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Linux/lib/kfifo.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * A generic kernel FIFO implementation
  4  *
  5  * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
  6  */
  7 
  8 #include <linux/kernel.h>
  9 #include <linux/export.h>
 10 #include <linux/slab.h>
 11 #include <linux/err.h>
 12 #include <linux/log2.h>
 13 #include <linux/uaccess.h>
 14 #include <linux/kfifo.h>
 15 
 16 /*
 17  * internal helper to calculate the unused elements in a fifo
 18  */
 19 static inline unsigned int kfifo_unused(struct __kfifo *fifo)
 20 {
 21         return (fifo->mask + 1) - (fifo->in - fifo->out);
 22 }
 23 
 24 int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
 25                 size_t esize, gfp_t gfp_mask)
 26 {
 27         /*
 28          * round up to the next power of 2, since our 'let the indices
 29          * wrap' technique works only in this case.
 30          */
 31         size = roundup_pow_of_two(size);
 32 
 33         fifo->in = 0;
 34         fifo->out = 0;
 35         fifo->esize = esize;
 36 
 37         if (size < 2) {
 38                 fifo->data = NULL;
 39                 fifo->mask = 0;
 40                 return -EINVAL;
 41         }
 42 
 43         fifo->data = kmalloc_array(esize, size, gfp_mask);
 44 
 45         if (!fifo->data) {
 46                 fifo->mask = 0;
 47                 return -ENOMEM;
 48         }
 49         fifo->mask = size - 1;
 50 
 51         return 0;
 52 }
 53 EXPORT_SYMBOL(__kfifo_alloc);
 54 
 55 void __kfifo_free(struct __kfifo *fifo)
 56 {
 57         kfree(fifo->data);
 58         fifo->in = 0;
 59         fifo->out = 0;
 60         fifo->esize = 0;
 61         fifo->data = NULL;
 62         fifo->mask = 0;
 63 }
 64 EXPORT_SYMBOL(__kfifo_free);
 65 
 66 int __kfifo_init(struct __kfifo *fifo, void *buffer,
 67                 unsigned int size, size_t esize)
 68 {
 69         size /= esize;
 70 
 71         if (!is_power_of_2(size))
 72                 size = rounddown_pow_of_two(size);
 73 
 74         fifo->in = 0;
 75         fifo->out = 0;
 76         fifo->esize = esize;
 77         fifo->data = buffer;
 78 
 79         if (size < 2) {
 80                 fifo->mask = 0;
 81                 return -EINVAL;
 82         }
 83         fifo->mask = size - 1;
 84 
 85         return 0;
 86 }
 87 EXPORT_SYMBOL(__kfifo_init);
 88 
 89 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
 90                 unsigned int len, unsigned int off)
 91 {
 92         unsigned int size = fifo->mask + 1;
 93         unsigned int esize = fifo->esize;
 94         unsigned int l;
 95 
 96         off &= fifo->mask;
 97         if (esize != 1) {
 98                 off *= esize;
 99                 size *= esize;
100                 len *= esize;
101         }
102         l = min(len, size - off);
103 
104         memcpy(fifo->data + off, src, l);
105         memcpy(fifo->data, src + l, len - l);
106         /*
107          * make sure that the data in the fifo is up to date before
108          * incrementing the fifo->in index counter
109          */
110         smp_wmb();
111 }
112 
113 unsigned int __kfifo_in(struct __kfifo *fifo,
114                 const void *buf, unsigned int len)
115 {
116         unsigned int l;
117 
118         l = kfifo_unused(fifo);
119         if (len > l)
120                 len = l;
121 
122         kfifo_copy_in(fifo, buf, len, fifo->in);
123         fifo->in += len;
124         return len;
125 }
126 EXPORT_SYMBOL(__kfifo_in);
127 
128 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
129                 unsigned int len, unsigned int off)
130 {
131         unsigned int size = fifo->mask + 1;
132         unsigned int esize = fifo->esize;
133         unsigned int l;
134 
135         off &= fifo->mask;
136         if (esize != 1) {
137                 off *= esize;
138                 size *= esize;
139                 len *= esize;
140         }
141         l = min(len, size - off);
142 
143         memcpy(dst, fifo->data + off, l);
144         memcpy(dst + l, fifo->data, len - l);
145         /*
146          * make sure that the data is copied before
147          * incrementing the fifo->out index counter
148          */
149         smp_wmb();
150 }
151 
152 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
153                 void *buf, unsigned int len)
154 {
155         unsigned int l;
156 
157         l = fifo->in - fifo->out;
