1 /*
2  * A generic kernel FIFO implementation
3  *
4  * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  *
20  */
21 
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/slab.h>
25 #include <linux/err.h>
26 #include <linux/log2.h>
27 #include <linux/uaccess.h>
28 #include <linux/kfifo.h>
29 
30 /*
31  * internal helper to calculate the unused elements in a fifo
32  */
kfifo_unused(struct __kfifo * fifo)33 static inline unsigned int kfifo_unused(struct __kfifo *fifo)
34 {
35 	return (fifo->mask + 1) - (fifo->in - fifo->out);
36 }
37 
__kfifo_alloc(struct __kfifo * fifo,unsigned int size,size_t esize,gfp_t gfp_mask)38 int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
39 		size_t esize, gfp_t gfp_mask)
40 {
41 	/*
42 	 * round down to the next power of 2, since our 'let the indices
43 	 * wrap' technique works only in this case.
44 	 */
45 	if (!is_power_of_2(size))
46 		size = rounddown_pow_of_two(size);
47 
48 	fifo->in = 0;
49 	fifo->out = 0;
50 	fifo->esize = esize;
51 
52 	if (size < 2) {
53 		fifo->data = NULL;
54 		fifo->mask = 0;
55 		return -EINVAL;
56 	}
57 
58 	fifo->data = kmalloc(size * esize, gfp_mask);
59 
60 	if (!fifo->data) {
61 		fifo->mask = 0;
62 		return -ENOMEM;
63 	}
64 	fifo->mask = size - 1;
65 
66 	return 0;
67 }
68 EXPORT_SYMBOL(__kfifo_alloc);
69 
__kfifo_free(struct __kfifo * fifo)70 void __kfifo_free(struct __kfifo *fifo)
71 {
72 	kfree(fifo->data);
73 	fifo->in = 0;
74 	fifo->out = 0;
75 	fifo->esize = 0;
76 	fifo->data = NULL;
77 	fifo->mask = 0;
78 }
79 EXPORT_SYMBOL(__kfifo_free);
80 
__kfifo_init(struct __kfifo * fifo,void * buffer,unsigned int size,size_t esize)81 int __kfifo_init(struct __kfifo *fifo, void *buffer,
82 		unsigned int size, size_t esize)
83 {
84 	size /= esize;
85 
86 	if (!is_power_of_2(size))
87 		size = rounddown_pow_of_two(size);
88 
89 	fifo->in = 0;
90 	fifo->out = 0;
91 	fifo->esize = esize;
92 	fifo->data = buffer;
93 
94 	if (size < 2) {
95 		fifo->mask = 0;
96 		return -EINVAL;
97 	}
98 	fifo->mask = size - 1;
99 
100 	return 0;
101 }
102 EXPORT_SYMBOL(__kfifo_init);
103 
kfifo_copy_in(struct __kfifo * fifo,const void * src,unsigned int len,unsigned int off)104 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
105 		unsigned int len, unsigned int off)
106 {
107 	unsigned int size = fifo->mask + 1;
108 	unsigned int esize = fifo->esize;
109 	unsigned int l;
110 
111 	off &= fifo->mask;
112 	if (esize != 1) {
113 		off *= esize;
114 		size *= esize;
115 		len *= esize;
116 	}
117 	l = min(len, size - off);
118 
119 	memcpy(fifo->data + off, src, l);
120 	memcpy(fifo->data, src + l, len - l);
121 	/*
122 	 * make sure that the data in the fifo is up to date before
123 	 * incrementing the fifo->in index counter
124 	 */
125 	smp_wmb();
126 }
127 
__kfifo_in(struct __kfifo * fifo,const void * buf,unsigned int len)128 unsigned int __kfifo_in(struct __kfifo *fifo,
129 		const void *buf, unsigned int len)
130 {
131 	unsigned int l;
132 
133 	l = kfifo_unused(fifo);
134 	if (len > l)
135 		len = l;
136 
137 	kfifo_copy_in(fifo, buf, len, fifo->in);
138 	fifo->in += len;
139 	return len;
140 }
141 EXPORT_SYMBOL(__kfifo_in);
142 
kfifo_copy_out(struct __kfifo * fifo,void * dst,unsigned int len,unsigned int off)143 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
144 		unsigned int len, unsigned int off)
145 {
146 	unsigned int size = fifo->mask + 1;
147 	unsigned int esize = fifo->esize;
148 	unsigned int l;
149 
150 	off &= fifo->mask;
151 	if (esize != 1) {
152 		off *= esize;
153 		size *= esize;
154 		len *= esize;
155 	}
156 	l = min(len, size - off);
157 
158 	memcpy(dst, fifo->data + off, l);
159 	memcpy(dst + l, fifo->data, len - l);
160 	/*
161 	 * make sure that the data is copied before
162 	 * incrementing the fifo->out index counter
163 	 */
164 	smp_wmb();
165 }
166 
__kfifo_out_peek(struct __kfifo * fifo,void * buf,unsigned int len)167 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
168 		void *buf, unsigned int len)
169 {
170 	unsigned int l;
171 
172 	l = fifo->in - fifo->out;
173 	if (len > l)
174 		len = l;
175 
176 	kfifo_copy_out(fifo, buf, len, fifo->out);
177 	return len;
178 }
179 EXPORT_SYMBOL(__kfifo_out_peek);
180 
