aboutsummaryrefslogtreecommitdiff
path: root/kernel/kfifo.c
blob: 4502604ecadf0bc9e1d0d132bc17fc6f3a0ab9d9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
/*
 * A generic kernel FIFO implementation
 *
 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/log2.h>
#include <linux/uaccess.h>
#include <linux/kfifo.h>

/*
 * internal helper to calculate the unused elements in a fifo
 */
static inline unsigned int kfifo_unused(struct __kfifo *fifo)
{
	return (fifo->mask + 1) - (fifo->in - fifo->out);
}

int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
		size_t esize, gfp_t gfp_mask)
{
	/*
	 * round down to the next power of 2, since our 'let the indices
	 * wrap' technique works only in this case.
	 */
	if (!is_power_of_2(size))
		size = rounddown_pow_of_two(size);

	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = esize;

	if (size < 2) {
		fifo->data = NULL;
		fifo->mask = 0;
		return -EINVAL;
	}

	fifo->data = kmalloc(size * esize, gfp_mask);

	if (!fifo->data) {
		fifo->mask = 0;
		return -ENOMEM;
	}
	fifo->mask = size - 1;

	return 0;
}
EXPORT_SYMBOL(__kfifo_alloc);

void __kfifo_free(struct __kfifo *fifo)
{
	kfree(fifo->data);
	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = 0;
	fifo->data = NULL;
	fifo->mask = 0;
}
EXPORT_SYMBOL(__kfifo_free);

int __kfifo_init(struct __kfifo *fifo, void *buffer,
		unsigned int size, size_t esize)
{
	size /= esize;

	if (!is_power_of_2(size))
		size = rounddown_pow_of_two(size);

	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = esize;
	fifo->data = buffer;

	if (size < 2) {
		fifo->mask = 0;
		return -EINVAL;
	}
	fifo->mask = size - 1;

	return 0;
}
EXPORT_SYMBOL(__kfifo_init);

static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
		unsigned int len, unsigned int off)
{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	memcpy(fifo->data + off, src, l);
	memcpy(fifo->data, src + l, len - l);
	/*
	 * make sure that the data in the fifo is up to date before
	 * incrementing the fifo->in index counter
	 */
	smp_wmb();
}

unsigned int __kfifo_in(struct __kfifo *fifo,
		const void *buf, unsigned int len)
{
	unsigned int l;

	l = kfifo_unused(fifo);
	if (len > l)
		len = l;

	kfifo_copy_in(fifo, buf, len, fifo->in);
	fifo->in += len;
	return len;
}
EXPORT_SYMBOL(__kfifo_in);

static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
		unsigned int len, unsigned int off)
{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	memcpy(dst, fifo->data + off, l);
	memcpy(dst + l, fifo->data, len - l);
	/*
	 * make sure that the data is copied before
	 * incrementing the fifo->out index counter
	 */
	smp_wmb();
}

unsigned int __kfifo_out_peek(struct __kfifo *fifo,
		void *buf, unsigned int len)
{
	unsigned int l;

	l = fifo->in - fifo->out;
	if (len > l)
		len = l;

	kfifo_copy_out(fifo, buf, len, fifo->out);
	return len;
}
EXPORT_SYMBOL(__kfifo_out_peek);

unsigned int __kfifo_out(struct __kfifo *fifo,
		void *buf, unsigned int len)
{
	len = __kfifo_out_peek(fifo, buf, len);
	fifo->out += len;
	return len;
}
EXPORT_SYMBOL(__kfifo_out);

static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
	const void __user *from, unsigned int len, unsigned int off,
	unsigned int *copied)
{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;
	unsigned long ret;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	ret = copy_from_user(fifo->data + off, from, l);
	if (unlikely(ret))
		ret = DIV_ROUND_UP(ret + len - l, esize);
	else {
		ret = copy_from_user(fifo->data, from + l, len - l);
		if (unlikely(ret))
			ret = DIV_ROUND_UP(ret, esize);
	}
	/*
	 * make sure that the data in the fifo is up to date before
	 * incrementing the fifo->in index counter
	 */
	smp_wmb();
	*copied = len - ret;
	/* return the number of elements which are not copied */
	return ret;
}

