[PATCH v2 14/18] lib/crc32: make crc32c() go directly to lib

Eric Biggers
2024-10-25T19:15:52Z

From: Eric Biggers <ebiggers@google.com>

Now that the lower level __crc32c_le() library function is optimized for
each architecture, make crc32c() just call that instead of taking an
inefficient and error-prone detour through the shash API.

Note: a future cleanup should make crc32c_le() be the actual library
function instead of __crc32c_le(). That will require updating callers
of __crc32c_le() to use crc32c_le() instead, and updating callers of
crc32c_le() that expect a 'const void *' arg to expect 'const u8 *'
instead. Similarly, a future cleanup should remove LIBCRC32C by making
everyone who is selecting it just select CRC32 directly instead.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
include/linux/crc32c.h | 7 ++--
lib/Kconfig | 10 ++----
lib/Makefile | 1 -
lib/libcrc32c.c | 74 ------------------------------------------
4 files changed, 8 insertions(+), 84 deletions(-)
delete mode 100644 lib/libcrc32c.c

diff --git a/include/linux/crc32c.h b/include/linux/crc32c.h
index 357ae4611a45..47eb78003c26 100644
--- a/include/linux/crc32c.h
+++ b/include/linux/crc32c.h
@@ -1,12 +1,15 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_CRC32C_H
#define _LINUX_CRC32C_H

-#include <linux/types.h>
+#include <linux/crc32.h>

-extern u32 crc32c(u32 crc, const void *address, unsigned int length);
+static inline u32 crc32c(u32 crc, const void *address, unsigned int length)
+{
+ return __crc32c_le(crc, address, length);
+}

/* This macro exists for backwards-compatibility. */
#define crc32c_le crc32c

#endif /* _LINUX_CRC32C_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index 07afcf214f35..b894ee64ff95 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -296,18 +296,14 @@ config CRC7
the kernel tree does. Such modules that use library CRC7
functions require M here.

config LIBCRC32C
tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
- select CRYPTO
- select CRYPTO_CRC32C
+ select CRC32
help
- This option is provided for the case where no in-kernel-tree
- modules require CRC32c functions, but a module built outside the
- kernel tree does. Such modules that use library CRC32c functions
- require M here. See Castagnoli93.
- Module will be libcrc32c.
+ This option just selects CRC32 and is provided for compatibility
+ purposes until the users are updated to select CRC32 directly.

config CRC8
tristate "CRC8 function"
help
This option provides CRC8 function. Drivers may select this
diff --git a/lib/Makefile b/lib/Makefile
index 773adf88af41..15646679aee2 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -161,11 +161,10 @@ obj-$(CONFIG_CRC_ITU_T) += crc-itu-t.o
obj-$(CONFIG_CRC32) += crc32.o
obj-$(CONFIG_CRC64) += crc64.o
obj-$(CONFIG_CRC32_SELFTEST) += crc32test.o
obj-$(CONFIG_CRC4) += crc4.o
obj-$(CONFIG_CRC7) += crc7.o
-obj-$(CONFIG_LIBCRC32C) += libcrc32c.o
obj-$(CONFIG_CRC8) += crc8.o
obj-$(CONFIG_CRC64_ROCKSOFT) += crc64-rocksoft.o
obj-$(CONFIG_XXHASH) += xxhash.o
obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o

diff --git a/lib/libcrc32c.c b/lib/libcrc32c.c
deleted file mode 100644
index 649e687413a0..000000000000
--- a/lib/libcrc32c.c
+++ /dev/null
@@ -1,74 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * CRC32C
- *@Article{castagnoli-crc,
- * author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
- * title = {{Optimization of Cyclic Redundancy-Check Codes with 24
- * and 32 Parity Bits}},
- * journal = IEEE Transactions on Communication,
- * year = {1993},
- * volume = {41},
- * number = {6},
- * pages = {},
- * month = {June},
- *}
- * Used by the iSCSI driver, possibly others, and derived from
- * the iscsi-crc.c module of the linux-iscsi driver at
- * http://linux-iscsi.sourceforge.net.
- *
- * Following the example of lib/crc32, this function is intended to be
- * flexible and useful for all users. Modules that currently have their
- * own crc32c, but hopefully may be able to use this one are:
- * net/sctp (please add all your doco to here if you change to
- * use this one!)
- * <endoflist>
- *
- * Copyright (c) 2004 Cisco Systems, Inc.
- */
-
-#include <crypto/hash.h>
-#include <linux/err.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/crc32c.h>
-
-static struct crypto_shash *tfm;
-
-u32 crc32c(u32 crc, const void *address, unsigned int length)
-{
- SHASH_DESC_ON_STACK(shash, tfm);
- u32 ret, *ctx = (u32 *)shash_desc_ctx(shash);
- int err;
-
- shash->tfm = tfm;
- *ctx = crc;
-
- err = crypto_shash_update(shash, address, length);
- BUG_ON(err);
-
- ret = *ctx;
- barrier_data(ctx);
- return ret;
-}
-
-EXPORT_SYMBOL(crc32c);
-
-static int __init libcrc32c_mod_init(void)
-{
- tfm = crypto_alloc_shash("crc32c", 0, 0);
- return PTR_ERR_OR_ZERO(tfm);
-}
-
-static void __exit libcrc32c_mod_fini(void)
-{
- crypto_free_shash(tfm);
-}
-
-module_init(libcrc32c_mod_init);
-module_exit(libcrc32c_mod_fini);
-
-MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
-MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
-MODULE_LICENSE("GPL");
-MODULE_SOFTDEP("pre: crc32c");
--
2.47.0