[linux-2.6-block.git] / net / caif / cfpkt_skbuff.c

/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:	Sjur Brendeland
 * License terms: GNU General Public License (GPL) version 2
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__

#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/hardirq.h>
#include <linux/export.h>
#include <net/caif/cfpkt.h>

#define PKT_PREFIX  48
#define PKT_POSTFIX 2
#define PKT_LEN_WHEN_EXTENDING 128
#define PKT_ERROR(pkt, errmsg)		   \
do {					   \
	cfpkt_priv(pkt)->erronous = true;  \
	skb_reset_tail_pointer(&pkt->skb); \
	pr_warn(errmsg);		   \
} while (0)

struct cfpktq {
	struct sk_buff_head head;
	atomic_t count;
	/* Lock protects count updates */
	spinlock_t lock;
};

/*
 * net/caif/ is generic and does not
 * understand SKB, so we do this typecast
 */
struct cfpkt {
	struct sk_buff skb;
};

/* Private data inside SKB */
struct cfpkt_priv_data {
	struct dev_info dev_info;
	bool erronous;
};

static inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
{
	return (struct cfpkt_priv_data *) pkt->skb.cb;
}

static inline bool is_erronous(struct cfpkt *pkt)
{
	return cfpkt_priv(pkt)->erronous;
}

static inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
{
	return &pkt->skb;
}

static inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
{
	return (struct cfpkt *) skb;
}

struct cfpkt *cfpkt_fromnative(enum caif_direction dir, void *nativepkt)
{
	struct cfpkt *pkt = skb_to_pkt(nativepkt);
	cfpkt_priv(pkt)->erronous = false;
	return pkt;
}
EXPORT_SYMBOL(cfpkt_fromnative);

void *cfpkt_tonative(struct cfpkt *pkt)
{
	return (void *) pkt;
}
EXPORT_SYMBOL(cfpkt_tonative);

static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
{
	struct sk_buff *skb;

	if (likely(in_interrupt()))
		skb = alloc_skb(len + pfx, GFP_ATOMIC);
	else
		skb = alloc_skb(len + pfx, GFP_KERNEL);

	if (unlikely(skb == NULL))
		return NULL;

	skb_reserve(skb, pfx);
	return skb_to_pkt(skb);
}

inline struct cfpkt *cfpkt_create(u16 len)
{
	return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
}

void cfpkt_destroy(struct cfpkt *pkt)
{
	struct sk_buff *skb = pkt_to_skb(pkt);
	kfree_skb(skb);
}

inline bool cfpkt_more(struct cfpkt *pkt)
{
	struct sk_buff *skb = pkt_to_skb(pkt);
	return skb->len > 0;
}

int cfpkt_peek_head(struct cfpkt *pkt, void *data, u16 len)
{
	struct sk_buff *skb = pkt_to_skb(pkt);
	if (skb_headlen(skb) >= len) {
		memcpy(data, skb->data, len);
		return 0;
	}
	return !cfpkt_extr_head(pkt, data, len) &&
	    !cfpkt_add_head(pkt, data, len);
}

int cfpkt_extr_head(struct cfpkt *pkt, void *data, u16 len)
{
	struct sk_buff *skb = pkt_to_skb(pkt);
	u8 *from;
	if (unlikely(is_erronous(pkt)))
		return -EPROTO;

	if (unlikely(len > skb->len)) {
		PKT_ERROR(pkt, "read beyond end of packet\n");
		return -EPROTO;
	}

	if (unlikely(len > skb_headlen(skb))) {
		if (unlikely(skb_linearize(skb) != 0)) {
			PKT_ERROR(pkt, "linearize failed\n");
			return -EPROTO;
		}
	}
	from = skb_pull(skb, len);
	from -= len;
	if (data)
		memcpy(data, from, len);
	return 0;
}
EXPORT_SYMBOL(cfpkt_extr_head);

int cfpkt_extr_trail(struct cfpkt *pkt, void *dta, u16 len)
{
	struct sk_buff *skb = pkt_to_skb(pkt);
	u8 *data = dta;
	u8 *from;
	if (unlikely(is_erronous(pkt)))
		return -EPROTO;

	if (unlikely(skb_linearize(skb) != 0)) {
		PKT_ERROR(pkt, "linearize failed\n");
		return -EPROTO;
	}
	if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
		PKT_ERROR(pkt, "read beyond end of packet\n");
		return -EPROTO;
	}
	from = skb_tail_pointer(skb) - len;
	skb_trim(skb, skb->len - len);
	memcpy(data, from, len);
	return 0;
}

int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
{
	return cfpkt_add_body(pkt, NULL, len);
}

int cfpkt_add_body(struct cfpkt *pkt, const void *data, u16 len)
{
	struct sk_buff *skb = pkt_to_skb(pkt);
	struct sk_buff *lastskb;
	u8 *to;
	u16 addlen = 0;


	if (unlikely(is_erronous(pkt)))
		return -EPROTO;

	lastskb = skb;

