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Linux/lib/kfifo.c

  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/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>
 29 
 30 /*
 31  * internal helper to calculate the unused elements in a fifo
 32  */
 33 static inline unsigned int kfifo_unused(struct __kfifo *fifo)
 34 {
 35         return (fifo->mask + 1) - (fifo->in - fifo->out);
 36 }
 37 
 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         size = roundup_pow_of_two(size);
 46 
 47         fifo->in = 0;
 48         fifo->out = 0;
 49         fifo->esize = esize;
 50 
 51         if (size < 2) {
 52                 fifo->data = NULL;
 53                 fifo->mask = 0;
 54                 return -EINVAL;
 55         }
 56 
 57         fifo->data = kmalloc(size * esize, gfp_mask);
 58 
 59         if (!fifo->data) {
 60                 fifo->mask = 0;
 61                 return -ENOMEM;
 62         }
 63         fifo->mask = size - 1;
 64 
 65         return 0;
 66 }
 67 EXPORT_SYMBOL(__kfifo_alloc);
 68 
 69 void __kfifo_free(struct __kfifo *fifo)
 70 {
 71         kfree(fifo->data);
 72         fifo->in = 0;
 73         fifo->out = 0;
 74         fifo->esize = 0;
 75         fifo->data = NULL;
 76         fifo->mask = 0;
 77 }
 78 EXPORT_SYMBOL(__kfifo_free);
 79 
 80 int __kfifo_init(struct __kfifo *fifo, void *buffer,
 81                 unsigned int size, size_t esize)
 82 {
 83         size /= esize;
 84 
 85         size = roundup_pow_of_two(size);
 86 
 87         fifo->in = 0;
 88         fifo->out = 0;
 89         fifo->esize = esize;
 90         fifo->data = buffer;
 91 
 92         if (size < 2) {
 93                 fifo->mask = 0;
 94                 return -EINVAL;
 95         }
 96         fifo->mask = size - 1;
 97 
 98         return 0;
 99 }
100 EXPORT_SYMBOL(__kfifo_init);
101 
102 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
103                 unsigned int len, unsigned int off)
104 {
105         unsigned int size = fifo->mask + 1;
106         unsigned int esize = fifo->esize;
107         unsigned int l;
108 
109         off &= fifo->mask;
110         if (esize != 1) {
111                 off *= esize;
112                 size *= esize;
113                 len *= esize;
114         }
115         l = min(len, size - off);
116 
117         memcpy(fifo->data + off, src, l);
118         memcpy(fifo->data, src + l, len - l);
119         /*
120          * make sure that the data in the fifo is up to date before
121          * incrementing the fifo->in index counter
122          */
123         smp_wmb();
124 }
125 
126 unsigned int __kfifo_in(struct __kfifo *fifo,
127                 const void *buf, unsigned int len)
128 {
129         unsigned int l;
130 
131         l = kfifo_unused(fifo);
132         if (len > l)
133                 len = l;
134 
135         kfifo_copy_in(fifo, buf, len, fifo->in);
136         fifo->in += len;
137         return len;
138 }
139 EXPORT_SYMBOL(__kfifo_in);
140 
141 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
142                 unsigned int len, unsigned int off)
143 {
144         unsigned int size = fifo->mask + 1;
145         unsigned int esize = fifo->esize;
146         unsigned int l;
147 
148         off &= fifo->mask;
149         if (esize != 1) {
150                 off *= esize;
151                 size *= esize;
152                 len *= esize;
153         }
154         l = min(len, size - off);
155 
156         memcpy(dst, fifo->data + off, l);
157         memcpy(dst + l, fifo->data, len - l);
158         /*
159          * make sure that the data is copied before
160          * incrementing the fifo->out index counter
161          */
162         smp_wmb();
163 }
164 
165 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
166                 void *buf, unsigned int len)
167 {
168         unsigned int l;
169 
170         l = fifo->in - fifo->out;
171         if (len > l)
172                 len = l;
173 
174         kfifo_copy_out(fifo, buf, len, fifo->out);
175         return len;
176 }
177 EXPORT_SYMBOL(__kfifo_out_peek);
178 
179 unsigned int __kfifo_out(struct __kfifo *fifo,
180                 void *buf, unsigned int len)
181 {
182         len = __kfifo_out_peek(fifo, buf, len);
183         fifo->out += len;
184         return len;
185 }
186 EXPORT_SYMBOL(__kfifo_out);
187 
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)
191 {
192         unsigned int size = fifo->mask + 1;
193         unsigned int esize = fifo->esize;
194         unsigned int l;
195         unsigned long ret;
196 
197         off &= fifo->mask;
198         if (esize != 1) {
199                 off *= esize;
200                 size *= esize;
201                 len *= esize;
202         }
203         l = min(len, size - off);
204 
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);
212         }
213         /*
214          * make sure that the data in the fifo is up to date before
215          * incrementing the fifo->in index counter
216          */
217         smp_wmb();
218         *copied = len - ret * esize;
219         /* return the number of elements which are not copied */
220         return ret;
