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
  19 static struct crypto_shash *crct10dif_tfm;
  20 static struct static_key crct10dif_fallback __read_mostly;
  21
  22 __u16 crc_t10dif(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(0, buffer, len);
  32
  33         desc.shash.tfm = crct10dif_tfm;
  34         desc.shash.flags = 0;
  35         *(__u16 *)desc.ctx = 0;
  36
  37         err = crypto_shash_update(&desc.shash, buffer, len);
  38         BUG_ON(err);
  39
  40         return *(__u16 *)desc.ctx;
  41 }
  42 EXPORT_SYMBOL(crc_t10dif);
  43
  44 static int __init crc_t10dif_mod_init(void)
  45 {
  46         crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
  47         if (IS_ERR(crct10dif_tfm)) {
  48                 static_key_slow_inc(&crct10dif_fallback);
  49                 crct10dif_tfm = NULL;
  50         }
  51         return 0;
  52 }
  53
  54 static void __exit crc_t10dif_mod_fini(void)
  55 {
  56         crypto_free_shash(crct10dif_tfm);
  57 }
  58
  59 module_init(crc_t10dif_mod_init);
  60 module_exit(crc_t10dif_mod_fini);
  61
  62 MODULE_DESCRIPTION("T10 DIF CRC calculation");
  63 MODULE_LICENSE("GPL");
  64 MODULE_SOFTDEP("pre: crct10dif");