[PATCH v4 15/19] lib/crc32: make crc32c() go directly to lib

[Eric Biggers]

From: Eric Biggers <ebiggers at 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 at kernel.org>
Signed-off-by: Eric Biggers <ebiggers at 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 8858030bebae..d0c2dc0dac32 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -308,18 +308,14 @@ 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 a8155c972f02..6573163d24e4 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -165,11 +165,10 @@ 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 at cisco.com>");
-MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
-MODULE_LICENSE("GPL");
-MODULE_SOFTDEP("pre: crc32c");
-- 
2.47.1