[deliverable/linux.git] / net / caif / cfpkt_skbuff.c

/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:	Sjur Brendeland/sjur.brandeland@stericsson.com
 * 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;
}

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;
		}
		/*
		 * Is the SKB non-linear after skb_cow_data()? If so, we are
		 * going to add data to the last SKB, so we need to adjust
		 * lengths of the top SKB.
		 */
		if (lastskb != skb) {
			pr_warn("Packet is non-linear\n");
			skb->len += len;
			skb->data_len += len;
		}
	}

	/* All set to put the last SKB and optionally write data there. */
	to = skb_put(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;
}


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;
}


inline u16 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;
	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;
}
Commit	Line	Data
15c9ac0c SB	1	/*
	2	* Copyright (C) ST-Ericsson AB 2010
	3	* Author: Sjur Brendeland/sjur.brandeland@stericsson.com
	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
	66
	67	struct cfpkt cfpkt_fromnative(enum caif_direction dir, void nativepkt)
	68	{
	69	struct cfpkt *pkt = skb_to_pkt(nativepkt);
	70	cfpkt_priv(pkt)->erronous = false;
	71	return pkt;
	72	}
	73	EXPORT_SYMBOL(cfpkt_fromnative);
	74
	75	void cfpkt_tonative(struct cfpkt pkt)
	76	{
	77	return (void *) pkt;
	78	}
	79	EXPORT_SYMBOL(cfpkt_tonative);
	80
	81	static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
	82	{
	83	struct sk_buff *skb;
	84
	85	if (likely(in_interrupt()))
	86	skb = alloc_skb(len + pfx, GFP_ATOMIC);
	87	else
	88	skb = alloc_skb(len + pfx, GFP_KERNEL);
	89
	90	if (unlikely(skb == NULL))
	91	return NULL;
	92
	93	skb_reserve(skb, pfx);
	94	return skb_to_pkt(skb);
	95	}
	96
	97	inline struct cfpkt *cfpkt_create(u16 len)
	98	{
	99	return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
	100	}
15c9ac0c SB	101
	102	void cfpkt_destroy(struct cfpkt *pkt)
	103	{
	104	struct sk_buff *skb = pkt_to_skb(pkt);
	105	kfree_skb(skb);
	106	}
3f874adc	107
15c9ac0c SB	108
	109	inline bool cfpkt_more(struct cfpkt *pkt)
	110	{
	111	struct sk_buff *skb = pkt_to_skb(pkt);
	112	return skb->len > 0;
	113	}
3f874adc	114
15c9ac0c SB	115
	116	int cfpkt_peek_head(struct cfpkt pkt, void data, u16 len)
	117	{
	118	struct sk_buff *skb = pkt_to_skb(pkt);
	119	if (skb_headlen(skb) >= len) {
	120	memcpy(data, skb->data, len);
	121	return 0;
	122	}
	123	return !cfpkt_extr_head(pkt, data, len) &&
	124	!cfpkt_add_head(pkt, data, len);
	125	}
15c9ac0c SB	126
	127	int cfpkt_extr_head(struct cfpkt pkt, void data, u16 len)
	128	{
	129	struct sk_buff *skb = pkt_to_skb(pkt);
	130	u8 *from;
	131	if (unlikely(is_erronous(pkt)))
	132	return -EPROTO;
	133
	134	if (unlikely(len > skb->len)) {
b31fa5ba	135	PKT_ERROR(pkt, "read beyond end of packet\n");
15c9ac0c SB	136	return -EPROTO;
	137	}
	138
	139	if (unlikely(len > skb_headlen(skb))) {
	140	if (unlikely(skb_linearize(skb) != 0)) {
b31fa5ba	141	PKT_ERROR(pkt, "linearize failed\n");
15c9ac0c SB	142	return -EPROTO;
	143	}
	144	}
	145	from = skb_pull(skb, len);
	146	from -= len;
200c5a3b	147	if (data)
200c5a3b	148	memcpy(data, from, len);
15c9ac0c SB	149	return 0;
15c9ac0c SB	150	}
15c9ac0c SB	151
	152	int cfpkt_extr_trail(struct cfpkt pkt, void dta, u16 len)
	153	{
	154	struct sk_buff *skb = pkt_to_skb(pkt);
	155	u8 *data = dta;
	156	u8 *from;
	157	if (unlikely(is_erronous(pkt)))
	158	return -EPROTO;
	159
	160	if (unlikely(skb_linearize(skb) != 0)) {
