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 up 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_array(esize, size, 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         if (!is_power_of_2(size))
  86                 size = rounddown_pow_of_two(size);
  87
  88         fifo->in = 0;
  89         fifo->out = 0;
  90         fifo->esize = esize;
  91         fifo->data = buffer;
  92
  93         if (size < 2) {
  94                 fifo->mask = 0;
  95                 return -EINVAL;
  96         }
  97         fifo->mask = size - 1;
  98
  99         return 0;
 100 }
 101 EXPORT_SYMBOL(__kfifo_init);
 102
 103 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
 104                 unsigned int len, unsigned int off)
 105 {
 106         unsigned int size = fifo->mask + 1;
 107         unsigned int esize = fifo->esize;
 108         unsigned int l;
 109
 110         off &= fifo->mask;
 111         if (esize != 1) {
 112                 off *= esize;
 113                 size *= esize;
 114                 len *= esize;
 115         }
 116         l = min(len, size - off);
 117
 118         memcpy(fifo->data + off, src, l);
 119         memcpy(fifo->data, src + l, len - l);
 120         /*
 121          * make sure that the data in the fifo is up to date before
 122          * incrementing the fifo->in index counter
 123          */
 124         smp_wmb();
 125 }
 126
 127 unsigned int __kfifo_in(struct __kfifo *fifo,
 128                 const void *buf, unsigned int len)
 129 {
 130         unsigned int l;
 131
 132         l = kfifo_unused(fifo);
 133         if (len > l)
 134                 len = l;
 135
 136         kfifo_copy_in(fifo, buf, len, fifo->in);
 137         fifo->in += len;
 138         return len;
 139 }
 140 EXPORT_SYMBOL(__kfifo_in);
 141
 142 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
 143                 unsigned int len, unsigned int off)
 144 {
 145         unsigned int size = fifo->mask + 1;
 146         unsigned int esize = fifo->esize;
 147         unsigned int l;
 148
 149         off &= fifo->mask;
 150         if (esize != 1) {
 151                 off *= esize;
 152                 size *= esize;
 153                 len *= esize;
 154         }
 155         l = min(len, size - off);
 156
 157         memcpy(dst, fifo->data + off, l);
 158         memcpy(dst + l, fifo->data, len - l);
 159         /*
 160          * make sure that the data is copied before
 161          * incrementing the fifo->out index counter
 162          */
 163         smp_wmb();
 164 }
 165
 166 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
 167                 void *buf, unsigned int len)
 168 {
 169         unsigned int l;
 170
 171         l = fifo->in - fifo->out;
 172         if (len > l)
 173                 len = l;
 174
 175         kfifo_copy_out(fifo, buf, len, fifo->out);
 176         return len;
 177 }
 178 EXPORT_SYMBOL(__kfifo_out_peek);
 179
 180 unsigned int __kfifo_out(struct __kfifo *fifo,
 181                 void *buf, unsigned int len)
 182 {
 183         len = __kfifo_out_peek(fifo, buf, len);
 184         fifo->out += len;
 185         return len;
 186 }
 187 EXPORT_SYMBOL(__kfifo_out);
 188
 189 static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
 190         const void __user *from, unsigned int len, unsigned int off,
 191         unsigned int *copied)
 192 {
 193         unsigned int size = fifo->mask + 1;
 194         unsigned int esize = fifo->esize;
 195         unsigned int l;
 196         unsigned long ret;
 197
 198         off &= fifo->mask;
 199         if (esize != 1) {
 200                 off *= esize;
 201                 size *= esize;
 202                 len *= esize;
 203         }
 204         l = min(len, size - off);
 205
 206         ret = copy_from_user(fifo->data + off, from, l);
 207         if (unlikely(ret))
 208                 ret = DIV_ROUND_UP(ret + len - l, esize);
 209         else {
 210                 ret = copy_from_user(fifo->data, from + l, len - l);
 211                 if (unlikely(ret))
 212                         ret = DIV_ROUND_UP(ret, esize);
 213         }
 214         /*
 215          * make sure that the data in the fifo is up to date before
 216          * incrementing the fifo->in index counter
 217          */
 218         smp_wmb();
 219         *copied = len - ret * esize;
 220         /* return the number of elements which are not copied */
 221         return ret;
 222 }
 223
 224 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
 225                 unsigned long len, unsigned int *copied)
 226 {
 227         unsigned int l;
 228         unsigned long ret;
 229         unsigned int esize = fifo->esize;
 230         int err;
 231
 232         if (esize != 1)
 233                 len /= esize;
 234
 235         l = kfifo_unused(fifo);
 236         if (len > l)
 237                 len = l;
 238
 239         ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
 240         if (unlikely(ret)) {
 241                 len -= ret;
 242                 err = -EFAULT;
 243         } else
 244                 err = 0;
 245         fifo->in += len;
 246         return err;
 247 }
 248 EXPORT_SYMBOL(__kfifo_from_user);
