lib/kfifo.c

   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 storing 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);