sk_buff *alloc_canfd_skb(struct net_device *dev,
32 				struct canfd_frame **cfd);
33 struct sk_buff *alloc_canxl_skb(struct net_device *dev,
34 				struct canxl_frame **cxl,
35 				unsigned int data_len);
36 struct sk_buff *alloc_can_err_skb(struct net_device *dev,
37 				  struct can_frame **cf);
38 bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb);
39 
40 /*
41  * The struct can_skb_priv is used to transport additional information along
42  * with the stored struct can(fd)_frame that can not be contained in existing
43  * struct sk_buff elements.
44  * N.B. that this information must not be modified in cloned CAN sk_buffs.
45  * To modify the CAN frame content or the struct can_skb_priv content
46  * skb_copy() needs to be used instead of skb_clone().
47  */
48 
49 /**
50  * struct can_skb_priv - private additional data inside CAN sk_buffs
51  * @ifindex:	ifindex of the first interface the CAN frame appeared on
52  * @skbcnt:	atomic counter to have an unique id together with skb pointer
53  * @frame_len:	length of CAN frame in data link layer
54  * @cf:		align to the following CAN frame at skb->data
55  */
56 struct can_skb_priv {
57 	int ifindex;
58 	int skbcnt;
59 	unsigned int frame_len;
60 	struct can_frame cf[];
61 };
62 
can_skb_prv(struct sk_buff * skb)63 static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
64 {
65 	return (struct can_skb_priv *)(skb->head);
66 }
67 
can_skb_reserve(struct sk_buff * skb)68 static inline void can_skb_reserve(struct sk_buff *skb)
69 {
70 	skb_reserve(skb, sizeof(struct can_skb_priv));
71 }
72 
can_skb_set_owner(struct sk_buff * skb,struct sock * sk)73 static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
74 {
75 	/* If the socket has already been closed by user space, the
76 	 * refcount may already be 0 (and the socket will be freed
77 	 * after the last TX skb has been freed). So only increase
78 	 * socket refcount if the refcount is > 0.
79 	 */
80 	if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) {
81 		skb->destructor = sock_efree;
82 		skb->sk = sk;
83 	}
84 }
85 
86 /*
87  * returns an unshared skb owned by the original sock to be echo'ed back
88  */
can_create_echo_skb(struct sk_buff * skb)89 static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
90 {
91 	struct sk_buff *nskb;
92 
93 	nskb = skb_clone(skb, GFP_ATOMIC);
94 	if (unlikely(!nskb)) {
95 		kfree_skb(skb);
96 		return NULL;
97 	}
98 
99 	can_skb_set_owner(nskb, skb->sk);
100 	consume_skb(skb);
101 	return nskb;
102 }
103 
can_is_can_skb(const struct sk_buff * skb)104 static inline bool can_is_can_skb(const struct sk_buff *skb)
105 {
106 	struct can_frame *cf = (struct can_frame *)skb->data;
107 
108 	/* the CAN specific type of skb is identified by its data length */
109 	return (skb->len == CAN_MTU && cf->len <= CAN_MAX_DLEN);
110 }
111 
can_is_canfd_skb(const struct sk_buff * skb)112 static inline bool can_is_canfd_skb(const struct sk_buff *skb)
113 {
114 	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
115 
116 	/* the CAN specific type of skb is identified by its data length */
117 	return (skb->len == CANFD_MTU && cfd->len <= CANFD_MAX_DLEN);
118 }
119 
can_is_canxl_skb(const struct sk_buff * skb)120 static inline bool can_is_canxl_skb(const struct sk_buff *skb)
121 {
122 	const struct canxl_frame *cxl = (struct canxl_frame *)skb->data;
123 
124 	if (skb->len < CANXL_HDR_SIZE + CANXL_MIN_DLEN || skb->len > CANXL_MTU)
125 		return false;
126 
127 	/* this also checks valid CAN XL data length boundaries */
128 	if (skb->len != CANXL_HDR_SIZE + cxl->len)
129 		return false;
130 
131 	return cxl->flags & CANXL_XLF;
132 }
133 
134 /* get length element value from can[|fd|xl]_frame structure */
can_skb_get_len_val(struct sk_buff * skb)135 static inline unsigned int can_skb_get_len_val(struct sk_buff *skb)
136 {
137 	const struct canxl_frame *cxl = (struct canxl_frame *)skb->data;
138 	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
139 
140 	if (can_is_canxl_skb(skb))
141 		return cxl->len;
142 
143 	return cfd->len;
144 }
145 
146 /* get needed data length inside CAN frame for all frame types (RTR aware) */
can_skb_get_data_len(struct sk_buff * skb)147 static inline unsigned int can_skb_get_data_len(struct sk_buff *skb)
148 {
149 	unsigned int len = can_skb_get_len_val(skb);
150 	const struct can_frame *cf = (struct can_frame *)skb->data;
151 
152 	/* RTR frames have an actual length of zero */
153 	if (can_is_can_skb(skb) && cf->can_id & CAN_RTR_FLAG)
154 		return 0;
155 
156 	return len;
157 }
158 
159 #endif /* !_CAN_SKB_H */
160