Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost
[cris-mirror.git] / lib / kfifo.c
blob90ba1eb1df06e5283a2dad9132b53346f5106812
1 /*
2 * A generic kernel FIFO implementation
4 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
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.
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.
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.
22 #include <linux/kernel.h>
23 #include <linux/export.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>
31 * internal helper to calculate the unused elements in a fifo
33 static inline unsigned int kfifo_unused(struct __kfifo *fifo)
35 return (fifo->mask + 1) - (fifo->in - fifo->out);
38 int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
39 size_t esize, gfp_t gfp_mask)
42 * round down to the next power of 2, since our 'let the indices
43 * wrap' technique works only in this case.
45 size = roundup_pow_of_two(size);
47 fifo->in = 0;
48 fifo->out = 0;
49 fifo->esize = esize;
51 if (size < 2) {
52 fifo->data = NULL;
53 fifo->mask = 0;
54 return -EINVAL;
57 fifo->data = kmalloc(size * esize, gfp_mask);
59 if (!fifo->data) {
60 fifo->mask = 0;
61 return -ENOMEM;
63 fifo->mask = size - 1;
65 return 0;
67 EXPORT_SYMBOL(__kfifo_alloc);
69 void __kfifo_free(struct __kfifo *fifo)
71 kfree(fifo->data);
72 fifo->in = 0;
73 fifo->out = 0;
74 fifo->esize = 0;
75 fifo->data = NULL;
76 fifo->mask = 0;
78 EXPORT_SYMBOL(__kfifo_free);
80 int __kfifo_init(struct __kfifo *fifo, void *buffer,
81 unsigned int size, size_t esize)
83 size /= esize;
85 size = roundup_pow_of_two(size);
87 fifo->in = 0;
88 fifo->out = 0;
89 fifo->esize = esize;
90 fifo->data = buffer;
92 if (size < 2) {
93 fifo->mask = 0;
94 return -EINVAL;
96 fifo->mask = size - 1;
98 return 0;
100 EXPORT_SYMBOL(__kfifo_init);
102 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
103 unsigned int len, unsigned int off)
105 unsigned int size = fifo->mask + 1;
106 unsigned int esize = fifo->esize;
107 unsigned int l;
109 off &= fifo->mask;
110 if (esize != 1) {
111 off *= esize;
112 size *= esize;
113 len *= esize;
115 l = min(len, size - off);
117 memcpy(fifo->data + off, src, l);
118 memcpy(fifo->data, src + l, len - l);
120 * make sure that the data in the fifo is up to date before
121 * incrementing the fifo->in index counter
123 smp_wmb();
126 unsigned int __kfifo_in(struct __kfifo *fifo,
127 const void *buf, unsigned int len)
129 unsigned int l;
131 l = kfifo_unused(fifo);
132 if (len > l)
133 len = l;
135 kfifo_copy_in(fifo, buf, len, fifo->in);
136 fifo->in += len;
137 return len;
139 EXPORT_SYMBOL(__kfifo_in);
141 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
142 unsigned int len, unsigned int off)
144 unsigned int size = fifo->mask + 1;
145 unsigned int esize = fifo->esize;
146 unsigned int l;
148 off &= fifo->mask;
149 if (esize != 1) {
150 off *= esize;
151 size *= esize;
152 len *= esize;
154 l = min(len, size - off);
156 memcpy(dst, fifo->data + off, l);
157 memcpy(dst + l, fifo->data, len - l);
159 * make sure that the data is copied before
160 * incrementing the fifo->out index counter
162 smp_wmb();
165 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
166 void *buf, unsigned int len)
168 unsigned int l;
170 l = fifo->in - fifo->out;
171 if (len > l)
172 len = l;
174 kfifo_copy_out(fifo, buf, len, fifo->out);
175 return len;
177 EXPORT_SYMBOL(__kfifo_out_peek);
179 unsigned int __kfifo_out(struct __kfifo *fifo,
180 void *buf, unsigned int len)
182 len = __kfifo_out_peek(fifo, buf, len);
183 fifo->out += len;
184 return len;
186 EXPORT_SYMBOL(__kfifo_out);
188 static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
189 const void __user *from, unsigned int len, unsigned int off,
190 unsigned int *copied)
192 unsigned int size = fifo->mask + 1;
193 unsigned int esize = fifo->esize;
194 unsigned int l;
195 unsigned long ret;
197 off &= fifo->mask;
198 if (esize != 1) {
199 off *= esize;
200 size *= esize;
201 len *= esize;
203 l = min(len, size - off);
205 ret = copy_from_user(fifo->data + off, from, l);
206 if (unlikely(ret))
207 ret = DIV_ROUND_UP(ret + len - l, esize);
208 else {
209 ret = copy_from_user(fifo->data, from + l, len - l);
210 if (unlikely(ret))
211 ret = DIV_ROUND_UP(ret, esize);
214 * make sure that the data in the fifo is up to date before
