aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/kfifo.c
blob: 498cabba225e9c90fa37edc1cda2120dbcd27a1f (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
/*
 * A generic kernel FIFO implementation.
 *
 * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net>
 * Copyright (C) 2004 Stelian Pop <stelian@popies.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/kfifo.h>
#include <linux/log2.h>
#include <linux/uaccess.h>

static void _kfifo_init(struct kfifo *fifo, void *buffer,
		unsigned int size)
{
	fifo->buffer = buffer;
	fifo->size = size;

	kfifo_reset(fifo);
}

/**
 * kfifo_init - initialize a FIFO using a preallocated buffer
 * @fifo: the fifo to assign the buffer
 * @buffer: the preallocated buffer to be used.
 * @size: the size of the internal buffer, this has to be a power of 2.
 *
 */
void kfifo_init(struct kfifo *fifo, void *buffer, unsigned int size)
{
	/* size must be a power of 2 */
	BUG_ON(!is_power_of_2(size));

	_kfifo_init(fifo, buffer, size);
}
EXPORT_SYMBOL(kfifo_init);

/**
 * kfifo_alloc - allocates a new FIFO internal buffer
 * @fifo: the fifo to assign then new buffer
 * @size: the size of the buffer to be allocated, this have to be a power of 2.
 * @gfp_mask: get_free_pages mask, passed to kmalloc()
 *
 * This function dynamically allocates a new fifo internal buffer
 *
 * The size will be rounded-up to a power of 2.
 * The buffer will be release with kfifo_free().
 * Return 0 if no error, otherwise the an error code
 */
int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask)
{
	unsigned char *buffer;

	/*
	 * round up to the next power of 2, since our 'let the indices
	 * wrap' technique works only in this case.
	 */
	if (!is_power_of_2(size)) {
		BUG_ON(size > 0x80000000);
		size = roundup_pow_of_two(size);
	}

	buffer = kmalloc(size, gfp_mask);
	if (!buffer) {
		_kfifo_init(fifo, 0, 0);
		return -ENOMEM;
	}

	_kfifo_init(fifo, buffer, size);

	return 0;
}
EXPORT_SYMBOL(kfifo_alloc);

/**
 * kfifo_free - frees the FIFO internal buffer
 * @fifo: the fifo to be freed.
 */
void kfifo_free(struct kfifo *fifo)
{
	kfree(fifo->buffer);
}
EXPORT_SYMBOL(kfifo_free);

/**
 * kfifo_skip - skip output data
 * @fifo: the fifo to be used.
 * @len: number of bytes to skip
 */
void kfifo_skip(struct kfifo *fifo, unsigned int len)
{
	if (len < kfifo_len(fifo)) {
		__kfifo_add_out(fifo, len);
		return;
	}
	kfifo_reset_out(fifo);
}
EXPORT_SYMBOL(kfifo_skip);

static inline void __kfifo_in_data(struct kfifo *fifo,
		const void *from, unsigned int len, unsigned int off)
{
	unsigned int l;

	/*
	 * Ensure that we sample the fifo->out index -before- we
	 * start putting bytes into the kfifo.
	 */

	smp_mb();

	off = __kfifo_off(fifo, fifo->in + off);

	/* first put the data starting from fifo->in to buffer end */
	l = min(len, fifo->size - off);
	memcpy(fifo->buffer + off, from, l);

	/* then put the rest (if any) at the beginning of the buffer */
	memcpy(fifo->buffer, from + l, len - l);
}

static inline void __kfifo_out_data(struct kfifo *fifo,
		void *to, unsigned int len, unsigned int off)
{
	unsigned int l;

	/*
	 * Ensure that we sample the fifo->in index -before- we
	 * start removing bytes from the kfifo.
	 */

	smp_rmb();

	off = __kfifo_off(fifo, fifo->out + off);

	/* first get the data from fifo->out until the end of the buffer */
	l = min(len, fifo->size - off);
	memcpy(to, fifo->buffer + off, l);

	/* then get the rest (if any) from the beginning of the buffer */
	memcpy(to + l, fifo->buffer, len - l);
}

static inline int __kfifo_from_user_data(struct kfifo *fifo,
	 const void __user *from, unsigned int len, unsigned int off,
	 unsigned *lenout)
{
	unsigned int l;
	int ret;