__kfifo_out(struct __kfifo * fifo,void * buf,unsigned int len)181 unsigned int __kfifo_out(struct __kfifo *fifo,
182 		void *buf, unsigned int len)
183 {
184 	len = __kfifo_out_peek(fifo, buf, len);
185 	fifo->out += len;
186 	return len;
187 }
188 EXPORT_SYMBOL(__kfifo_out);
189 
kfifo_copy_from_user(struct __kfifo * fifo,const void __user * from,unsigned int len,unsigned int off,unsigned int * copied)190 static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
191 	const void __user *from, unsigned int len, unsigned int off,
192 	unsigned int *copied)
193 {
194 	unsigned int size = fifo->mask + 1;
195 	unsigned int esize = fifo->esize;
196 	unsigned int l;
197 	unsigned long ret;
198 
199 	off &= fifo->mask;
200 	if (esize != 1) {
201 		off *= esize;
202 		size *= esize;
203 		len *= esize;
204 	}
205 	l = min(len, size - off);
206 
207 	ret = copy_from_user(fifo->data + off, from, l);
208 	if (unlikely(ret))
209 		ret = DIV_ROUND_UP(ret + len - l, esize);
210 	else {
211 		ret = copy_from_user(fifo->data, from + l, len - l);
212 		if (unlikely(ret))
213 			ret = DIV_ROUND_UP(ret, esize);
214 	}
215 	/*
216 	 * make sure that the data in the fifo is up to date before
217 	 * incrementing the fifo->in index counter
218 	 */
219 	smp_wmb();
220 	*copied = len - ret;
221 	/* return the number of elements which are not copied */
222 	return ret;
223 }
224 
__kfifo_from_user(struct __kfifo * fifo,const void __user * from,unsigned long len,unsigned int * copied)225 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
226 		unsigned long len, unsigned int *copied)
227 {
228 	unsigned int l;
229 	unsigned long ret;
230 	unsigned int esize = fifo->esize;
231 	int err;
232 
233 	if (esize != 1)
234 		len /= esize;
235 
236 	l = kfifo_unused(fifo);
237 	if (len > l)
238 		len = l;
239 
240 	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
241 	if (unlikely(ret)) {
242 		len -= ret;
243 		err = -EFAULT;
244 	} else
245 		err = 0;
246 	fifo->in += len;
247 	return err;
248 }
249 EXPORT_SYMBOL(__kfifo_from_user);
250 
kfifo_copy_to_user(struct __kfifo * fifo,void __user * to,unsigned int len,unsigned int off,unsigned int * copied)251 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
252 		unsigned int len, unsigned int off, unsigned int *copied)
253 {
254 	unsigned int l;
255 	unsigned long ret;
256 	unsigned int size = fifo->mask + 1;
257 	unsigned int esize = fifo->esize;
258 
259 	off &= fifo->mask;
260 	if (esize != 1) {
261 		off *= esize;
262 		size *= esize;
263 		len *= esize;
264 	}
265 	l = min(len, size - off);
266 
267 	ret = copy_to_user(to, fifo->data + off, l);
268 	if (unlikely(ret))
269 		ret = DIV_ROUND_UP(ret + len - l, esize);
270 	else {
271 		ret = copy_to_user(to + l, fifo->data, len - l);
272 		if (unlikely(ret))
273 			ret = DIV_ROUND_UP(ret, esize);
274 	}
275 	/*
276 	 * make sure that the data is copied before
277 	 * incrementing the fifo->out index counter
278 	 */
279 	smp_wmb();
280 	*copied = len - ret;
281 	/* return the number of elements which are not copied */
282 	return ret;
283 }
284 
__kfifo_to_user(struct __kfifo * fifo,void __user * to,unsigned long len,unsigned int * copied)285 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
286 		unsigned long len, unsigned int *copied)
287 {
288 	unsigned int l;
289 	unsigned long ret;
290 	unsigned int esize = fifo->esize;
291 	int err;
292 
293 	if (esize != 1)
294 		len /= esize;
295 
296 	l = fifo->in - fifo->out;
297 	if (len > l)
298 		len = l;
299 	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
300 	if (unlikely(ret)) {
301 		len -= ret;
302 		err = -EFAULT;
303 	} else
304 		err = 0;
305 	fifo->out += len;
306 	return err;
307 }
308 EXPORT_SYMBOL(__kfifo_to_user);
309 
setup_sgl_buf(struct scatterlist * sgl,void * buf,int nents,unsigned int len)310 static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
311 		int nents, unsigned int len)
312 {
313 	int n;
314 	unsigned int l;
315 	unsigned int off;
316 	struct page *page;
317 
318 	if (!nents)
319 		return 0;
320 
321 	if (!len)
322 		return 0;
323 
324 	n = 0;
325 	page = virt_to_page(buf);
326 	off = offset_in_page(buf);
327 	l = 0;
328 
329 	while (len >= l + PAGE_SIZE - off) {
330 		struct page *npage;
331 