	/* Check whether we need to add space at the tail */
	if (unlikely(skb_tailroom(skb) < len)) {
		if (likely(len < PKT_LEN_WHEN_EXTENDING))
			addlen = PKT_LEN_WHEN_EXTENDING;
		else
			addlen = len;
	}

	/* Check whether we need to change the SKB before writing to the tail */
	if (unlikely((addlen > 0) || skb_cloned(skb) || skb_shared(skb))) {

		/* Make sure data is writable */
		if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
			PKT_ERROR(pkt, "cow failed\n");
			return -EPROTO;
		}
	}

	/* All set to put the last SKB and optionally write data there. */
	to = pskb_put(skb, lastskb, len);
	if (likely(data))
		memcpy(to, data, len);
	return 0;
}

inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
{
	return cfpkt_add_body(pkt, &data, 1);
}

int cfpkt_add_head(struct cfpkt *pkt, const void *data2, u16 len)
{
	struct sk_buff *skb = pkt_to_skb(pkt);
	struct sk_buff *lastskb;
	u8 *to;
	const u8 *data = data2;
	int ret;
	if (unlikely(is_erronous(pkt)))
		return -EPROTO;
	if (unlikely(skb_headroom(skb) < len)) {
		PKT_ERROR(pkt, "no headroom\n");
		return -EPROTO;
	}

	/* Make sure data is writable */
	ret = skb_cow_data(skb, 0, &lastskb);
	if (unlikely(ret < 0)) {
		PKT_ERROR(pkt, "cow failed\n");
		return ret;
	}

	to = skb_push(skb, len);
	memcpy(to, data, len);
	return 0;
}
EXPORT_SYMBOL(cfpkt_add_head);

inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
{
	return cfpkt_add_body(pkt, data, len);
}

inline u16 cfpkt_getlen(struct cfpkt *pkt)
{
	struct sk_buff *skb = pkt_to_skb(pkt);
	return skb->len;
}

int cfpkt_iterate(struct cfpkt *pkt,
		  u16 (*iter_func)(u16, void *, u16),
		  u16 data)
{
	/*
	 * Don't care about the performance hit of linearizing,
	 * Checksum should not be used on high-speed interfaces anyway.
	 */
	if (unlikely(is_erronous(pkt)))
		return -EPROTO;
	if (unlikely(skb_linearize(&pkt->skb) != 0)) {
		PKT_ERROR(pkt, "linearize failed\n");
		return -EPROTO;
	}
	return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
}

int cfpkt_setlen(struct cfpkt *pkt, u16 len)
{
	struct sk_buff *skb = pkt_to_skb(pkt);


	if (unlikely(is_erronous(pkt)))
		return -EPROTO;

	if (likely(len <= skb->len)) {
		if (unlikely(skb->data_len))
			___pskb_trim(skb, len);
		else
			skb_trim(skb, len);

			return cfpkt_getlen(pkt);
	}

	/* Need to expand SKB */
	if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
		PKT_ERROR(pkt, "skb_pad_trail failed\n");

	return cfpkt_getlen(pkt);
}

struct cfpkt *cfpkt_append(struct cfpkt *dstpkt,
			   struct cfpkt *addpkt,
			   u16 expectlen)
{
	struct sk_buff *dst = pkt_to_skb(dstpkt);
	struct sk_buff *add = pkt_to_skb(addpkt);
	u16 addlen = skb_headlen(add);
	u16 neededtailspace;
	struct sk_buff *tmp;
	u16 dstlen;
	u16 createlen;
	if (unlikely(is_erronous(dstpkt) || is_erronous(addpkt))) {
		return dstpkt;
	}
	if (expectlen > addlen)
		neededtailspace = expectlen;
	else
		neededtailspace = addlen;

