LXR linux/lib/crc-t10dif.c

   1/*
   2 * T10 Data Integrity Field CRC16 calculation
   3 *
   4 * Copyright (c) 2007 Oracle Corporation.  All rights reserved.
   5 * Written by Martin K. Petersen <martin.petersen@oracle.com>
   6 *
   7 * This source code is licensed under the GNU General Public License,
   8 * Version 2. See the file COPYING for more details.
   9 */
  10
  11#include <linux/types.h>
  12#include <linux/module.h>
  13#include <linux/crc-t10dif.h>
  14#include <linux/err.h>
  15#include <linux/init.h>
  16#include <crypto/hash.h>
  17#include <linux/static_key.h>
  18
  19static struct crypto_shash *crct10dif_tfm;
  20static struct static_key crct10dif_fallback __read_mostly;
  21
  22__u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
  23{
  24        struct {
  25                struct shash_desc shash;
  26                char ctx[2];
  27        } desc;
  28        int err;
  29
  30        if (static_key_false(&crct10dif_fallback))
  31                return crc_t10dif_generic(crc, buffer, len);
  32
  33        desc.shash.tfm = crct10dif_tfm;
  34        desc.shash.flags = 0;
  35        *(__u16 *)desc.ctx = crc;
  36
  37        err = crypto_shash_update(&desc.shash, buffer, len);
  38        BUG_ON(err);
  39
  40        return *(__u16 *)desc.ctx;
  41}
  42EXPORT_SYMBOL(crc_t10dif_update);
  43
  44__u16 crc_t10dif(const unsigned char *buffer, size_t len)
  45{
  46        return crc_t10dif_update(0, buffer, len);
  47}
  48EXPORT_SYMBOL(crc_t10dif);
  49
  50static int __init crc_t10dif_mod_init(void)
  51{
  52        crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
  53        if (IS_ERR(crct10dif_tfm)) {
  54                static_key_slow_inc(&crct10dif_fallback);
  55                crct10dif_tfm = NULL;
  56        }
  57        return 0;
  58}
  59
  60static void __exit crc_t10dif_mod_fini(void)
  61{
  62        crypto_free_shash(crct10dif_tfm);
  63}
  64
  65module_init(crc_t10dif_mod_init);
  66module_exit(crc_t10dif_mod_fini);
  67
  68MODULE_DESCRIPTION("T10 DIF CRC calculation");
  69MODULE_LICENSE("GPL");
  70MODULE_SOFTDEP("pre: crct10dif");
  71