linux/kernel/kfifo.c
<<
>>
Prefs
   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 */
  33static inline unsigned int kfifo_unused(struct __kfifo *fifo)
  34{
  35        return (fifo->mask + 1) - (fifo->in - fifo->out);
  36}
  37
  38int __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        if (!is_power_of_2(size))
  46                size = rounddown_pow_of_two(size);
  47
  48        fifo->in = 0;
  49        fifo->out = 0;
  50        fifo->esize = esize;
  51
  52        if (size < 2) {
  53                fifo->data = NULL;
  54                fifo->mask = 0;
  55                return -EINVAL;
  56        }
  57
  58        fifo->data = kmalloc(size * esize, gfp_mask);
  59
  60        if (!fifo->data) {
  61                fifo->mask = 0;
  62                return -ENOMEM;
  63        }
  64        fifo->mask = size - 1;
  65
  66        return 0;
  67}
  68EXPORT_SYMBOL(__kfifo_alloc);
  69
  70void __kfifo_free(struct __kfifo *fifo)
  71{
  72        kfree(fifo->data);
  73        fifo->in = 0;
  74        fifo->out = 0;
  75        fifo->esize = 0;
  76        fifo->data = NULL;
  77        fifo->mask = 0;
  78}
  79EXPORT_SYMBOL(__kfifo_free);
  80
  81int __kfifo_init(struct __kfifo *fifo, void *buffer,
  82                unsigned int size, size_t esize)
  83{
  84        size /= esize;
  85
  86        if (!is_power_of_2(size))
  87                size = rounddown_pow_of_two(size);
  88
  89        fifo->in = 0;
  90        fifo->out = 0;
  91        fifo->esize = esize;
  92        fifo->data = buffer;
  93
  94        if (size < 2) {
  95                fifo->mask = 0;
  96                return -EINVAL;
  97        }
  98        fifo->mask = size - 1;
  99
 100        return 0;
 101}
 102EXPORT_SYMBOL(__kfifo_init);
 103
 104static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
 105                unsigned int len, unsigned int off)
 106{
 107        unsigned int size = fifo->mask + 1;
 108        unsigned int esize = fifo->esize;
 109        unsigned int l;
 110
 111        off &= fifo->mask;
 112        if (esize != 1) {
 113                off *= esize;
 114                size *= esize;
 115                len *= esize;
 116        }
 117        l = min(len, size - off);
 118
 119        memcpy(fifo->data + off, src, l);
 120        memcpy(fifo->data, src + l, len - l);
 121        /*
 122         * make sure that the data in the fifo is up to date before
 123         * incrementing the fifo->in index counter
 124         */
 125        smp_wmb();
 126}
 127
 128unsigned int __kfifo_in(struct __kfifo *fifo,
 129                const void *buf, unsigned int len)
 130{
 131        unsigned int l;
 132
 133        l = kfifo_unused(fifo);
 134        if (len > l)
 135                len = l;
 136
 137        kfifo_copy_in(fifo, buf, len, fifo->in);
 138        fifo->in += len;
 139        return len;
 140}
 141EXPORT_SYMBOL(__kfifo_in);
 142
 143static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
 144                unsigned int len, unsigned int off)
 145{
 146        unsigned int size = fifo->mask + 1;
 147        unsigned int esize = fifo->esize;
 148        unsigned int l;
 149
 150        off &= fifo->mask;
 151        if (esize != 1) {
 152                off *= esize;
 153                size *= esize;
 154                len *= esize;
 155        }
 156        l = min(len, size - off);
 157
 158        memcpy(dst, fifo->data + off, l);
 159        memcpy(dst + l, fifo->data, len - l);
 160        /*
 161         * make sure that the data is copied before
 162         * incrementing the fifo->out index counter
 163         */
 164        smp_wmb();
 165}
 166
 167unsigned int __kfifo_out_peek(struct __kfifo *fifo,
 168                void *buf, unsigned int len)
 169{
 170        unsigned int l;
 171
 172        l = fifo->in - fifo->out;
 173        if (len > l)
 174                len = l;
 175
 176        kfifo_copy_out(fifo, buf, len, fifo->out);
 177        return len;
 178}
 179EXPORT_SYMBOL(__kfifo_out_peek);
 180
 181unsigned int __kfifo_out(struct __kfifo *fifo,
 182                void *buf, unsigned int len)
 183{
 184        len = __kfifo_out_peek(fifo, buf, len);
 185        fifo->out += len;
 186        return len;
 187}
 188EXPORT_SYMBOL(__kfifo_out);
 189