int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
		unsigned long len, unsigned int *copied)
{
	unsigned int l;
	unsigned long ret;
	unsigned int esize = fifo->esize;
	int err;

	if (esize != 1)
		len /= esize;

	l = kfifo_unused(fifo);
	if (len > l)
		len = l;

	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
	if (unlikely(ret)) {
		len -= ret;
		err = -EFAULT;
	} else
		err = 0;
	fifo->in += len;
	return err;
}
EXPORT_SYMBOL(__kfifo_from_user);

static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
		unsigned int len, unsigned int off, unsigned int *copied)
{
	unsigned int l;
	unsigned long ret;
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	ret = copy_to_user(to, fifo->data + off, l);
	if (unlikely(ret))
		ret = DIV_ROUND_UP(ret + len - l, esize);
	else {
		ret = copy_to_user(to + l, fifo->data, len - l);
		if (unlikely(ret))
			ret = DIV_ROUND_UP(ret, esize);
	}
	/*
	 * make sure that the data is copied before
	 * incrementing the fifo->out index counter
	 */
	smp_wmb();
	*copied = len - ret;
	/* return the number of elements which are not copied */
	return ret;
}

int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
		unsigned long len, unsigned int *copied)
{
	unsigned int l;
	unsigned long ret;
	unsigned int esize = fifo->esize;
	int err;

	if (esize != 1)
		len /= esize;

	l = fifo->in - fifo->out;
	if (len > l)
		len = l;
	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
	if (unlikely(ret)) {
		len -= ret;
		err = -EFAULT;
	} else
		err = 0;
	fifo->out += len;
	return err;
}
EXPORT_SYMBOL(__kfifo_to_user);

static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
		int nents, unsigned int len)
{
	int n;
	unsigned int l;
	unsigned int off;
	struct page *page;

	if (!nents)
		return 0;

	if (!len)
		return 0;

	n = 0;
	page = virt_to_page(buf);
	off = offset_in_page(buf);
	l = 0;

	while (len >= l + PAGE_SIZE - off) {
		struct page *npage;

		l += PAGE_SIZE;
		buf += PAGE_SIZE;
		npage = virt_to_page(buf);
		if (page_to_phys(page) != page_to_phys(npage) - l) {
			sg_set_page(sgl, page, l - off, off);
			sgl = sg_next(sgl);
			if (++n == nents || sgl == NULL)
				return n;
			page = npage;
			len -= l - off;
			l = off = 0;
		}
	}
	sg_set_page(sgl, page, len, off);
	return n + 1;
}

static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
		int nents, unsigned int len, unsigned int off)
{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;
	unsigned int n;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
	n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);

	if (n)
		sg_mark_end(sgl + n - 1);
	return n;
}

unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
		struct scatterlist *sgl, int nents, unsigned int len)
{
	unsigned int l;

	l = kfifo_unused(fifo);
	if (len > l)
		len = l;

	return setup_sgl(fifo, sgl, nents, len, fifo->in);
}
EXPORT_SYMBOL(__kfifo_dma_in_prepare);

unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
		struct scatterlist *sgl, int nents, unsigned int len)
{
	unsigned int l;

	l = fifo->in - fifo->out;
	if (len > l)
		len = l;

	return setup_sgl(fifo, sgl, nents, len, fifo->out);
}
EXPORT_SYMBOL(__kfifo_dma_out_prepare);

unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
{
	unsigned int max = (1 << (recsize << 3)) - 1;

	if (len > max)
		return max;
	return len;
}

#define	__KFIFO_PEEK(data, out, mask) \
	((data)[(out) & (mask)])
/*
 * __kfifo_peek_n internal helper function for determinate the length of
 * the next record in the fifo
 */
static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
{
	unsigned int l;
	unsigned int mask = fifo->mask;
	unsigned char *data = fifo->data;

	l = __KFIFO_PEEK(data, fifo->out, mask);

	if (--recsize)
		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;

	return l;
}

#define	__KFIFO_POKE(data, in, mask, val) \
	( \
	(data)[(in) & (mask)] = (unsigned char)(val) \
	)