 249
 250 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
 251                 unsigned int len, unsigned int off, unsigned int *copied)
 252 {
 253         unsigned int l;
 254         unsigned long ret;
 255         unsigned int size = fifo->mask + 1;
 256         unsigned int esize = fifo->esize;
 257
 258         off &= fifo->mask;
 259         if (esize != 1) {
 260                 off *= esize;
 261                 size *= esize;
 262                 len *= esize;
 263         }
 264         l = min(len, size - off);
 265
 266         ret = copy_to_user(to, fifo->data + off, l);
 267         if (unlikely(ret))
 268                 ret = DIV_ROUND_UP(ret + len - l, esize);
 269         else {
 270                 ret = copy_to_user(to + l, fifo->data, len - l);
 271                 if (unlikely(ret))
 272                         ret = DIV_ROUND_UP(ret, esize);
 273         }
 274         /*
 275          * make sure that the data is copied before
 276          * incrementing the fifo->out index counter
 277          */
 278         smp_wmb();
 279         *copied = len - ret * esize;
 280         /* return the number of elements which are not copied */
 281         return ret;
 282 }
 283
 284 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
 285                 unsigned long len, unsigned int *copied)
 286 {
 287         unsigned int l;
 288         unsigned long ret;
 289         unsigned int esize = fifo->esize;
 290         int err;
 291
 292         if (esize != 1)
 293                 len /= esize;
 294
 295         l = fifo->in - fifo->out;
 296         if (len > l)
 297                 len = l;
 298         ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
 299         if (unlikely(ret)) {
 300                 len -= ret;
 301                 err = -EFAULT;
 302         } else
 303                 err = 0;
 304         fifo->out += len;
 305         return err;
 306 }
 307 EXPORT_SYMBOL(__kfifo_to_user);
 308
 309 static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
 310                 int nents, unsigned int len)
 311 {
 312         int n;
 313         unsigned int l;
 314         unsigned int off;
 315         struct page *page;
 316
 317         if (!nents)
 318                 return 0;
 319
 320         if (!len)
 321                 return 0;
 322
 323         n = 0;
 324         page = virt_to_page(buf);
 325         off = offset_in_page(buf);
 326         l = 0;
 327
 328         while (len >= l + PAGE_SIZE - off) {
 329                 struct page *npage;
 330
 331                 l += PAGE_SIZE;
 332                 buf += PAGE_SIZE;
 333                 npage = virt_to_page(buf);
 334                 if (page_to_phys(page) != page_to_phys(npage) - l) {
 335                         sg_set_page(sgl, page, l - off, off);
 336                         sgl = sg_next(sgl);
 337                         if (++n == nents || sgl == NULL)
 338                                 return n;
 339                         page = npage;
 340                         len -= l - off;
 341                         l = off = 0;
 342                 }
 343         }
 344         sg_set_page(sgl, page, len, off);
 345         return n + 1;
 346 }
 347
 348 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
 349                 int nents, unsigned int len, unsigned int off)
 350 {
 351         unsigned int size = fifo->mask + 1;
 352         unsigned int esize = fifo->esize;
 353         unsigned int l;
 354         unsigned int n;
 355
 356         off &= fifo->mask;
 357         if (esize != 1) {
 358                 off *= esize;
 359                 size *= esize;
 360                 len *= esize;
 361         }
 362         l = min(len, size - off);
 363
 364         n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
 365         n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
 366
 367         return n;
 368 }
 369
 370 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
 371                 struct scatterlist *sgl, int nents, unsigned int len)
 372 {
 373         unsigned int l;
 374
 375         l = kfifo_unused(fifo);
 376         if (len > l)
 377                 len = l;
 378
 379         return setup_sgl(fifo, sgl, nents, len, fifo->in);
 380 }
 381 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
 382
 383 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
 384                 struct scatterlist *sgl, int nents, unsigned int len)
 385 {
 386         unsigned int l;
 387
 388         l = fifo->in - fifo->out;
 389         if (len > l)
 390                 len = l;
 391
 392         return setup_sgl(fifo, sgl, nents, len, fifo->out);
 393 }
 394 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
 395
 396 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
 397 {
 398         unsigned int max = (1 << (recsize << 3)) - 1;
 399
 400         if (len > max)
 401                 return max;
 402         return len;
 403 }
 404 EXPORT_SYMBOL(__kfifo_max_r);
 405
 406 #define __KFIFO_PEEK(data, out, mask) \
 407         ((data)[(out) & (mask)])
 408 /*
 409  * __kfifo_peek_n internal helper function for determinate the length of
 410  * the next record in the fifo
 411  */