	if (dst->tail + neededtailspace > dst->end) {
		/* Create a dumplicate of 'dst' with more tail space */
		struct cfpkt *tmppkt;
		dstlen = skb_headlen(dst);
		createlen = dstlen + neededtailspace;
		tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
		if (tmppkt == NULL)
			return NULL;
		tmp = pkt_to_skb(tmppkt);
		skb_set_tail_pointer(tmp, dstlen);
		tmp->len = dstlen;
		memcpy(tmp->data, dst->data, dstlen);
		cfpkt_destroy(dstpkt);
		dst = tmp;
	}
	memcpy(skb_tail_pointer(dst), add->data, skb_headlen(add));
	cfpkt_destroy(addpkt);
	dst->tail += addlen;
	dst->len += addlen;
	return skb_to_pkt(dst);
}

struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
{
	struct sk_buff *skb2;
	struct sk_buff *skb = pkt_to_skb(pkt);
	struct cfpkt *tmppkt;
	u8 *split = skb->data + pos;
	u16 len2nd = skb_tail_pointer(skb) - split;

	if (unlikely(is_erronous(pkt)))
		return NULL;

	if (skb->data + pos > skb_tail_pointer(skb)) {
		PKT_ERROR(pkt, "trying to split beyond end of packet\n");
		return NULL;
	}

	/* Create a new packet for the second part of the data */
	tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
				  PKT_PREFIX);
	if (tmppkt == NULL)
		return NULL;
	skb2 = pkt_to_skb(tmppkt);


	if (skb2 == NULL)
		return NULL;

	/* Reduce the length of the original packet */
	skb_set_tail_pointer(skb, pos);
	skb->len = pos;

	memcpy(skb2->data, split, len2nd);
	skb2->tail += len2nd;
	skb2->len += len2nd;
	skb2->priority = skb->priority;
	return skb_to_pkt(skb2);
}

bool cfpkt_erroneous(struct cfpkt *pkt)
{
	return cfpkt_priv(pkt)->erronous;
}

struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
{
	return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
}
EXPORT_SYMBOL(cfpkt_info);