	/*
	 * Ensure that we sample the fifo->out index -before- we
	 * start putting bytes into the kfifo.
	 */

	smp_mb();

	off = __kfifo_off(fifo, fifo->in + off);

	/* first put the data starting from fifo->in to buffer end */
	l = min(len, fifo->size - off);
	ret = copy_from_user(fifo->buffer + off, from, l);
	if (unlikely(ret)) {
		*lenout = ret;
		return -EFAULT;
	}
	*lenout = l;

	/* then put the rest (if any) at the beginning of the buffer */
	ret = copy_from_user(fifo->buffer, from + l, len - l);
	*lenout += ret ? ret : len - l;
	return ret ? -EFAULT : 0;
}

static inline int __kfifo_to_user_data(struct kfifo *fifo,
		void __user *to, unsigned int len, unsigned int off, unsigned *lenout)
{
	unsigned int l;
	int ret;

	/*
	 * Ensure that we sample the fifo->in index -before- we
	 * start removing bytes from the kfifo.
	 */

	smp_rmb();

	off = __kfifo_off(fifo, fifo->out + off);

	/* first get the data from fifo->out until the end of the buffer */
	l = min(len, fifo->size - off);
	ret = copy_to_user(to, fifo->buffer + off, l);
	*lenout = l;
	if (unlikely(ret)) {
		*lenout -= ret;
		return -EFAULT;
	}

	/* then get the rest (if any) from the beginning of the buffer */
	len -= l;
	ret = copy_to_user(to + l, fifo->buffer, len);
	if (unlikely(ret)) {
		*lenout += len - ret;
		return -EFAULT;
	}
	*lenout += len;
	return 0;
}

unsigned int __kfifo_in_n(struct kfifo *fifo,
	const void *from, unsigned int len, unsigned int recsize)
{
	if (kfifo_avail(fifo) < len + recsize)
		return len + 1;

	__kfifo_in_data(fifo, from, len, recsize);
	return 0;
}
EXPORT_SYMBOL(__kfifo_in_n);

/**
 * kfifo_in - puts some data into the FIFO
 * @fifo: the fifo to be used.
 * @from: the data to be added.
 * @len: the length of the data to be added.
 *
 * This function copies at most @len bytes from the @from buffer into
 * the FIFO depending on the free space, and returns the number of
 * bytes copied.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these functions.
 */
unsigned int kfifo_in(struct kfifo *fifo, const void *from,
				unsigned int len)
{
	len = min(kfifo_avail(fifo), len);

	__kfifo_in_data(fifo, from, len, 0);
	__kfifo_add_in(fifo, len);
	return len;
}
EXPORT_SYMBOL(kfifo_in);

unsigned int __kfifo_in_generic(struct kfifo *fifo,
	const void *from, unsigned int len, unsigned int recsize)
{
	return __kfifo_in_rec(fifo, from, len, recsize);
}
EXPORT_SYMBOL(__kfifo_in_generic);

unsigned int __kfifo_out_n(struct kfifo *fifo,
	void *to, unsigned int len, unsigned int recsize)
{
	if (kfifo_len(fifo) < len + recsize)
		return len;

	__kfifo_out_data(fifo, to, len, recsize);
	__kfifo_add_out(fifo, len + recsize);
	return 0;
}
EXPORT_SYMBOL(__kfifo_out_n);

/**
 * kfifo_out - gets some data from the FIFO
 * @fifo: the fifo to be used.
 * @to: where the data must be copied.
 * @len: the size of the destination buffer.
 *
 * This function copies at most @len bytes from the FIFO into the
 * @to buffer and returns the number of copied bytes.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these functions.
 */
unsigned int kfifo_out(struct kfifo *fifo, void *to, unsigned int len)
{
	len = min(kfifo_len(fifo), len);

	__kfifo_out_data(fifo, to, len, 0);
	__kfifo_add_out(fifo, len);

	return len;
}
EXPORT_SYMBOL(kfifo_out);