 412 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
 413 {
 414         unsigned int l;
 415         unsigned int mask = fifo->mask;
 416         unsigned char *data = fifo->data;
 417
 418         l = __KFIFO_PEEK(data, fifo->out, mask);
 419
 420         if (--recsize)
 421                 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
 422
 423         return l;
 424 }
 425
 426 #define __KFIFO_POKE(data, in, mask, val) \
 427         ( \
 428         (data)[(in) & (mask)] = (unsigned char)(val) \
 429         )
 430
 431 /*
 432  * __kfifo_poke_n internal helper function for storeing the length of
 433  * the record into the fifo
 434  */
 435 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
 436 {
 437         unsigned int mask = fifo->mask;
 438         unsigned char *data = fifo->data;
 439
 440         __KFIFO_POKE(data, fifo->in, mask, n);
 441
 442         if (recsize > 1)
 443                 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
 444 }
 445
 446 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
 447 {
 448         return __kfifo_peek_n(fifo, recsize);
 449 }
 450 EXPORT_SYMBOL(__kfifo_len_r);
 451
 452 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
 453                 unsigned int len, size_t recsize)
 454 {
 455         if (len + recsize > kfifo_unused(fifo))
 456                 return 0;
 457
 458         __kfifo_poke_n(fifo, len, recsize);
 459
 460         kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
 461         fifo->in += len + recsize;
 462         return len;
 463 }
 464 EXPORT_SYMBOL(__kfifo_in_r);
 465
 466 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
 467         void *buf, unsigned int len, size_t recsize, unsigned int *n)
 468 {
 469         *n = __kfifo_peek_n(fifo, recsize);
 470
 471         if (len > *n)
 472                 len = *n;
 473
 474         kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
 475         return len;
 476 }
 477
 478 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
 479                 unsigned int len, size_t recsize)
 480 {
 481         unsigned int n;
 482
 483         if (fifo->in == fifo->out)
 484                 return 0;
 485
 486         return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
 487 }
 488 EXPORT_SYMBOL(__kfifo_out_peek_r);
 489
 490 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
 491                 unsigned int len, size_t recsize)
 492 {
 493         unsigned int n;
 494
 495         if (fifo->in == fifo->out)
 496                 return 0;
 497
 498         len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
 499         fifo->out += n + recsize;
 500         return len;
 501 }
 502 EXPORT_SYMBOL(__kfifo_out_r);
 503
 504 void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
 505 {
 506         unsigned int n;
 507
 508         n = __kfifo_peek_n(fifo, recsize);
 509         fifo->out += n + recsize;
 510 }
 511 EXPORT_SYMBOL(__kfifo_skip_r);
 512
 513 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
 514         unsigned long len, unsigned int *copied, size_t recsize)
 515 {
 516         unsigned long ret;
 517
 518         len = __kfifo_max_r(len, recsize);
 519
 520         if (len + recsize > kfifo_unused(fifo)) {
 521                 *copied = 0;
 522                 return 0;
 523         }
 524
 525         __kfifo_poke_n(fifo, len, recsize);
 526
 527         ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
 528         if (unlikely(ret)) {
 529                 *copied = 0;
 530                 return -EFAULT;
 531         }
 532         fifo->in += len + recsize;
 533         return 0;
 534 }
 535 EXPORT_SYMBOL(__kfifo_from_user_r);
 536
 537 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
 538         unsigned long len, unsigned int *copied, size_t recsize)
 539 {
 540         unsigned long ret;
 541         unsigned int n;
 542
 543         if (fifo->in == fifo->out) {
 544                 *copied = 0;
 545                 return 0;
 546         }
 547
 548         n = __kfifo_peek_n(fifo, recsize);
 549         if (len > n)
 550                 len = n;
 551
 552         ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
 553         if (unlikely(ret)) {
 554                 *copied = 0;
 555                 return -EFAULT;
 556         }
 557         fifo->out += n + recsize;
 558         return 0;
 559 }
 560 EXPORT_SYMBOL(__kfifo_to_user_r);
 561
 562 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
 563         struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
 564 {
 565         BUG_ON(!nents);
 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         BUG_ON(!nents);
 589
 590         len = __kfifo_max_r(len, recsize);
 591
 592         if (len + recsize > fifo->in - fifo->out)
 593                 return 0;
 594
 595         return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
 596 }
 597 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
 598
 599 void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
 600 {
 601         unsigned int len;
 602
 603         len = __kfifo_peek_n(fifo, recsize);
 604         fifo->out += len + recsize;
 605 }
 606 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);