void cfpkt_set_prio(struct cfpkt *pkt, int prio)
{
	pkt_to_skb(pkt)->priority = prio;
}
EXPORT_SYMBOL(cfpkt_set_prio);
Commit	Line	Data
15c9ac0c SB	1	/*
15c9ac0c SB	2	* Copyright (C) ST-Ericsson AB 2010
26ee65e6	3	* Author: Sjur Brendeland
15c9ac0c SB	4	* License terms: GNU General Public License (GPL) version 2
	5	*/
	6
b31fa5ba JP	7	#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
b31fa5ba JP	8
15c9ac0c SB	9	#include <linux/string.h>
	10	#include <linux/skbuff.h>
	11	#include <linux/hardirq.h>
bc3b2d7f	12	#include <linux/export.h>
15c9ac0c SB	13	#include <net/caif/cfpkt.h>
15c9ac0c SB	14
24e263ad	15	#define PKT_PREFIX 48
2aa40aef	16	#define PKT_POSTFIX 2
15c9ac0c	17	#define PKT_LEN_WHEN_EXTENDING 128
b31fa5ba JP	18	#define PKT_ERROR(pkt, errmsg) \
	19	do { \
	20	cfpkt_priv(pkt)->erronous = true; \
	21	skb_reset_tail_pointer(&pkt->skb); \
	22	pr_warn(errmsg); \
	23	} while (0)
15c9ac0c SB	24
	25	struct cfpktq {
	26	struct sk_buff_head head;
	27	atomic_t count;
	28	/* Lock protects count updates */
	29	spinlock_t lock;
	30	};
	31
	32	/*
	33	* net/caif/ is generic and does not
	34	* understand SKB, so we do this typecast
	35	*/
	36	struct cfpkt {
	37	struct sk_buff skb;
	38	};
	39
	40	/* Private data inside SKB */
	41	struct cfpkt_priv_data {
	42	struct dev_info dev_info;
	43	bool erronous;
	44	};
	45
73d6ac63	46	static inline struct cfpkt_priv_data cfpkt_priv(struct cfpkt pkt)
15c9ac0c SB	47	{
	48	return (struct cfpkt_priv_data *) pkt->skb.cb;
	49	}
	50
73d6ac63	51	static inline bool is_erronous(struct cfpkt *pkt)
15c9ac0c SB	52	{
	53	return cfpkt_priv(pkt)->erronous;
	54	}
	55
73d6ac63	56	static inline struct sk_buff pkt_to_skb(struct cfpkt pkt)
15c9ac0c SB	57	{
	58	return &pkt->skb;
	59	}
	60
73d6ac63	61	static inline struct cfpkt skb_to_pkt(struct sk_buff skb)
15c9ac0c SB	62	{
	63	return (struct cfpkt *) skb;
	64	}
	65
15c9ac0c SB	66	struct cfpkt cfpkt_fromnative(enum caif_direction dir, void nativepkt)
	67	{
	68	struct cfpkt *pkt = skb_to_pkt(nativepkt);
	69	cfpkt_priv(pkt)->erronous = false;
	70	return pkt;
	71	}
	72	EXPORT_SYMBOL(cfpkt_fromnative);
	73
	74	void cfpkt_tonative(struct cfpkt pkt)
	75	{
	76	return (void *) pkt;
	77	}
	78	EXPORT_SYMBOL(cfpkt_tonative);
	79
	80	static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
	81	{
	82	struct sk_buff *skb;
	83
	84	if (likely(in_interrupt()))
	85	skb = alloc_skb(len + pfx, GFP_ATOMIC);
	86	else
	87	skb = alloc_skb(len + pfx, GFP_KERNEL);
	88
	89	if (unlikely(skb == NULL))
	90	return NULL;
	91
	92	skb_reserve(skb, pfx);
	93	return skb_to_pkt(skb);
	94	}
	95
	96	inline struct cfpkt *cfpkt_create(u16 len)
	97	{
	98	return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
	99	}
15c9ac0c SB	100
	101	void cfpkt_destroy(struct cfpkt *pkt)
	102	{
	103	struct sk_buff *skb = pkt_to_skb(pkt);
	104	kfree_skb(skb);
	105	}
3f874adc	106
15c9ac0c SB	107	inline bool cfpkt_more(struct cfpkt *pkt)
	108	{
	109	struct sk_buff *skb = pkt_to_skb(pkt);
	110	return skb->len > 0;
	111	}
3f874adc	112
15c9ac0c SB	113	int cfpkt_peek_head(struct cfpkt pkt, void data, u16 len)
	114	{
	115	struct sk_buff *skb = pkt_to_skb(pkt);
	116	if (skb_headlen(skb) >= len) {
	117	memcpy(data, skb->data, len);
	118	return 0;
	119	}
	120	return !cfpkt_extr_head(pkt, data, len) &&
	121	!cfpkt_add_head(pkt, data, len);
	122	}
15c9ac0c SB	123
	124	int cfpkt_extr_head(struct cfpkt pkt, void data, u16 len)
	125	{
	126	struct sk_buff *skb = pkt_to_skb(pkt);
	127	u8 *from;
	128	if (unlikely(is_erronous(pkt)))
	129	return -EPROTO;
	130
	131	if (unlikely(len > skb->len)) {
b31fa5ba	132	PKT_ERROR(pkt, "read beyond end of packet\n");
15c9ac0c SB	133	return -EPROTO;
	134	}
	135
	136	if (unlikely(len > skb_headlen(skb))) {
	137	if (unlikely(skb_linearize(skb) != 0)) {
