Root/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(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}
42EXPORT_SYMBOL(crc_t10dif);
43
44static 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
54static void __exit crc_t10dif_mod_fini(void)
55{
56    crypto_free_shash(crct10dif_tfm);
57}
58
59module_init(crc_t10dif_mod_init);
60module_exit(crc_t10dif_mod_fini);
61
62MODULE_DESCRIPTION("T10 DIF CRC calculation");
63MODULE_LICENSE("GPL");
64MODULE_SOFTDEP("pre: crct10dif");
65

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