 190static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
 191        const void __user *from, unsigned int len, unsigned int off,
 192        unsigned int *copied)
 193{
 194        unsigned int size = fifo->mask + 1;
 195        unsigned int esize = fifo->esize;
 196        unsigned int l;
 197        unsigned long ret;
 198
 199        off &= fifo->mask;
 200        if (esize != 1) {
 201                off *= esize;
 202                size *= esize;
 203                len *= esize;
 204        }
 205        l = min(len, size - off);
 206
 207        ret = copy_from_user(fifo->data + off, from, l);
 208        if (unlikely(ret))
 209                ret = DIV_ROUND_UP(ret + len - l, esize);
 210        else {
 211                ret = copy_from_user(fifo->data, from + l, len - l);
 212                if (unlikely(ret))
 213                        ret = DIV_ROUND_UP(ret, esize);
 214        }
 215        /*
 216         * make sure that the data in the fifo is up to date before
 217         * incrementing the fifo->in index counter
 218         */
 219        smp_wmb();
 220        *copied = len - ret;
 221        /* return the number of elements which are not copied */
 222        return ret;
 223}
 224
 225int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
 226                unsigned long len, unsigned int *copied)
 227{
 228        unsigned int l;
 229        unsigned long ret;
 230        unsigned int esize = fifo->esize;
 231        int err;
 232
 233        if (esize != 1)
 234                len /= esize;
 235
 236        l = kfifo_unused(fifo);
 237        if (len > l)
 238                len = l;
 239
 240        ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
 241        if (unlikely(ret)) {
 242                len -= ret;
 243                err = -EFAULT;
 244        } else
 245                err = 0;
 246        fifo->in += len;
 247        return err;
 248}
 249EXPORT_SYMBOL(__kfifo_from_user);
 250
 251static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
 252                unsigned int len, unsigned int off, unsigned int *copied)
 253{
 254        unsigned int l;
 255        unsigned long ret;
 256        unsigned int size = fifo->mask + 1;
 257        unsigned int esize = fifo->esize;
 258
 259        off &= fifo->mask;
 260        if (esize != 1) {
 261                off *= esize;
 262                size *= esize;
 263                len *= esize;
 264        }
 265        l = min(len, size - off);
 266
 267        ret = copy_to_user(to, fifo->data + off, l);
 268        if (unlikely(ret))
 269                ret = DIV_ROUND_UP(ret + len - l, esize);
 270        else {
 271                ret = copy_to_user(to + l, fifo->data, len - l);
 272                if (unlikely(ret))
 273                        ret = DIV_ROUND_UP(ret, esize);
 274        }
 275        /*
 276         * make sure that the data is copied before
 277         * incrementing the fifo->out index counter
 278         */
 279        smp_wmb();
 280        *copied = len - ret;
 281        /* return the number of elements which are not copied */
 282        return ret;
 283}
 284
 285int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
 286                unsigned long len, unsigned int *copied)
 287{
 288        unsigned int l;
 289        unsigned long ret;
 290        unsigned int esize = fifo->esize;
 291        int err;
 292
 293        if (esize != 1)
 294                len /= esize;
 295
 296        l = fifo->in - fifo->out;
 297        if (len > l)
 298                len = l;
 299        ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
 300        if (unlikely(ret)) {
 301                len -= ret;
 302                err = -EFAULT;
 303        } else
 304                err = 0;
 305        fifo->out += len;
 306        return err;
 307}
 308EXPORT_SYMBOL(__kfifo_to_user);
 309
 310static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
 311                int nents, unsigned int len)
 312{
 313        int n;
 314        unsigned int l;
 315        unsigned int off;
 316        struct page *page;
 317
 318        if (!nents)
 319                return 0;
 320
 321        if (!len)
 322                return 0;
 323
 324        n = 0;
 325        page = virt_to_page(buf);
 326        off = offset_in_page(buf);