b31fa5ba	138	PKT_ERROR(pkt, "linearize failed\n");
15c9ac0c SB	139	return -EPROTO;
	140	}
	141	}
	142	from = skb_pull(skb, len);
	143	from -= len;
200c5a3b	144	if (data)
200c5a3b	145	memcpy(data, from, len);
15c9ac0c SB	146	return 0;
15c9ac0c SB	147	}
7ad65bf6	148	EXPORT_SYMBOL(cfpkt_extr_head);
15c9ac0c SB	149
	150	int cfpkt_extr_trail(struct cfpkt pkt, void dta, u16 len)
	151	{
	152	struct sk_buff *skb = pkt_to_skb(pkt);
	153	u8 *data = dta;
	154	u8 *from;
	155	if (unlikely(is_erronous(pkt)))
	156	return -EPROTO;
	157
	158	if (unlikely(skb_linearize(skb) != 0)) {
b31fa5ba	159	PKT_ERROR(pkt, "linearize failed\n");
15c9ac0c SB	160	return -EPROTO;
	161	}
	162	if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
b31fa5ba	163	PKT_ERROR(pkt, "read beyond end of packet\n");
15c9ac0c SB	164	return -EPROTO;
	165	}
	166	from = skb_tail_pointer(skb) - len;
	167	skb_trim(skb, skb->len - len);
	168	memcpy(data, from, len);
	169	return 0;
	170	}
3f874adc	171
15c9ac0c SB	172	int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
	173	{
	174	return cfpkt_add_body(pkt, NULL, len);
	175	}
3f874adc	176
15c9ac0c SB	177	int cfpkt_add_body(struct cfpkt pkt, const void data, u16 len)
	178	{
	179	struct sk_buff *skb = pkt_to_skb(pkt);
	180	struct sk_buff *lastskb;
	181	u8 *to;
	182	u16 addlen = 0;
	183
	184
	185	if (unlikely(is_erronous(pkt)))
	186	return -EPROTO;
	187
	188	lastskb = skb;
	189
	190	/* Check whether we need to add space at the tail */
	191	if (unlikely(skb_tailroom(skb) < len)) {
	192	if (likely(len < PKT_LEN_WHEN_EXTENDING))
	193	addlen = PKT_LEN_WHEN_EXTENDING;
	194	else
	195	addlen = len;
	196	}
	197
	198	/* Check whether we need to change the SKB before writing to the tail */
	199	if (unlikely((addlen > 0) \|\| skb_cloned(skb) \|\| skb_shared(skb))) {
	200
	201	/* Make sure data is writable */
	202	if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
b31fa5ba	203	PKT_ERROR(pkt, "cow failed\n");
15c9ac0c SB	204	return -EPROTO;
15c9ac0c SB	205	}
15c9ac0c SB	206	}
	207
	208	/* All set to put the last SKB and optionally write data there. */
253c6daa	209	to = pskb_put(skb, lastskb, len);
15c9ac0c SB	210	if (likely(data))
	211	memcpy(to, data, len);
	212	return 0;
	213	}
15c9ac0c SB	214
	215	inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
	216	{
	217	return cfpkt_add_body(pkt, &data, 1);
	218	}
15c9ac0c SB	219
	220	int cfpkt_add_head(struct cfpkt pkt, const void data2, u16 len)
	221	{
	222	struct sk_buff *skb = pkt_to_skb(pkt);
	223	struct sk_buff *lastskb;
	224	u8 *to;
	225	const u8 *data = data2;
638e628a	226	int ret;
15c9ac0c SB	227	if (unlikely(is_erronous(pkt)))
	228	return -EPROTO;
	229	if (unlikely(skb_headroom(skb) < len)) {
b31fa5ba	230	PKT_ERROR(pkt, "no headroom\n");
15c9ac0c SB	231	return -EPROTO;
	232	}
	233
	234	/* Make sure data is writable */
638e628a SB	235	ret = skb_cow_data(skb, 0, &lastskb);
638e628a SB	236	if (unlikely(ret < 0)) {
b31fa5ba	237	PKT_ERROR(pkt, "cow failed\n");
638e628a	238	return ret;
15c9ac0c SB	239	}
	240
	241	to = skb_push(skb, len);
	242	memcpy(to, data, len);
	243	return 0;
	244	}
7ad65bf6	245	EXPORT_SYMBOL(cfpkt_add_head);
15c9ac0c SB	246
	247	inline int cfpkt_add_trail(struct cfpkt pkt, const void data, u16 len)
	248	{
	249	return cfpkt_add_body(pkt, data, len);
	250	}
3f874adc	251
15c9ac0c SB	252	inline u16 cfpkt_getlen(struct cfpkt *pkt)
	253	{
	254	struct sk_buff *skb = pkt_to_skb(pkt);
	255	return skb->len;
	256	}
3f874adc	257
278f7b4f DC	258	int cfpkt_iterate(struct cfpkt *pkt,
	259	u16 (iter_func)(u16, void , u16),
	260	u16 data)
15c9ac0c SB	261	{
	262	/*
	263	* Don't care about the performance hit of linearizing,
	264	* Checksum should not be used on high-speed interfaces anyway.
	265	*/
	266	if (unlikely(is_erronous(pkt)))
	267	return -EPROTO;