221 }
222 
223 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
224                 unsigned long len, unsigned int *copied)
225 {
226         unsigned int l;
227         unsigned long ret;
228         unsigned int esize = fifo->esize;
229         int err;
230 
231         if (esize != 1)
232                 len /= esize;
233 
234         l = kfifo_unused(fifo);
235         if (len > l)
236                 len = l;
237 
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;
246 }
247 EXPORT_SYMBOL(__kfifo_from_user);
248 
249 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
250                 unsigned int len, unsigned int off, unsigned int *copied)
251 {
252         unsigned int l;
253         unsigned long ret;
254         unsigned int size = fifo->mask + 1;
255         unsigned int esize = fifo->esize;
256 
257         off &= fifo->mask;
258         if (esize != 1) {
259                 off *= esize;
260                 size *= esize;
261                 len *= esize;
262         }
263         l = min(len, size - off);
264 
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);
272         }
273         /*
274          * make sure that the data is copied before
275          * incrementing the fifo->out index counter
276          */
277         smp_wmb();
278         *copied = len - ret * esize;
279         /* return the number of elements which are not copied */
280         return ret;
281 }
282 
283 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
284                 unsigned long len, unsigned int *copied)
285 {
286         unsigned int l;
287         unsigned long ret;
288         unsigned int esize = fifo->esize;
289         int err;
290 
291         if (esize != 1)
292                 len /= esize;
293 
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;
305 }
306 EXPORT_SYMBOL(__kfifo_to_user);
307 
308 static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
309                 int nents, unsigned int len)
310 {
311         int n;
312         unsigned int l;
313         unsigned int off;
314         struct page *page;
315 
316         if (!nents)
317                 return 0;
318 
319         if (!len)
320                 return 0;
321 
322         n = 0;
323         page = virt_to_page(buf);
324         off = offset_in_page(buf);
325         l = 0;
326 
327         while (len >= l + PAGE_SIZE - off) {
328                 struct page *npage;
329 
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;
341                 }
342         }
343         sg_set_page(sgl, page, len, off);
344         return n + 1;
345 }
346 
347 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
348                 int nents, unsigned int len, unsigned int off)
349 {
350         unsigned int size = fifo->mask + 1;
351         unsigned int esize = fifo->esize;
352         unsigned int l;
353         unsigned int n;
354 
355         off &= fifo->mask;
356         if (esize != 1) {
357                 off *= esize;
358                 size *= esize;
359                 len *= esize;
360         }
361         l = min(len, size - off);
362 
363         n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
364         n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
365 
366         return n;
367 }
368 
369 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
370                 struct scatterlist *sgl, int nents, unsigned int len)
371 {
372         unsigned int l;
373 
374         l = kfifo_unused(fifo);
375         if (len > l)
376                 len = l;
377 
378         return setup_sgl(fifo, sgl, nents, len, fifo->in);
379 }
380 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
381 
382 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
383                 struct scatterlist *sgl, int nents, unsigned int len)
384 {
385         unsigned int l;
386 
387         l = fifo->in - fifo->out;
388         if (len > l)
389                 len = l;
390 
391         return setup_sgl(fifo, sgl, nents, len, fifo->out);
392 }
393 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
394 
395 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
396 {
397         unsigned int max = (1 << (recsize << 3)) - 1;
398 
399         if (len > max)
400                 return max;
401         return len;
402 }
403 EXPORT_SYMBOL(__kfifo_max_r);
404 
405 #define __KFIFO_PEEK(data, out, mask) \
406         ((data)[(out) & (mask)])
407 /*
408  * __kfifo_peek_n internal helper function for determinate the length of
409  * the next record in the fifo
410  */
411 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
412 {
413         unsigned int l;
414         unsigned int mask = fifo->mask;
415         unsigned char *data = fifo->data;
416 
417         l = __KFIFO_PEEK(data, fifo->out, mask);
418 
419         if (--recsize)
420                 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
421 
422         return l;
423 }
424 
425 #define __KFIFO_POKE(data, in, mask, val) \
426         ( \
427         (data)[(in) & (mask)] = (unsigned char)(val) \
428         )
429 
430 /*
431  * __kfifo_poke_n internal helper function for storeing the length of
432  * the record into the fifo
433  */