 327        l = 0;
 328
 329        while (len >= l + PAGE_SIZE - off) {
 330                struct page *npage;
 331
 332                l += PAGE_SIZE;
 333                buf += PAGE_SIZE;
 334                npage = virt_to_page(buf);
 335                if (page_to_phys(page) != page_to_phys(npage) - l) {
 336                        sg_set_page(sgl, page, l - off, off);
 337                        sgl = sg_next(sgl);
 338                        if (++n == nents || sgl == NULL)
 339                                return n;
 340                        page = npage;
 341                        len -= l - off;
 342                        l = off = 0;
 343                }
 344        }
 345        sg_set_page(sgl, page, len, off);
 346        return n + 1;
 347}
 348
 349static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
 350                int nents, unsigned int len, unsigned int off)
 351{
 352        unsigned int size = fifo->mask + 1;
 353        unsigned int esize = fifo->esize;
 354        unsigned int l;
 355        unsigned int n;
 356
 357        off &= fifo->mask;
 358        if (esize != 1) {
 359                off *= esize;
 360                size *= esize;
 361                len *= esize;
 362        }
 363        l = min(len, size - off);
 364
 365        n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
 366        n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
 367
 368        return n;
 369}
 370
 371unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
 372                struct scatterlist *sgl, int nents, unsigned int len)
 373{
 374        unsigned int l;
 375
 376        l = kfifo_unused(fifo);
 377        if (len > l)
 378                len = l;
 379
 380        return setup_sgl(fifo, sgl, nents, len, fifo->in);
 381}
 382EXPORT_SYMBOL(__kfifo_dma_in_prepare);
 383
 384unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
 385                struct scatterlist *sgl, int nents, unsigned int len)
 386{
 387        unsigned int l;
 388
 389        l = fifo->in - fifo->out;
 390        if (len > l)
 391                len = l;
 392
 393        return setup_sgl(fifo, sgl, nents, len, fifo->out);
 394}
 395EXPORT_SYMBOL(__kfifo_dma_out_prepare);
 396
 397unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
 398{
 399        unsigned int max = (1 << (recsize << 3)) - 1;
 400
 401        if (len > max)
 402                return max;
 403        return len;
 404}
 405EXPORT_SYMBOL(__kfifo_max_r);
 406
 407#define __KFIFO_PEEK(data, out, mask) \
 408        ((data)[(out) & (mask)])
 409/*
 410 * __kfifo_peek_n internal helper function for determinate the length of
 411 * the next record in the fifo
 412 */
 413static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
 414{
 415        unsigned int l;
 416        unsigned int mask = fifo->mask;
 417        unsigned char *data = fifo->data;
 418
 419        l = __KFIFO_PEEK(data, fifo->out, mask);
 420
 421        if (--recsize)
 422                l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
 423
 424        return l;
 425}
 426
 427#define __KFIFO_POKE(data, in, mask, val) \
 428        ( \
 429        (data)[(in) & (mask)] = (unsigned char)(val) \
 430        )
 431
 432/*
 433 * __kfifo_poke_n internal helper function for storeing the length of
 434 * the record into the fifo
 435 */
 436static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
 437{
 438        unsigned int mask = fifo->mask;
 439        unsigned char *data = fifo->data;
 440
 441        __KFIFO_POKE(data, fifo->in, mask, n);
 442
 443        if (recsize > 1)
 444                __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
 445}
 446
 447unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
 448{
 449        return __kfifo_peek_n(fifo, recsize);
 450}
 451EXPORT_SYMBOL(__kfifo_len_r);
 452
 453unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
 454                unsigned int len, size_t recsize)
 455{
 456        if (len + recsize > kfifo_unused(fifo))
 457                return 0;
 458
 459        __kfifo_poke_n(fifo, len, recsize);
 460
 461        kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
 462        fifo->in += len + recsize;
 463        return len;
 464}
 465EXPORT_SYMBOL(__kfifo_in_r);
 466
 467static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