/*
 * __kfifo_poke_n internal helper function for storeing the length of
 * the record into the fifo
 */
static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
{
	unsigned int mask = fifo->mask;
	unsigned char *data = fifo->data;

	__KFIFO_POKE(data, fifo->in, mask, n);

	if (recsize > 1)
		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
}

unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
{
	return __kfifo_peek_n(fifo, recsize);
}
EXPORT_SYMBOL(__kfifo_len_r);

unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
		unsigned int len, size_t recsize)
{
	if (len + recsize > kfifo_unused(fifo))
		return 0;

	__kfifo_poke_n(fifo, len, recsize);

	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
	fifo->in += len + recsize;
	return len;
}
EXPORT_SYMBOL(__kfifo_in_r);

static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
	void *buf, unsigned int len, size_t recsize, unsigned int *n)
{
	*n = __kfifo_peek_n(fifo, recsize);

	if (len > *n)
		len = *n;

	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
	return len;
}

unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
		unsigned int len, size_t recsize)
{
	unsigned int n;

	if (fifo->in == fifo->out)
		return 0;

	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
}
EXPORT_SYMBOL(__kfifo_out_peek_r);

unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
		unsigned int len, size_t recsize)
{
	unsigned int n;

	if (fifo->in == fifo->out)
		return 0;

	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
	fifo->out += n + recsize;
	return len;
}
EXPORT_SYMBOL(__kfifo_out_r);

int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
	unsigned long len, unsigned int *copied, size_t recsize)
{
	unsigned long ret;

	len = __kfifo_max_r(len, recsize);

	if (len + recsize > kfifo_unused(fifo)) {
		*copied = 0;
		return 0;
	}

	__kfifo_poke_n(fifo, len, recsize);

	ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
	if (unlikely(ret)) {
		*copied = 0;
		return -EFAULT;
	}
	fifo->in += len + recsize;
	return 0;
}
EXPORT_SYMBOL(__kfifo_from_user_r);

int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
	unsigned long len, unsigned int *copied, size_t recsize)
{
	unsigned long ret;
	unsigned int n;

	if (fifo->in == fifo->out) {
		*copied = 0;
		return 0;
	}

	n = __kfifo_peek_n(fifo, recsize);
	if (len > n)
		len = n;

	ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
	if (unlikely(ret)) {
		*copied = 0;
		return -EFAULT;
	}
	fifo->out += n + recsize;
	return 0;
}
EXPORT_SYMBOL(__kfifo_to_user_r);

unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
{
	if (!nents)
		BUG();

	len = __kfifo_max_r(len, recsize);

	if (len + recsize > kfifo_unused(fifo))
		return 0;

	return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
}
EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);

void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
	unsigned int len, size_t recsize)
{
	len = __kfifo_max_r(len, recsize);
	__kfifo_poke_n(fifo, len, recsize);
	fifo->in += len + recsize;
}
EXPORT_SYMBOL(__kfifo_dma_in_finish_r);

unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
{
	if (!nents)
		BUG();

	len = __kfifo_max_r(len, recsize);

	if (len + recsize > fifo->in - fifo->out)
		return 0;

	return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
}
EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);

void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
{
	unsigned int len;

	len = __kfifo_peek_n(fifo, recsize);
	fifo->out += len + recsize;
}
EXPORT_SYMBOL(__kfifo_dma_out_finish_r);