434 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
435 {
436         unsigned int mask = fifo->mask;
437         unsigned char *data = fifo->data;
438 
439         __KFIFO_POKE(data, fifo->in, mask, n);
440 
441         if (recsize > 1)
442                 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
443 }
444 
445 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
446 {
447         return __kfifo_peek_n(fifo, recsize);
448 }
449 EXPORT_SYMBOL(__kfifo_len_r);
450 
451 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
452                 unsigned int len, size_t recsize)
453 {
454         if (len + recsize > kfifo_unused(fifo))
455                 return 0;
456 
457         __kfifo_poke_n(fifo, len, recsize);
458 
459         kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
460         fifo->in += len + recsize;
461         return len;
462 }
463 EXPORT_SYMBOL(__kfifo_in_r);
464 
465 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
466         void *buf, unsigned int len, size_t recsize, unsigned int *n)
467 {
468         *n = __kfifo_peek_n(fifo, recsize);
469 
470         if (len > *n)
471                 len = *n;
472 
473         kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
474         return len;
475 }
476 
477 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
478                 unsigned int len, size_t recsize)
479 {
480         unsigned int n;
481 
482         if (fifo->in == fifo->out)
483                 return 0;
484 
485         return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
486 }
487 EXPORT_SYMBOL(__kfifo_out_peek_r);
488 
489 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
490                 unsigned int len, size_t recsize)
491 {
492         unsigned int n;
493 
494         if (fifo->in == fifo->out)
495                 return 0;
496 
497         len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
498         fifo->out += n + recsize;
499         return len;
500 }
501 EXPORT_SYMBOL(__kfifo_out_r);
502 
503 void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
504 {
505         unsigned int n;
506 
507         n = __kfifo_peek_n(fifo, recsize);
508         fifo->out += n + recsize;
509 }
510 EXPORT_SYMBOL(__kfifo_skip_r);
511 
512 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
513         unsigned long len, unsigned int *copied, size_t recsize)
514 {
515         unsigned long ret;
516 
517         len = __kfifo_max_r(len, recsize);
518 
519         if (len + recsize > kfifo_unused(fifo)) {
520                 *copied = 0;
521                 return 0;
522         }
523 
524         __kfifo_poke_n(fifo, len, recsize);
525 
526         ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
527         if (unlikely(ret)) {
528                 *copied = 0;
529                 return -EFAULT;
530         }
531         fifo->in += len + recsize;
532         return 0;
533 }
534 EXPORT_SYMBOL(__kfifo_from_user_r);
535 
536 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
537         unsigned long len, unsigned int *copied, size_t recsize)
538 {
539         unsigned long ret;
540         unsigned int n;
541 
542         if (fifo->in == fifo->out) {
543                 *copied = 0;
544                 return 0;
545         }
546 
547         n = __kfifo_peek_n(fifo, recsize);
548         if (len > n)
549                 len = n;
550 
551         ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
552         if (unlikely(ret)) {
553                 *copied = 0;
554                 return -EFAULT;
555         }
556         fifo->out += n + recsize;
557         return 0;
558 }
559 EXPORT_SYMBOL(__kfifo_to_user_r);
560 
561 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
562         struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
563 {
564         BUG_ON(!nents);
565 
566         len = __kfifo_max_r(len, recsize);
567 
568         if (len + recsize > kfifo_unused(fifo))
569                 return 0;
570 
571         return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
572 }
573 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
574 
575 void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
576         unsigned int len, size_t recsize)
577 {
578         len = __kfifo_max_r(len, recsize);
579         __kfifo_poke_n(fifo, len, recsize);
580         fifo->in += len + recsize;
581 }
582 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
583 
584 unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
585         struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
586 {
587         BUG_ON(!nents);
588 
589         len = __kfifo_max_r(len, recsize);
590 
591         if (len + recsize > fifo->in - fifo->out)
592                 return 0;
593 
594         return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
595 }
596 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
597 
598 void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
599 {
600         unsigned int len;
601 
602         len = __kfifo_peek_n(fifo, recsize);
603         fifo->out += len + recsize;
604 }
605 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
606 

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