332 		l += PAGE_SIZE;
333 		buf += PAGE_SIZE;
334 		npage = virt_to_page(buf);
335 		if (page_to_phys(page) != page_to_phys(npage) - l) {
336 			sg_set_page(sgl, page, l - off, off);
337 			sgl = sg_next(sgl);
338 			if (++n == nents || sgl == NULL)
339 				return n;
340 			page = npage;
341 			len -= l - off;
342 			l = off = 0;
343 		}
344 	}
345 	sg_set_page(sgl, page, len, off);
346 	return n + 1;
347 }
348 
setup_sgl(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len,unsigned int off)349 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
350 		int nents, unsigned int len, unsigned int off)
351 {
352 	unsigned int size = fifo->mask + 1;
353 	unsigned int esize = fifo->esize;
354 	unsigned int l;
355 	unsigned int n;
356 
357 	off &= fifo->mask;
358 	if (esize != 1) {
359 		off *= esize;
360 		size *= esize;
361 		len *= esize;
362 	}
363 	l = min(len, size - off);
364 
365 	n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
366 	n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
367 
368 	return n;
369 }
370 
__kfifo_dma_in_prepare(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len)371 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
372 		struct scatterlist *sgl, int nents, unsigned int len)
373 {
374 	unsigned int l;
375 
376 	l = kfifo_unused(fifo);
377 	if (len > l)
378 		len = l;
379 
380 	return setup_sgl(fifo, sgl, nents, len, fifo->in);
381 }
382 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
383 
__kfifo_dma_out_prepare(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len)384 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
385 		struct scatterlist *sgl, int nents, unsigned int len)
386 {
387 	unsigned int l;
388 
389 	l = fifo->in - fifo->out;
390 	if (len > l)
391 		len = l;
392 
393 	return setup_sgl(fifo, sgl, nents, len, fifo->out);
394 }
395 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
396 
__kfifo_max_r(unsigned int len,size_t recsize)397 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
398 {
399 	unsigned int max = (1 << (recsize << 3)) - 1;
400 
401 	if (len > max)
402 		return max;
403 	return len;
404 }
405 
406 #define	__KFIFO_PEEK(data, out, mask) \
407 	((data)[(out) & (mask)])
408 /*
409  * __kfifo_peek_n internal helper function for determinate the length of
410  * the next record in the fifo
411  */
__kfifo_peek_n(struct __kfifo * fifo,size_t recsize)412 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
413 {
414 	unsigned int l;
415 	unsigned int mask = fifo->mask;
416 	unsigned char *data = fifo->data;
417 
418 	l = __KFIFO_PEEK(data, fifo->out, mask);
419 
420 	if (--recsize)
421 		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
422 
423 	return l;
424 }
425 
426 #define	__KFIFO_POKE(data, in, mask, val) \
427 	( \
428 	(data)[(in) & (mask)] = (unsigned char)(val) \
429 	)
430 
431 /*
432  * __kfifo_poke_n internal helper function for storeing the length of
433  * the record into the fifo
434  */
__kfifo_poke_n(struct __kfifo * fifo,unsigned int n,size_t recsize)435 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
436 {
437 	unsigned int mask = fifo->mask;
438 	unsigned char *data = fifo->data;
439 
440 	__KFIFO_POKE(data, fifo->in, mask, n);
441 
442 	if (recsize > 1)
443 		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
444 }
445 
__kfifo_len_r(struct __kfifo * fifo,size_t recsize)446 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
447 {
448 	return __kfifo_peek_n(fifo, recsize);
449 }
450 EXPORT_SYMBOL(__kfifo_len_r);
451 
__kfifo_in_r(struct __kfifo * fifo,const void * buf,unsigned int len,size_t recsize)452 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
453 		unsigned int len, size_t recsize)
454 {
455 	if (len + recsize > kfifo_unused(fifo))
456 		return 0;
457 
458 	__kfifo_poke_n(fifo, len, recsize);
459 
460 	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
461 	fifo->in += len + recsize;
462 	return len;
463 }
464 EXPORT_SYMBOL(__kfifo_in_r);
465 
kfifo_out_copy_r(struct __kfifo * fifo,void * buf,unsigned int len,size_t recsize,unsigned int * n)466 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
467 	void *buf, unsigned int len, size_t recsize, unsigned int *n)
468 {
469 	*n = __kfifo_peek_n(fifo, recsize);
