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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 
 19 static struct crypto_shash *crct10dif_tfm;
 20 static 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 }
 42 EXPORT_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 }
 48 EXPORT_SYMBOL(crc_t10dif);
 49 
 50 static 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 
 60 static void __exit crc_t10dif_mod_fini(void)
 61 {
 62         crypto_free_shash(crct10dif_tfm);
 63 }
 64 
 65 module_init(crc_t10dif_mod_init);
 66 module_exit(crc_t10dif_mod_fini);
 67 
 68 MODULE_DESCRIPTION("T10 DIF CRC calculation");
 69 MODULE_LICENSE("GPL");
 70 MODULE_SOFTDEP("pre: crct10dif");
 71 

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