215 * incrementing the fifo->in index counter
217 smp_wmb();
218 *copied = len - ret * esize;
219 /* return the number of elements which are not copied */
220 return ret;
223 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
224 unsigned long len, unsigned int *copied)
226 unsigned int l;
227 unsigned long ret;
228 unsigned int esize = fifo->esize;
229 int err;
231 if (esize != 1)
232 len /= esize;
234 l = kfifo_unused(fifo);
235 if (len > l)
236 len = l;
238 ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
239 if (unlikely(ret)) {
240 len -= ret;
241 err = -EFAULT;
242 } else
243 err = 0;
244 fifo->in += len;
245 return err;
247 EXPORT_SYMBOL(__kfifo_from_user);
249 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
250 unsigned int len, unsigned int off, unsigned int *copied)
252 unsigned int l;
253 unsigned long ret;
254 unsigned int size = fifo->mask + 1;
255 unsigned int esize = fifo->esize;
257 off &= fifo->mask;
258 if (esize != 1) {
259 off *= esize;
260 size *= esize;
261 len *= esize;
263 l = min(len, size - off);
265 ret = copy_to_user(to, fifo->data + off, l);
266 if (unlikely(ret))
267 ret = DIV_ROUND_UP(ret + len - l, esize);
268 else {
269 ret = copy_to_user(to + l, fifo->data, len - l);
270 if (unlikely(ret))
271 ret = DIV_ROUND_UP(ret, esize);
274 * make sure that the data is copied before
275 * incrementing the fifo->out index counter
277 smp_wmb();
278 *copied = len - ret * esize;
279 /* return the number of elements which are not copied */
280 return ret;
283 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
284 unsigned long len, unsigned int *copied)
286 unsigned int l;
287 unsigned long ret;
288 unsigned int esize = fifo->esize;
289 int err;
291 if (esize != 1)
292 len /= esize;
294 l = fifo->in - fifo->out;
295 if (len > l)
296 len = l;
297 ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
298 if (unlikely(ret)) {
299 len -= ret;
300 err = -EFAULT;
301 } else
302 err = 0;
303 fifo->out += len;
304 return err;
306 EXPORT_SYMBOL(__kfifo_to_user);
308 static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
309 int nents, unsigned int len)
311 int n;
312 unsigned int l;
313 unsigned int off;
314 struct page *page;
316 if (!nents)
317 return 0;
319 if (!len)
320 return 0;
322 n = 0;
323 page = virt_to_page(buf);
324 off = offset_in_page(buf);
325 l = 0;
327 while (len >= l + PAGE_SIZE - off) {
328 struct page *npage;
330 l += PAGE_SIZE;
331 buf += PAGE_SIZE;
332 npage = virt_to_page(buf);
333 if (page_to_phys(page) != page_to_phys(npage) - l) {
334 sg_set_page(sgl, page, l - off, off);
335 sgl = sg_next(sgl);
336 if (++n == nents || sgl == NULL)
337 return n;
338 page = npage;
339 len -= l - off;
340 l = off = 0;
343 sg_set_page(sgl, page, len, off);
344 return n + 1;
347 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
348 int nents, unsigned int len, unsigned int off)
350 unsigned int size = fifo->mask + 1;
351 unsigned int esize = fifo->esize;
352 unsigned int l;
353 unsigned int n;
355 off &= fifo->mask;
356 if (esize != 1) {
357 off *= esize;
358 size *= esize;
359 len *= esize;
361 l = min(len, size - off);
363 n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
364 n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
366 return n;
369 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
370 struct scatterlist *sgl, int nents, unsigned int len)
372 unsigned int l;
374 l = kfifo_unused(fifo);
375 if (len > l)
376 len = l;
378 return setup_sgl(fifo, sgl, nents, len, fifo->in);
380 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
382 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
383 struct scatterlist *sgl, int nents, unsigned int len)
385 unsigned int l;
387 l = fifo->in - fifo->out;
388 if (len > l)
389 len = l;
391 return setup_sgl(fifo, sgl, nents, len, fifo->out);
393 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
395 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
397 unsigned int max = (1 << (recsize << 3)) - 1;
399 if (len > max)
400 return max;
401 return len;
403 EXPORT_SYMBOL(__kfifo_max_r);
405 #define __KFIFO_PEEK(data, out, mask) \
406 ((data)[(out) & (mask)])
408 * __kfifo_peek_n internal helper function for determinate the length of
409 * the next record in the fifo
411 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
413 unsigned int l;
414 unsigned int mask = fifo->mask;