470 
471 	if (len > *n)
472 		len = *n;
473 
474 	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
475 	return len;
476 }
477 
__kfifo_out_peek_r(struct __kfifo * fifo,void * buf,unsigned int len,size_t recsize)478 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
479 		unsigned int len, size_t recsize)
480 {
481 	unsigned int n;
482 
483 	if (fifo->in == fifo->out)
484 		return 0;
485 
486 	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
487 }
488 EXPORT_SYMBOL(__kfifo_out_peek_r);
489 
__kfifo_out_r(struct __kfifo * fifo,void * buf,unsigned int len,size_t recsize)490 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
491 		unsigned int len, size_t recsize)
492 {
493 	unsigned int n;
494 
495 	if (fifo->in == fifo->out)
496 		return 0;
497 
498 	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
499 	fifo->out += n + recsize;
500 	return len;
501 }
502 EXPORT_SYMBOL(__kfifo_out_r);
503 
__kfifo_skip_r(struct __kfifo * fifo,size_t recsize)504 void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
505 {
506 	unsigned int n;
507 
508 	n = __kfifo_peek_n(fifo, recsize);
509 	fifo->out += n + recsize;
510 }
511 EXPORT_SYMBOL(__kfifo_skip_r);
512 
__kfifo_from_user_r(struct __kfifo * fifo,const void __user * from,unsigned long len,unsigned int * copied,size_t recsize)513 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
514 	unsigned long len, unsigned int *copied, size_t recsize)
515 {
516 	unsigned long ret;
517 
518 	len = __kfifo_max_r(len, recsize);
519 
520 	if (len + recsize > kfifo_unused(fifo)) {
521 		*copied = 0;
522 		return 0;
523 	}
524 
525 	__kfifo_poke_n(fifo, len, recsize);
526 
527 	ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
528 	if (unlikely(ret)) {
529 		*copied = 0;
530 		return -EFAULT;
531 	}
532 	fifo->in += len + recsize;
533 	return 0;
534 }
535 EXPORT_SYMBOL(__kfifo_from_user_r);
536 
__kfifo_to_user_r(struct __kfifo * fifo,void __user * to,unsigned long len,unsigned int * copied,size_t recsize)537 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
538 	unsigned long len, unsigned int *copied, size_t recsize)
539 {
540 	unsigned long ret;
541 	unsigned int n;
542 
543 	if (fifo->in == fifo->out) {
544 		*copied = 0;
545 		return 0;
546 	}
547 
548 	n = __kfifo_peek_n(fifo, recsize);
549 	if (len > n)
550 		len = n;
551 
552 	ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
553 	if (unlikely(ret)) {
554 		*copied = 0;
555 		return -EFAULT;
556 	}
557 	fifo->out += n + recsize;
558 	return 0;
559 }
560 EXPORT_SYMBOL(__kfifo_to_user_r);
561 
__kfifo_dma_in_prepare_r(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len,size_t recsize)562 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
563 	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
564 {
565 	if (!nents)
566 		BUG();
567 
568 	len = __kfifo_max_r(len, recsize);
569 
570 	if (len + recsize > kfifo_unused(fifo))
571 		return 0;
572 
573 	return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
574 }
575 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
576 
__kfifo_dma_in_finish_r(struct __kfifo * fifo,unsigned int len,size_t recsize)577 void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
578 	unsigned int len, size_t recsize)
579 {
580 	len = __kfifo_max_r(len, recsize);
581 	__kfifo_poke_n(fifo, len, recsize);
582 	fifo->in += len + recsize;
583 }
584 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
585 
__kfifo_dma_out_prepare_r(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len,size_t recsize)586 unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
587 	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
588 {
589 	if (!nents)
590 		BUG();
591 
592 	len = __kfifo_max_r(len, recsize);
593 
594 	if (len + recsize > fifo->in - fifo->out)
595 		return 0;
596 
597 	return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
598 }
599 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
600 
__kfifo_dma_out_finish_r(struct __kfifo * fifo,size_t recsize)601 void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
602 {
603 	unsigned int len;
604 
605 	len = __kfifo_peek_n(fifo, recsize);
606 	fifo->out += len + recsize;
607 }
608 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
609