1/*
2 * Copyright (C) ST-Ericsson AB 2010
3 * Author:	Sjur Brendeland
4 * License terms: GNU General Public License (GPL) version 2
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
8
9#include <linux/string.h>
10#include <linux/skbuff.h>
11#include <linux/hardirq.h>
12#include <linux/export.h>
13#include <net/caif/cfpkt.h>
14
15#define PKT_PREFIX  48
16#define PKT_POSTFIX 2
17#define PKT_LEN_WHEN_EXTENDING 128
18#define PKT_ERROR(pkt, errmsg)		   \
19do {					   \
20	cfpkt_priv(pkt)->erronous = true;  \
21	skb_reset_tail_pointer(&pkt->skb); \
22	pr_warn(errmsg);		   \
23} while (0)
24
25struct 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 */
36struct cfpkt {
37	struct sk_buff skb;
38};
39
40/* Private data inside SKB */
41struct cfpkt_priv_data {
42	struct dev_info dev_info;
43	bool erronous;
44};
45
46static inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
47{
48	return (struct cfpkt_priv_data *) pkt->skb.cb;
49}
50
51static inline bool is_erronous(struct cfpkt *pkt)
52{
53	return cfpkt_priv(pkt)->erronous;
54}
55
56static inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
57{
58	return &pkt->skb;
59}
60
61static inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
62{
63	return (struct cfpkt *) skb;
64}
65
66struct 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}
72EXPORT_SYMBOL(cfpkt_fromnative);
73
74void *cfpkt_tonative(struct cfpkt *pkt)
75{
76	return (void *) pkt;
77}
78EXPORT_SYMBOL(cfpkt_tonative);
79
80static 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
96inline struct cfpkt *cfpkt_create(u16 len)
97{
98	return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
99}
100
101void cfpkt_destroy(struct cfpkt *pkt)
102{
103	struct sk_buff *skb = pkt_to_skb(pkt);
104	kfree_skb(skb);
105}
106
107inline bool cfpkt_more(struct cfpkt *pkt)
108{
109	struct sk_buff *skb = pkt_to_skb(pkt);
110	return skb->len > 0;
111}
112
113int 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}
123
124int 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)) {
132		PKT_ERROR(pkt, "read beyond end of packet\n");
133		return -EPROTO;
134	}
135
136	if (unlikely(len > skb_headlen(skb))) {
137		if (unlikely(skb_linearize(skb) != 0)) {
138			PKT_ERROR(pkt, "linearize failed\n");
139			return -EPROTO;
140		}
141	}
142	from = skb_pull(skb, len);
143	from -= len;
144	if (data)
145		memcpy(data, from, len);
146	return 0;
147}
148EXPORT_SYMBOL(cfpkt_extr_head);
149
150int 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)) {
159		PKT_ERROR(pkt, "linearize failed\n");
160		return -EPROTO;
161	}
162	if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
163		PKT_ERROR(pkt, "read beyond end of packet\n");
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}
171
172int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
173{
174	return cfpkt_add_body(pkt, NULL, len);
175}
176
177int 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)) {
203			PKT_ERROR(pkt, "cow failed\n");
204			return -EPROTO;
205		}
206	}
207
208	/* All set to put the last SKB and optionally write data there. */
209	to = pskb_put(skb, lastskb, len);
210	if (likely(data))
211		memcpy(to, data, len);
212	return 0;
213}
214
215inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
216{
217	return cfpkt_add_body(pkt, &data, 1);
218}
219
220int 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;
226	int ret;
227	if (unlikely(is_erronous(pkt)))
228		return -EPROTO;
229	if (unlikely(skb_headroom(skb) < len)) {
230		PKT_ERROR(pkt, "no headroom\n");
231		return -EPROTO;
232	}
233
234	/* Make sure data is writable */
235	ret = skb_cow_data(skb, 0, &lastskb);
236	if (unlikely(ret < 0)) {
237		PKT_ERROR(pkt, "cow failed\n");
238		return ret;
239	}
240
241	to = skb_push(skb, len);
242	memcpy(to, data, len);
243	return 0;
244}
245EXPORT_SYMBOL(cfpkt_add_head);
246
247inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
248{
249	return cfpkt_add_body(pkt, data, len);
250}
251
252inline u16 cfpkt_getlen(struct cfpkt *pkt)
253{
254	struct sk_buff *skb = pkt_to_skb(pkt);
255	return skb->len;
256}
257
258int cfpkt_iterate(struct cfpkt *pkt,
259		  u16 (*iter_func)(u16, void *, u16),
260		  u16 data)
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)) {
269		PKT_ERROR(pkt, "linearize failed\n");
270		return -EPROTO;
271	}
272	return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
273}
274
275int 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)))
294		PKT_ERROR(pkt, "skb_pad_trail failed\n");
295
296	return cfpkt_getlen(pkt);
297}
298
299struct cfpkt *cfpkt_append(struct cfpkt *dstpkt,
300			   struct cfpkt *addpkt,
301			   u16 expectlen)
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))) {
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 */
320		struct cfpkt *tmppkt;
321		dstlen = skb_headlen(dst);
322		createlen = dstlen + neededtailspace;
323		tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
324		if (tmppkt == NULL)
325			return NULL;
326		tmp = pkt_to_skb(tmppkt);
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}
339
340struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
341{
342	struct sk_buff *skb2;
343	struct sk_buff *skb = pkt_to_skb(pkt);
344	struct cfpkt *tmppkt;
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)) {
352		PKT_ERROR(pkt, "trying to split beyond end of packet\n");
353		return NULL;
354	}
355
356	/* Create a new packet for the second part of the data */
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
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;
374	skb2->priority = skb->priority;
375	return skb_to_pkt(skb2);
376}
377
378bool cfpkt_erroneous(struct cfpkt *pkt)
379{
380	return cfpkt_priv(pkt)->erronous;
381}
382
383struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
384{
385	return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
386}
387EXPORT_SYMBOL(cfpkt_info);
388
389void cfpkt_set_prio(struct cfpkt *pkt, int prio)
390{
391	pkt_to_skb(pkt)->priority = prio;
392}
393EXPORT_SYMBOL(cfpkt_set_prio);
394