158         if (len > l)
159                 len = l;
160 
161         kfifo_copy_out(fifo, buf, len, fifo->out);
162         return len;
163 }
164 EXPORT_SYMBOL(__kfifo_out_peek);
165 
166 unsigned int __kfifo_out(struct __kfifo *fifo,
167                 void *buf, unsigned int len)
168 {
169         len = __kfifo_out_peek(fifo, buf, len);
170         fifo->out += len;
171         return len;
172 }
173 EXPORT_SYMBOL(__kfifo_out);
174 
175 static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
176         const void __user *from, unsigned int len, unsigned int off,
177         unsigned int *copied)
178 {
179         unsigned int size = fifo->mask + 1;
180         unsigned int esize = fifo->esize;
181         unsigned int l;
182         unsigned long ret;
183 
184         off &= fifo->mask;
185         if (esize != 1) {
186                 off *= esize;
187                 size *= esize;
188                 len *= esize;
189         }
190         l = min(len, size - off);
191 
192         ret = copy_from_user(fifo->data + off, from, l);
193         if (unlikely(ret))
194                 ret = DIV_ROUND_UP(ret + len - l, esize);
195         else {
196                 ret = copy_from_user(fifo->data, from + l, len - l);
197                 if (unlikely(ret))
198                         ret = DIV_ROUND_UP(ret, esize);
199         }
200         /*
201          * make sure that the data in the fifo is up to date before
202          * incrementing the fifo->in index counter
203          */
204         smp_wmb();
205         *copied = len - ret * esize;
206         /* return the number of elements which are not copied */
207         return ret;
208 }
209 
210 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
211                 unsigned long len, unsigned int *copied)
212 {
213         unsigned int l;
214         unsigned long ret;
215         unsigned int esize = fifo->esize;
216         int err;
217 
218         if (esize != 1)
219                 len /= esize;
220 
221         l = kfifo_unused(fifo);
222         if (len > l)
223                 len = l;
224 
225         ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
226         if (unlikely(ret)) {
227                 len -= ret;
228                 err = -EFAULT;
229         } else
230                 err = 0;
231         fifo->in += len;
232         return err;
233 }
234 EXPORT_SYMBOL(__kfifo_from_user);
235 
236 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
237                 unsigned int len, unsigned int off, unsigned int *copied)
238 {
239         unsigned int l;
240         unsigned long ret;
241         unsigned int size = fifo->mask + 1;
242         unsigned int esize = fifo->esize;
243 
244         off &= fifo->mask;
245         if (esize != 1) {
246                 off *= esize;
247                 size *= esize;
248                 len *= esize;
249         }
250         l = min(len, size - off);
251 
252         ret = copy_to_user(to, fifo->data + off, l);
253         if (unlikely(ret))
254                 ret = DIV_ROUND_UP(ret + len - l, esize);
255         else {
256                 ret = copy_to_user(to + l, fifo->data, len - l);
257                 if (unlikely(ret))
258                         ret = DIV_ROUND_UP(ret, esize);
259         }
260         /*
261          * make sure that the data is copied before
262          * incrementing the fifo->out index counter
263          */
264         smp_wmb();
265         *copied = len - ret * esize;
266         /* return the number of elements which are not copied */
267         return ret;
268 }
269 
270 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
271                 unsigned long len, unsigned int *copied)
272 {
273         unsigned int l;
274         unsigned long ret;
275         unsigned int esize = fifo->esize;
276         int err;
277 
278         if (esize != 1)
279                 len /= esize;
280 
281         l = fifo->in - fifo->out;
282         if (len > l)
283                 len = l;
284         ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
285         if (unlikely(ret)) {
286                 len -= ret;
287                 err = -EFAULT;
288         } else
289                 err = 0;
290         fifo->out += len;
291         return err;
292 }
293 EXPORT_SYMBOL(__kfifo_to_user);
294 
295 static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
296                 int nents, unsigned int len)
