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;
 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;
 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         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 }
 574 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
 575
 576 void __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 }
 583 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
 584
 585 unsigned 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 }
 598 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
 599
 600 void __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 }
 607 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);