Root/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 */
33static inline unsigned int kfifo_unused(struct __kfifo *fifo)
34{
35    return (fifo->mask + 1) - (fifo->in - fifo->out);
36}
37
38int __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}
67EXPORT_SYMBOL(__kfifo_alloc);
68
69void __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}
78EXPORT_SYMBOL(__kfifo_free);
79
80int __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}
100EXPORT_SYMBOL(__kfifo_init);
101
102static 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
126unsigned 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}
139EXPORT_SYMBOL(__kfifo_in);
140
141static 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
165unsigned 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}
177EXPORT_SYMBOL(__kfifo_out_peek);
178
179unsigned 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}
186EXPORT_SYMBOL(__kfifo_out);
187
188static 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
223int __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}
247EXPORT_SYMBOL(__kfifo_from_user);
248
249static 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
283int __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}
306EXPORT_SYMBOL(__kfifo_to_user);
307
308static 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
347static 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
369unsigned 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}
380EXPORT_SYMBOL(__kfifo_dma_in_prepare);
381
382unsigned 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}
393EXPORT_SYMBOL(__kfifo_dma_out_prepare);
394
395unsigned 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}
403EXPORT_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 */
411static 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 */
434static 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
445unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
446{
447    return __kfifo_peek_n(fifo, recsize);
448}
449EXPORT_SYMBOL(__kfifo_len_r);
450
451unsigned 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}
463EXPORT_SYMBOL(__kfifo_in_r);
464
465static 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
477unsigned 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}
487EXPORT_SYMBOL(__kfifo_out_peek_r);
488
489unsigned 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}
501EXPORT_SYMBOL(__kfifo_out_r);
502
503void __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}
510EXPORT_SYMBOL(__kfifo_skip_r);
511
512int __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}
534EXPORT_SYMBOL(__kfifo_from_user_r);
535
536int __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}
559EXPORT_SYMBOL(__kfifo_to_user_r);
560
561unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
562    struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
563{
564    if (!nents)
565        BUG();
566
567    len = __kfifo_max_r(len, recsize);
568
569    if (len + recsize > kfifo_unused(fifo))
570        return 0;
571
572    return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
573}
574EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
575
576void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
577    unsigned int len, size_t recsize)
578{
579    len = __kfifo_max_r(len, recsize);
580    __kfifo_poke_n(fifo, len, recsize);
581    fifo->in += len + recsize;
582}
583EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
584
585unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
586    struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
587{
588    if (!nents)
589        BUG();
590
591    len = __kfifo_max_r(len, recsize);
592
593    if (len + recsize > fifo->in - fifo->out)
594        return 0;
595
596    return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
597}
598EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
599
600void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
601{
602    unsigned int len;
603
604    len = __kfifo_peek_n(fifo, recsize);
605    fifo->out += len + recsize;
606}
607EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
608

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