297 {
298         int n;
299         unsigned int l;
300         unsigned int off;
301         struct page *page;
302 
303         if (!nents)
304                 return 0;
305 
306         if (!len)
307                 return 0;
308 
309         n = 0;
310         page = virt_to_page(buf);
311         off = offset_in_page(buf);
312         l = 0;
313 
314         while (len >= l + PAGE_SIZE - off) {
315                 struct page *npage;
316 
317                 l += PAGE_SIZE;
318                 buf += PAGE_SIZE;
319                 npage = virt_to_page(buf);
320                 if (page_to_phys(page) != page_to_phys(npage) - l) {
321                         sg_set_page(sgl, page, l - off, off);
322                         sgl = sg_next(sgl);
323                         if (++n == nents || sgl == NULL)
324                                 return n;
325                         page = npage;
326                         len -= l - off;
327                         l = off = 0;
328                 }
329         }
330         sg_set_page(sgl, page, len, off);
331         return n + 1;
332 }
333 
334 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
335                 int nents, unsigned int len, unsigned int off)
336 {
337         unsigned int size = fifo->mask + 1;
338         unsigned int esize = fifo->esize;
339         unsigned int l;
340         unsigned int n;
341 
342         off &= fifo->mask;
343         if (esize != 1) {
344                 off *= esize;
345                 size *= esize;
346                 len *= esize;
347         }
348         l = min(len, size - off);
349 
350         n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
351         n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
352 
353         return n;
354 }
355 
356 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
357                 struct scatterlist *sgl, int nents, unsigned int len)
358 {
359         unsigned int l;
360 
361         l = kfifo_unused(fifo);
362         if (len > l)
363                 len = l;
364 
365         return setup_sgl(fifo, sgl, nents, len, fifo->in);
366 }
367 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
368 
369 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
370                 struct scatterlist *sgl, int nents, unsigned int len)
371 {
372         unsigned int l;
373 
374         l = fifo->in - fifo->out;
375         if (len > l)
376                 len = l;
377 
378         return setup_sgl(fifo, sgl, nents, len, fifo->out);
379 }
380 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
381 
382 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
383 {
384         unsigned int max = (1 << (recsize << 3)) - 1;
385 
386         if (len > max)
387                 return max;
388         return len;
389 }
390 EXPORT_SYMBOL(__kfifo_max_r);
391 
392 #define __KFIFO_PEEK(data, out, mask) \
393         ((data)[(out) & (mask)])
394 /*
395  * __kfifo_peek_n internal helper function for determinate the length of
396  * the next record in the fifo
397  */
398 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
399 {
400         unsigned int l;
401         unsigned int mask = fifo->mask;
402         unsigned char *data = fifo->data;
403 
404         l = __KFIFO_PEEK(data, fifo->out, mask);
405 
406         if (--recsize)
407                 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
408 
409         return l;
410 }
411 
412 #define __KFIFO_POKE(data, in, mask, val) \
413         ( \
414         (data)[(in) & (mask)] = (unsigned char)(val) \
415         )
416 
417 /*
418  * __kfifo_poke_n internal helper function for storeing the length of
419  * the record into the fifo
420  */
421 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
422 {
423         unsigned int mask = fifo->mask;
424         unsigned char *data = fifo->data;
425 
426         __KFIFO_POKE(data, fifo->in, mask, n);
427 
428         if (recsize > 1)
429                 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
430 }
431 
432 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
433 {
434         return __kfifo_peek_n(fifo, recsize);
435 }
436 EXPORT_SYMBOL(__kfifo_len_r);
437 
438 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
439                 unsigned int len, size_t recsize)
440 {
441         if (len + recsize > kfifo_unused(fifo))
442                 return 0;
443 
444         __kfifo_poke_n(fifo, len, recsize);
445 