415 unsigned char *data = fifo->data;
417 l = __KFIFO_PEEK(data, fifo->out, mask);
419 if (--recsize)
420 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
422 return l;
425 #define __KFIFO_POKE(data, in, mask, val) \
427 (data)[(in) & (mask)] = (unsigned char)(val) \
431 * __kfifo_poke_n internal helper function for storeing the length of
432 * the record into the fifo
434 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
436 unsigned int mask = fifo->mask;
437 unsigned char *data = fifo->data;
439 __KFIFO_POKE(data, fifo->in, mask, n);
441 if (recsize > 1)
442 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
445 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
447 return __kfifo_peek_n(fifo, recsize);
449 EXPORT_SYMBOL(__kfifo_len_r);
451 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
452 unsigned int len, size_t recsize)
454 if (len + recsize > kfifo_unused(fifo))
455 return 0;
457 __kfifo_poke_n(fifo, len, recsize);
459 kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
460 fifo->in += len + recsize;
461 return len;
463 EXPORT_SYMBOL(__kfifo_in_r);
465 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
466 void *buf, unsigned int len, size_t recsize, unsigned int *n)
468 *n = __kfifo_peek_n(fifo, recsize);
470 if (len > *n)
471 len = *n;
473 kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
474 return len;
477 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
478 unsigned int len, size_t recsize)
480 unsigned int n;
482 if (fifo->in == fifo->out)
483 return 0;
485 return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
487 EXPORT_SYMBOL(__kfifo_out_peek_r);
489 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
490 unsigned int len, size_t recsize)
492 unsigned int n;
494 if (fifo->in == fifo->out)
495 return 0;
497 len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
498 fifo->out += n + recsize;
499 return len;
501 EXPORT_SYMBOL(__kfifo_out_r);
503 void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
505 unsigned int n;
507 n = __kfifo_peek_n(fifo, recsize);
508 fifo->out += n + recsize;
510 EXPORT_SYMBOL(__kfifo_skip_r);
512 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
513 unsigned long len, unsigned int *copied, size_t recsize)
515 unsigned long ret;
517 len = __kfifo_max_r(len, recsize);
519 if (len + recsize > kfifo_unused(fifo)) {
520 *copied = 0;
521 return 0;
524 __kfifo_poke_n(fifo, len, recsize);
526 ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
527 if (unlikely(ret)) {
528 *copied = 0;
529 return -EFAULT;
531 fifo->in += len + recsize;
532 return 0;
534 EXPORT_SYMBOL(__kfifo_from_user_r);
536 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
537 unsigned long len, unsigned int *copied, size_t recsize)
539 unsigned long ret;
540 unsigned int n;
542 if (fifo->in == fifo->out) {
543 *copied = 0;
544 return 0;
547 n = __kfifo_peek_n(fifo, recsize);
548 if (len > n)
549 len = n;
551 ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
552 if (unlikely(ret)) {
553 *copied = 0;
554 return -EFAULT;
556 fifo->out += n + recsize;
557 return 0;
559 EXPORT_SYMBOL(__kfifo_to_user_r);
561 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
562 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
564 BUG_ON(!nents);
566 len = __kfifo_max_r(len, recsize);
568 if (len + recsize > kfifo_unused(fifo))
569 return 0;
571 return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
573 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
575 void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
576 unsigned int len, size_t recsize)
578 len = __kfifo_max_r(len, recsize);
579 __kfifo_poke_n(fifo, len, recsize);
580 fifo->in += len + recsize;
582 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
584 unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
585 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
587 BUG_ON(!nents);
589 len = __kfifo_max_r(len, recsize);
591 if (len + recsize > fifo->in - fifo->out)
592 return 0;
594 return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
596 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
598 void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
600 unsigned int len;
602 len = __kfifo_peek_n(fifo, recsize);
603 fifo->out += len + recsize;
605 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);