b31fa5ba	161	PKT_ERROR(pkt, "linearize failed\n");
15c9ac0c SB	162	return -EPROTO;
	163	}
	164	if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
b31fa5ba	165	PKT_ERROR(pkt, "read beyond end of packet\n");
15c9ac0c SB	166	return -EPROTO;
	167	}
	168	from = skb_tail_pointer(skb) - len;
	169	skb_trim(skb, skb->len - len);
	170	memcpy(data, from, len);
	171	return 0;
	172	}
3f874adc	173
15c9ac0c SB	174
	175	int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
	176	{
	177	return cfpkt_add_body(pkt, NULL, len);
	178	}
3f874adc	179
15c9ac0c SB	180
	181	int cfpkt_add_body(struct cfpkt pkt, const void data, u16 len)
	182	{
	183	struct sk_buff *skb = pkt_to_skb(pkt);
	184	struct sk_buff *lastskb;
	185	u8 *to;
	186	u16 addlen = 0;
	187
	188
	189	if (unlikely(is_erronous(pkt)))
	190	return -EPROTO;
	191
	192	lastskb = skb;
	193
	194	/* Check whether we need to add space at the tail */
	195	if (unlikely(skb_tailroom(skb) < len)) {
	196	if (likely(len < PKT_LEN_WHEN_EXTENDING))
	197	addlen = PKT_LEN_WHEN_EXTENDING;
	198	else
	199	addlen = len;
	200	}
	201
	202	/* Check whether we need to change the SKB before writing to the tail */
	203	if (unlikely((addlen > 0) \|\| skb_cloned(skb) \|\| skb_shared(skb))) {
	204
	205	/* Make sure data is writable */
	206	if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
b31fa5ba	207	PKT_ERROR(pkt, "cow failed\n");
15c9ac0c SB	208	return -EPROTO;
	209	}
	210	/*
	211	* Is the SKB non-linear after skb_cow_data()? If so, we are
	212	* going to add data to the last SKB, so we need to adjust
	213	* lengths of the top SKB.
	214	*/
	215	if (lastskb != skb) {
b31fa5ba	216	pr_warn("Packet is non-linear\n");
15c9ac0c SB	217	skb->len += len;
	218	skb->data_len += len;
	219	}
	220	}
	221
	222	/* All set to put the last SKB and optionally write data there. */
	223	to = skb_put(lastskb, len);
	224	if (likely(data))
	225	memcpy(to, data, len);
	226	return 0;
	227	}
15c9ac0c SB	228
	229	inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
	230	{
	231	return cfpkt_add_body(pkt, &data, 1);
	232	}
15c9ac0c SB	233
	234	int cfpkt_add_head(struct cfpkt pkt, const void data2, u16 len)
	235	{
	236	struct sk_buff *skb = pkt_to_skb(pkt);
	237	struct sk_buff *lastskb;
	238	u8 *to;
	239	const u8 *data = data2;
638e628a	240	int ret;
15c9ac0c SB	241	if (unlikely(is_erronous(pkt)))
	242	return -EPROTO;
	243	if (unlikely(skb_headroom(skb) < len)) {
b31fa5ba	244	PKT_ERROR(pkt, "no headroom\n");
15c9ac0c SB	245	return -EPROTO;
	246	}
	247
	248	/* Make sure data is writable */
638e628a SB	249	ret = skb_cow_data(skb, 0, &lastskb);
638e628a SB	250	if (unlikely(ret < 0)) {
b31fa5ba	251	PKT_ERROR(pkt, "cow failed\n");
638e628a	252	return ret;
15c9ac0c SB	253	}
	254
	255	to = skb_push(skb, len);
	256	memcpy(to, data, len);
	257	return 0;
	258	}
3f874adc	259
15c9ac0c SB	260
	261	inline int cfpkt_add_trail(struct cfpkt pkt, const void data, u16 len)
	262	{
	263	return cfpkt_add_body(pkt, data, len);
	264	}
3f874adc	265
15c9ac0c SB	266
	267	inline u16 cfpkt_getlen(struct cfpkt *pkt)
	268	{
	269	struct sk_buff *skb = pkt_to_skb(pkt);
	270	return skb->len;
	271	}
3f874adc	272
15c9ac0c SB	273
	274	inline u16 cfpkt_iterate(struct cfpkt *pkt,
	275	u16 (iter_func)(u16, void , u16),
	276	u16 data)
	277	{
	278	/*
	279	* Don't care about the performance hit of linearizing,
	280	* Checksum should not be used on high-speed interfaces anyway.
	281	*/
	282	if (unlikely(is_erronous(pkt)))
	283	return -EPROTO;
