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