LXR linux/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 */
  19static inline unsigned int kfifo_unused(struct __kfifo *fifo)
  20{
  21        return (fifo->mask + 1) - (fifo->in - fifo->out);
  22}
  23
  24int __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}
  53EXPORT_SYMBOL(__kfifo_alloc);
  54
  55void __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}
  64EXPORT_SYMBOL(__kfifo_free);
  65
  66int __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}
  86EXPORT_SYMBOL(__kfifo_init);
  87
  88static 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
 112unsigned 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}
 125EXPORT_SYMBOL(__kfifo_in);
 126
 127static 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
 151unsigned 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}
 163EXPORT_SYMBOL(__kfifo_out_peek);
 164
 165unsigned 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}
 172EXPORT_SYMBOL(__kfifo_out);
 173
 174static 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
 209int __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}
 233EXPORT_SYMBOL(__kfifo_from_user);
 234
 235static 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
 269int __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}
 292EXPORT_SYMBOL(__kfifo_to_user);
 293
 294static 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
 333static 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
 355unsigned 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}
 366EXPORT_SYMBOL(__kfifo_dma_in_prepare);
 367
 368unsigned 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}
 379EXPORT_SYMBOL(__kfifo_dma_out_prepare);
 380
 381unsigned 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}
 389EXPORT_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 */
 397static 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 */
 420static 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
 431unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
 432{
 433        return __kfifo_peek_n(fifo, recsize);
 434}
 435EXPORT_SYMBOL(__kfifo_len_r);
 436
 437unsigned 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}
 449EXPORT_SYMBOL(__kfifo_in_r);
 450
 451static 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
 463unsigned 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}
 473EXPORT_SYMBOL(__kfifo_out_peek_r);
 474
 475unsigned 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}
 487EXPORT_SYMBOL(__kfifo_out_r);
 488
 489void __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}
 496EXPORT_SYMBOL(__kfifo_skip_r);
 497
 498int __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}
 520EXPORT_SYMBOL(__kfifo_from_user_r);
 521
 522int __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}
 545EXPORT_SYMBOL(__kfifo_to_user_r);
 546
 547unsigned 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}
 559EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
 560
 561void __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}
 568EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
 569
 570unsigned 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}
 582EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
 583
 584void __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}
 591EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
 592