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877b5691f2
The flags field in 'struct shash_desc' never actually does anything. The only ostensibly supported flag is CRYPTO_TFM_REQ_MAY_SLEEP. However, no shash algorithm ever sleeps, making this flag a no-op. With this being the case, inevitably some users who can't sleep wrongly pass MAY_SLEEP. These would all need to be fixed if any shash algorithm actually started sleeping. For example, the shash_ahash_*() functions, which wrap a shash algorithm with the ahash API, pass through MAY_SLEEP from the ahash API to the shash API. However, the shash functions are called under kmap_atomic(), so actually they're assumed to never sleep. Even if it turns out that some users do need preemption points while hashing large buffers, we could easily provide a helper function crypto_shash_update_large() which divides the data into smaller chunks and calls crypto_shash_update() and cond_resched() for each chunk. It's not necessary to have a flag in 'struct shash_desc', nor is it necessary to make individual shash algorithms aware of this at all. Therefore, remove shash_desc::flags, and document that the crypto_shash_*() functions can be called from any context. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
/*
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* CRC32C
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*@Article{castagnoli-crc,
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* author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
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* title = {{Optimization of Cyclic Redundancy-Check Codes with 24
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* and 32 Parity Bits}},
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* journal = IEEE Transactions on Communication,
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* year = {1993},
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* volume = {41},
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* number = {6},
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* pages = {},
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* month = {June},
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*}
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* Used by the iSCSI driver, possibly others, and derived from the
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* the iscsi-crc.c module of the linux-iscsi driver at
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* http://linux-iscsi.sourceforge.net.
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*
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* Following the example of lib/crc32, this function is intended to be
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* flexible and useful for all users. Modules that currently have their
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* own crc32c, but hopefully may be able to use this one are:
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* net/sctp (please add all your doco to here if you change to
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* use this one!)
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* <endoflist>
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*
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* Copyright (c) 2004 Cisco Systems, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <crypto/hash.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/crc32c.h>
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static struct crypto_shash *tfm;
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u32 crc32c(u32 crc, const void *address, unsigned int length)
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{
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SHASH_DESC_ON_STACK(shash, tfm);
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u32 ret, *ctx = (u32 *)shash_desc_ctx(shash);
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int err;
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shash->tfm = tfm;
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*ctx = crc;
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err = crypto_shash_update(shash, address, length);
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BUG_ON(err);
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ret = *ctx;
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barrier_data(ctx);
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return ret;
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}
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EXPORT_SYMBOL(crc32c);
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static int __init libcrc32c_mod_init(void)
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{
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tfm = crypto_alloc_shash("crc32c", 0, 0);
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return PTR_ERR_OR_ZERO(tfm);
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}
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static void __exit libcrc32c_mod_fini(void)
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{
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crypto_free_shash(tfm);
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}
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const char *crc32c_impl(void)
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{
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return crypto_shash_driver_name(tfm);
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}
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EXPORT_SYMBOL(crc32c_impl);
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module_init(libcrc32c_mod_init);
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module_exit(libcrc32c_mod_fini);
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MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
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MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
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MODULE_LICENSE("GPL");
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MODULE_SOFTDEP("pre: crc32c");
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