/**
 * kfifo_out_peek - copy some data from the FIFO, but do not remove it
 * @fifo: the fifo to be used.
 * @to: where the data must be copied.
 * @len: the size of the destination buffer.
 * @offset: offset into the fifo
 *
 * This function copies at most @len bytes at @offset from the FIFO
 * into the @to buffer and returns the number of copied bytes.
 * The data is not removed from the FIFO.
 */
unsigned int kfifo_out_peek(struct kfifo *fifo, void *to, unsigned int len,
			    unsigned offset)
{
	len = min(kfifo_len(fifo), len + offset);

	__kfifo_out_data(fifo, to, len, offset);
	return len;
}
EXPORT_SYMBOL(kfifo_out_peek);

unsigned int __kfifo_out_generic(struct kfifo *fifo,
	void *to, unsigned int len, unsigned int recsize,
	unsigned int *total)
{
	return __kfifo_out_rec(fifo, to, len, recsize, total);
}
EXPORT_SYMBOL(__kfifo_out_generic);

unsigned int __kfifo_from_user_n(struct kfifo *fifo,
	const void __user *from, unsigned int len, unsigned int recsize)
{
	unsigned total;

	if (kfifo_avail(fifo) < len + recsize)
		return len + 1;

	__kfifo_from_user_data(fifo, from, len, recsize, &total);
	return total;
}
EXPORT_SYMBOL(__kfifo_from_user_n);

/**
 * kfifo_from_user - puts some data from user space into the FIFO
 * @fifo: the fifo to be used.
 * @from: pointer to the data to be added.
 * @len: the length of the data to be added.
 * @total: the actual returned data length.
 *
 * This function copies at most @len bytes from the @from into the
 * FIFO depending and returns -EFAULT/0.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these functions.
 */
int kfifo_from_user(struct kfifo *fifo,
        const void __user *from, unsigned int len, unsigned *total)
{
	int ret;
	len = min(kfifo_avail(fifo), len);
	ret = __kfifo_from_user_data(fifo, from, len, 0, total);
	if (ret)
		return ret;
	__kfifo_add_in(fifo, len);
	return 0;
}
EXPORT_SYMBOL(kfifo_from_user);

unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
	const void __user *from, unsigned int len, unsigned int recsize)
{
	return __kfifo_from_user_rec(fifo, from, len, recsize);
}
EXPORT_SYMBOL(__kfifo_from_user_generic);

unsigned int __kfifo_to_user_n(struct kfifo *fifo,
	void __user *to, unsigned int len, unsigned int reclen,
	unsigned int recsize)
{
	unsigned int ret, total;

	if (kfifo_len(fifo) < reclen + recsize)
		return len;

	ret = __kfifo_to_user_data(fifo, to, reclen, recsize, &total);

	if (likely(ret == 0))
		__kfifo_add_out(fifo, reclen + recsize);

	return total;
}
EXPORT_SYMBOL(__kfifo_to_user_n);

/**
 * kfifo_to_user - gets data from the FIFO and write it to user space
 * @fifo: the fifo to be used.
 * @to: where the data must be copied.
 * @len: the size of the destination buffer.
 * @lenout: pointer to output variable with copied data
 *
 * This function copies at most @len bytes from the FIFO into the
 * @to buffer and 0 or -EFAULT.
 *
 * Note that with only one concurrent reader and one concurrent
 * writer, you don't need extra locking to use these functions.
 */
int kfifo_to_user(struct kfifo *fifo,
	void __user *to, unsigned int len, unsigned *lenout)
{
	int ret;
	len = min(kfifo_len(fifo), len);
	ret = __kfifo_to_user_data(fifo, to, len, 0, lenout);
	__kfifo_add_out(fifo, *lenout);
	return ret;
}
EXPORT_SYMBOL(kfifo_to_user);

unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
	void __user *to, unsigned int len, unsigned int recsize,
	unsigned int *total)
{
	return __kfifo_to_user_rec(fifo, to, len, recsize, total);
}
EXPORT_SYMBOL(__kfifo_to_user_generic);

unsigned int __kfifo_peek_generic(struct kfifo *fifo, unsigned int recsize)
{
	if (recsize == 0)
		return kfifo_avail(fifo);

	return __kfifo_peek_n(fifo, recsize);
}
EXPORT_SYMBOL(__kfifo_peek_generic);

void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize)
{
	__kfifo_skip_rec(fifo, recsize);
}
EXPORT_SYMBOL(__kfifo_skip_generic);