	268	if (unlikely(skb_linearize(&pkt->skb) != 0)) {
b31fa5ba	269	PKT_ERROR(pkt, "linearize failed\n");
15c9ac0c SB	270	return -EPROTO;
	271	}
	272	return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
	273	}
3f874adc	274
15c9ac0c SB	275	int cfpkt_setlen(struct cfpkt *pkt, u16 len)
	276	{
	277	struct sk_buff *skb = pkt_to_skb(pkt);
	278
	279
	280	if (unlikely(is_erronous(pkt)))
	281	return -EPROTO;
	282
	283	if (likely(len <= skb->len)) {
	284	if (unlikely(skb->data_len))
	285	___pskb_trim(skb, len);
	286	else
	287	skb_trim(skb, len);
	288
	289	return cfpkt_getlen(pkt);
	290	}
	291
	292	/* Need to expand SKB */
	293	if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
b31fa5ba	294	PKT_ERROR(pkt, "skb_pad_trail failed\n");
15c9ac0c SB	295
	296	return cfpkt_getlen(pkt);
	297	}
15c9ac0c	298
15c9ac0c	299	struct cfpkt cfpkt_append(struct cfpkt dstpkt,
3bffc475 SMP	300	struct cfpkt *addpkt,
3bffc475 SMP	301	u16 expectlen)
15c9ac0c SB	302	{
	303	struct sk_buff *dst = pkt_to_skb(dstpkt);
	304	struct sk_buff *add = pkt_to_skb(addpkt);
	305	u16 addlen = skb_headlen(add);
	306	u16 neededtailspace;
	307	struct sk_buff *tmp;
	308	u16 dstlen;
	309	u16 createlen;
	310	if (unlikely(is_erronous(dstpkt) \|\| is_erronous(addpkt))) {
15c9ac0c SB	311	return dstpkt;
	312	}
	313	if (expectlen > addlen)
	314	neededtailspace = expectlen;
	315	else
	316	neededtailspace = addlen;
	317
	318	if (dst->tail + neededtailspace > dst->end) {
	319	/* Create a dumplicate of 'dst' with more tail space */
638e628a	320	struct cfpkt *tmppkt;
15c9ac0c SB	321	dstlen = skb_headlen(dst);
15c9ac0c SB	322	createlen = dstlen + neededtailspace;
638e628a SB	323	tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
638e628a SB	324	if (tmppkt == NULL)
15c9ac0c	325	return NULL;
638e628a	326	tmp = pkt_to_skb(tmppkt);
15c9ac0c SB	327	skb_set_tail_pointer(tmp, dstlen);
	328	tmp->len = dstlen;
	329	memcpy(tmp->data, dst->data, dstlen);
	330	cfpkt_destroy(dstpkt);
	331	dst = tmp;
	332	}
	333	memcpy(skb_tail_pointer(dst), add->data, skb_headlen(add));
	334	cfpkt_destroy(addpkt);
	335	dst->tail += addlen;
	336	dst->len += addlen;
	337	return skb_to_pkt(dst);
	338	}
15c9ac0c SB	339
	340	struct cfpkt cfpkt_split(struct cfpkt pkt, u16 pos)
	341	{
	342	struct sk_buff *skb2;
	343	struct sk_buff *skb = pkt_to_skb(pkt);
638e628a	344	struct cfpkt *tmppkt;
15c9ac0c SB	345	u8 *split = skb->data + pos;
	346	u16 len2nd = skb_tail_pointer(skb) - split;
	347
	348	if (unlikely(is_erronous(pkt)))
	349	return NULL;
	350
	351	if (skb->data + pos > skb_tail_pointer(skb)) {
b31fa5ba	352	PKT_ERROR(pkt, "trying to split beyond end of packet\n");
15c9ac0c SB	353	return NULL;
	354	}
	355
	356	/* Create a new packet for the second part of the data */
638e628a SB	357	tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
	358	PKT_PREFIX);
	359	if (tmppkt == NULL)
	360	return NULL;
	361	skb2 = pkt_to_skb(tmppkt);
	362
15c9ac0c SB	363
	364	if (skb2 == NULL)
	365	return NULL;
	366
	367	/* Reduce the length of the original packet */
	368	skb_set_tail_pointer(skb, pos);
	369	skb->len = pos;
	370
	371	memcpy(skb2->data, split, len2nd);
	372	skb2->tail += len2nd;
	373	skb2->len += len2nd;
44764812	374	skb2->priority = skb->priority;
15c9ac0c SB	375	return skb_to_pkt(skb2);
15c9ac0c SB	376	}
15c9ac0c	377
73d6ac63	378	bool cfpkt_erroneous(struct cfpkt *pkt)
15c9ac0c SB	379	{
	380	return cfpkt_priv(pkt)->erronous;
	381	}
15c9ac0c SB	382
	383	struct caif_payload_info cfpkt_info(struct cfpkt pkt)
	384	{
	385	return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
	386	}
7ad65bf6	387	EXPORT_SYMBOL(cfpkt_info);
44764812 DT	388
	389	void cfpkt_set_prio(struct cfpkt *pkt, int prio)
	390	{
	391	pkt_to_skb(pkt)->priority = prio;
	392	}
	393	EXPORT_SYMBOL(cfpkt_set_prio);