	284	if (unlikely(skb_linearize(&pkt->skb) != 0)) {
b31fa5ba	285	PKT_ERROR(pkt, "linearize failed\n");
15c9ac0c SB	286	return -EPROTO;
	287	}
	288	return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
	289	}
3f874adc	290
15c9ac0c SB	291
	292	int cfpkt_setlen(struct cfpkt *pkt, u16 len)
	293	{
	294	struct sk_buff *skb = pkt_to_skb(pkt);
	295
	296
	297	if (unlikely(is_erronous(pkt)))
	298	return -EPROTO;
	299
	300	if (likely(len <= skb->len)) {
	301	if (unlikely(skb->data_len))
	302	___pskb_trim(skb, len);
	303	else
	304	skb_trim(skb, len);
	305
	306	return cfpkt_getlen(pkt);
	307	}
	308
	309	/* Need to expand SKB */
	310	if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
b31fa5ba	311	PKT_ERROR(pkt, "skb_pad_trail failed\n");
15c9ac0c SB	312
	313	return cfpkt_getlen(pkt);
	314	}
15c9ac0c	315
15c9ac0c SB	316	struct cfpkt cfpkt_append(struct cfpkt dstpkt,
	317	struct cfpkt *addpkt,
	318	u16 expectlen)
	319	{
	320	struct sk_buff *dst = pkt_to_skb(dstpkt);
	321	struct sk_buff *add = pkt_to_skb(addpkt);
	322	u16 addlen = skb_headlen(add);
	323	u16 neededtailspace;
	324	struct sk_buff *tmp;
	325	u16 dstlen;
	326	u16 createlen;
	327	if (unlikely(is_erronous(dstpkt) \|\| is_erronous(addpkt))) {
15c9ac0c SB	328	return dstpkt;
	329	}
	330	if (expectlen > addlen)
	331	neededtailspace = expectlen;
	332	else
	333	neededtailspace = addlen;
	334
	335	if (dst->tail + neededtailspace > dst->end) {
	336	/* Create a dumplicate of 'dst' with more tail space */
638e628a	337	struct cfpkt *tmppkt;
15c9ac0c SB	338	dstlen = skb_headlen(dst);
15c9ac0c SB	339	createlen = dstlen + neededtailspace;
638e628a SB	340	tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
638e628a SB	341	if (tmppkt == NULL)
15c9ac0c	342	return NULL;
638e628a	343	tmp = pkt_to_skb(tmppkt);
15c9ac0c SB	344	skb_set_tail_pointer(tmp, dstlen);
	345	tmp->len = dstlen;
	346	memcpy(tmp->data, dst->data, dstlen);
	347	cfpkt_destroy(dstpkt);
	348	dst = tmp;
	349	}
	350	memcpy(skb_tail_pointer(dst), add->data, skb_headlen(add));
	351	cfpkt_destroy(addpkt);
	352	dst->tail += addlen;
	353	dst->len += addlen;
	354	return skb_to_pkt(dst);
	355	}
15c9ac0c SB	356
	357	struct cfpkt cfpkt_split(struct cfpkt pkt, u16 pos)
	358	{
	359	struct sk_buff *skb2;
	360	struct sk_buff *skb = pkt_to_skb(pkt);
638e628a	361	struct cfpkt *tmppkt;
15c9ac0c SB	362	u8 *split = skb->data + pos;
	363	u16 len2nd = skb_tail_pointer(skb) - split;
	364
	365	if (unlikely(is_erronous(pkt)))
	366	return NULL;
	367
	368	if (skb->data + pos > skb_tail_pointer(skb)) {
b31fa5ba	369	PKT_ERROR(pkt, "trying to split beyond end of packet\n");
15c9ac0c SB	370	return NULL;
	371	}
	372
	373	/* Create a new packet for the second part of the data */
638e628a SB	374	tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
	375	PKT_PREFIX);
	376	if (tmppkt == NULL)
	377	return NULL;
	378	skb2 = pkt_to_skb(tmppkt);
	379
15c9ac0c SB	380
	381	if (skb2 == NULL)
	382	return NULL;
	383
	384	/* Reduce the length of the original packet */
	385	skb_set_tail_pointer(skb, pos);
	386	skb->len = pos;
	387
	388	memcpy(skb2->data, split, len2nd);
	389	skb2->tail += len2nd;
	390	skb2->len += len2nd;
	391	return skb_to_pkt(skb2);
	392	}
15c9ac0c	393
73d6ac63	394	bool cfpkt_erroneous(struct cfpkt *pkt)
15c9ac0c SB	395	{
	396	return cfpkt_priv(pkt)->erronous;
	397	}
15c9ac0c SB	398
	399	struct caif_payload_info cfpkt_info(struct cfpkt pkt)
	400	{
	401	return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
	402	}