kfifo.c

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    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 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 }
   68 EXPORT_SYMBOL(__kfifo_alloc);
   69 
   70 void __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 }
   79 EXPORT_SYMBOL(__kfifo_free);
   80 
   81 int __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 }
  102 EXPORT_SYMBOL(__kfifo_init);
  103 
  104 static 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 
  128 unsigned 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 }
  141 EXPORT_SYMBOL(__kfifo_in);
  142 
  143 static 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 
  167 unsigned 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 }
  179 EXPORT_SYMBOL(__kfifo_out_peek);
  180 
  181 unsigned 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 }
  188 EXPORT_SYMBOL(__kfifo_out);
  189 
  190 static 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 
  225 int __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 }
  249 EXPORT_SYMBOL(__kfifo_from_user);
  250 
  251 static 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 
  285 int __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 }
  308 EXPORT_SYMBOL(__kfifo_to_user);
  309 
  310 static 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 
  349 static 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 
  371 unsigned 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 }
  382 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
  383 
  384 unsigned 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 }
  395 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
  396 
  397 unsigned 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 }
  405 EXPORT_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  */
  413 static 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  */
  436 static 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 
  447 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
  448 {
  449         return __kfifo_peek_n(fifo, recsize);
  450 }
  451 EXPORT_SYMBOL(__kfifo_len_r);
  452 
  453 unsigned 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 }
  465 EXPORT_SYMBOL(__kfifo_in_r);
  466 
  467 static 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 
  479 unsigned 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 }
  489 EXPORT_SYMBOL(__kfifo_out_peek_r);
  490 
  491 unsigned 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 }
  503 EXPORT_SYMBOL(__kfifo_out_r);
  504 
  505 void __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 }
  512 EXPORT_SYMBOL(__kfifo_skip_r);
  513 
  514 int __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 }
  536 EXPORT_SYMBOL(__kfifo_from_user_r);
  537 
  538 int __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 }
  561 EXPORT_SYMBOL(__kfifo_to_user_r);
  562 
  563 unsigned 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 }
  576 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
  577 
  578 void __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 }
  585 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
  586 
  587 unsigned 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 }
  600 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
  601 
  602 void __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 }
  609 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
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This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.
FreeBSD/Linux Kernel Cross Reference sys/kernel/kfifo.c

FreeBSD/Linux Kernel Cross Reference
sys/kernel/kfifo.c