 468        void *buf, unsigned int len, size_t recsize, unsigned int *n)
 469{
 470        *n = __kfifo_peek_n(fifo, recsize);
 471
 472        if (len > *n)
 473                len = *n;
 474
 475        kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
 476        return len;
 477}
 478
 479unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
 480                unsigned int len, size_t recsize)
 481{
 482        unsigned int n;
 483
 484        if (fifo->in == fifo->out)
 485                return 0;
 486
 487        return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
 488}
 489EXPORT_SYMBOL(__kfifo_out_peek_r);
 490
 491unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
 492                unsigned int len, size_t recsize)
 493{
 494        unsigned int n;
 495
 496        if (fifo->in == fifo->out)
 497                return 0;
 498
 499        len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
 500        fifo->out += n + recsize;
 501        return len;
 502}
 503EXPORT_SYMBOL(__kfifo_out_r);
 504
 505void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
 506{
 507        unsigned int n;
 508
 509        n = __kfifo_peek_n(fifo, recsize);
 510        fifo->out += n + recsize;
 511}
 512EXPORT_SYMBOL(__kfifo_skip_r);
 513
 514int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
 515        unsigned long len, unsigned int *copied, size_t recsize)
 516{
 517        unsigned long ret;
 518
 519        len = __kfifo_max_r(len, recsize);
 520
 521        if (len + recsize > kfifo_unused(fifo)) {
 522                *copied = 0;
 523                return 0;
 524        }
 525
 526        __kfifo_poke_n(fifo, len, recsize);
 527
 528        ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
 529        if (unlikely(ret)) {
 530                *copied = 0;
 531                return -EFAULT;
 532        }
 533        fifo->in += len + recsize;
 534        return 0;
 535}
 536EXPORT_SYMBOL(__kfifo_from_user_r);
 537
 538int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
 539        unsigned long len, unsigned int *copied, size_t recsize)
 540{
 541        unsigned long ret;
 542        unsigned int n;
 543
 544        if (fifo->in == fifo->out) {
 545                *copied = 0;
 546                return 0;
 547        }
 548
 549        n = __kfifo_peek_n(fifo, recsize);
 550        if (len > n)
 551                len = n;
 552
 553        ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
 554        if (unlikely(ret)) {
 555                *copied = 0;
 556                return -EFAULT;
 557        }
 558        fifo->out += n + recsize;
 559        return 0;
 560}
 561EXPORT_SYMBOL(__kfifo_to_user_r);
 562
 563unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
 564        struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
 565{
 566        if (!nents)
 567                BUG();
 568
 569        len = __kfifo_max_r(len, recsize);
 570
 571        if (len + recsize > kfifo_unused(fifo))
 572                return 0;
 573
 574        return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
 575}
 576EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
 577
 578void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
 579        unsigned int len, size_t recsize)
 580{
 581        len = __kfifo_max_r(len, recsize);
 582        __kfifo_poke_n(fifo, len, recsize);
 583        fifo->in += len + recsize;
 584}
 585EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
 586
 587unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
 588        struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
 589{
 590        if (!nents)
 591                BUG();
 592
 593        len = __kfifo_max_r(len, recsize);
 594
 595        if (len + recsize > fifo->in - fifo->out)
 596                return 0;
 597
 598        return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
 599}
 600EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
 601
 602void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
 603{
 604        unsigned int len;
 605
 606        len = __kfifo_peek_n(fifo, recsize);
 607        fifo->out += len + recsize;
 608}
 609EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
 610
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.