446         kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
447         fifo->in += len + recsize;
448         return len;
449 }
450 EXPORT_SYMBOL(__kfifo_in_r);
451 
452 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
453         void *buf, unsigned int len, size_t recsize, unsigned int *n)
454 {
455         *n = __kfifo_peek_n(fifo, recsize);
456 
457         if (len > *n)
458                 len = *n;
459 
460         kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
461         return len;
462 }
463 
464 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
465                 unsigned int len, size_t recsize)
466 {
467         unsigned int n;
468 
469         if (fifo->in == fifo->out)
470                 return 0;
471 
472         return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
473 }
474 EXPORT_SYMBOL(__kfifo_out_peek_r);
475 
476 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
477                 unsigned int len, size_t recsize)
478 {
479         unsigned int n;
480 
481         if (fifo->in == fifo->out)
482                 return 0;
483 
484         len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
485         fifo->out += n + recsize;
486         return len;
487 }
488 EXPORT_SYMBOL(__kfifo_out_r);
489 
490 void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
491 {
492         unsigned int n;
493 
494         n = __kfifo_peek_n(fifo, recsize);
495         fifo->out += n + recsize;
496 }
497 EXPORT_SYMBOL(__kfifo_skip_r);
498 
499 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
500         unsigned long len, unsigned int *copied, size_t recsize)
501 {
502         unsigned long ret;
503 
504         len = __kfifo_max_r(len, recsize);
505 
506         if (len + recsize > kfifo_unused(fifo)) {
507                 *copied = 0;
508                 return 0;
509         }
510 
511         __kfifo_poke_n(fifo, len, recsize);
512 
513         ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
514         if (unlikely(ret)) {
515                 *copied = 0;
516                 return -EFAULT;
517         }
518         fifo->in += len + recsize;
519         return 0;
520 }
521 EXPORT_SYMBOL(__kfifo_from_user_r);
522 
523 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
524         unsigned long len, unsigned int *copied, size_t recsize)
525 {
526         unsigned long ret;
527         unsigned int n;
528 
529         if (fifo->in == fifo->out) {
530                 *copied = 0;
531                 return 0;
532         }
533 
534         n = __kfifo_peek_n(fifo, recsize);
535         if (len > n)
536                 len = n;
537 
538         ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
539         if (unlikely(ret)) {
540                 *copied = 0;
541                 return -EFAULT;
542         }
543         fifo->out += n + recsize;
544         return 0;
545 }
546 EXPORT_SYMBOL(__kfifo_to_user_r);
547 
548 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
549         struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
550 {
551         BUG_ON(!nents);
552 
553         len = __kfifo_max_r(len, recsize);
554 
555         if (len + recsize > kfifo_unused(fifo))
556                 return 0;
557 
558         return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
559 }
560 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
561 
562 void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
563         unsigned int len, size_t recsize)
564 {
565         len = __kfifo_max_r(len, recsize);
566         __kfifo_poke_n(fifo, len, recsize);
567         fifo->in += len + recsize;
568 }
569 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
570 
571 unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
572         struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
573 {
574         BUG_ON(!nents);
575 
576         len = __kfifo_max_r(len, recsize);
577 
578         if (len + recsize > fifo->in - fifo->out)
579                 return 0;
580 
581         return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
582 }
583 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
584 
585 void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
586 {
587         unsigned int len;
588 
589         len = __kfifo_peek_n(fifo, recsize);
590         fifo->out += len + recsize;
591 }
592 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
593 

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