linux-kernel - [PATCH v2 04/18] crypto: crc32 - don't unnecessarily register arch algorithms

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Message-ID: <20241025191454.72616-5-ebiggers@kernel.org>
Date: Fri, 25 Oct 2024 12:14:40 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: linux-arch@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-crypto@...r.kernel.org,
	linux-ext4@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-mips@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-s390@...r.kernel.org,
	linux-scsi@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	loongarch@...ts.linux.dev,
	sparclinux@...r.kernel.org,
	x86@...nel.org
Subject: [PATCH v2 04/18] crypto: crc32 - don't unnecessarily register arch algorithms

From: Eric Biggers <ebiggers@...gle.com>

Instead of registering the crc32-$arch and crc32c-$arch algorithms if
the arch-specific code was built, only register them when that code was
built *and* is not falling back to the base implementation at runtime.

This avoids confusing users like btrfs which checks the shash driver
name to determine whether it is crc32c-generic.

(It would also make sense to change btrfs to test the crc32_optimization
flags itself, so that it doesn't have to use the weird hack of parsing
the driver name.  This change still makes sense either way though.)

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 crypto/crc32_generic.c  | 8 ++++++--
 crypto/crc32c_generic.c | 8 ++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/crypto/crc32_generic.c b/crypto/crc32_generic.c
index cc064ea8240e..cecd01e4d6e6 100644
--- a/crypto/crc32_generic.c
+++ b/crypto/crc32_generic.c
@@ -155,19 +155,23 @@ static struct shash_alg algs[] = {{
 	.base.cra_ctxsize	= sizeof(u32),
 	.base.cra_module	= THIS_MODULE,
 	.base.cra_init		= crc32_cra_init,
 }};
 
+static int num_algs;
+
 static int __init crc32_mod_init(void)
 {
 	/* register the arch flavor only if it differs from the generic one */
-	return crypto_register_shashes(algs, 1 + IS_ENABLED(CONFIG_CRC32_ARCH));
+	num_algs = 1 + ((crc32_optimizations & CRC32_LE_OPTIMIZATION) != 0);
+
+	return crypto_register_shashes(algs, num_algs);
 }
 
 static void __exit crc32_mod_fini(void)
 {
-	crypto_unregister_shashes(algs, 1 + IS_ENABLED(CONFIG_CRC32_ARCH));
+	crypto_unregister_shashes(algs, num_algs);
 }
 
 subsys_initcall(crc32_mod_init);
 module_exit(crc32_mod_fini);
 
diff --git a/crypto/crc32c_generic.c b/crypto/crc32c_generic.c
index 04b03d825cf4..47d694da9d4a 100644
--- a/crypto/crc32c_generic.c
+++ b/crypto/crc32c_generic.c
@@ -195,19 +195,23 @@ static struct shash_alg algs[] = {{
 	.base.cra_ctxsize	= sizeof(struct chksum_ctx),
 	.base.cra_module	= THIS_MODULE,
 	.base.cra_init		= crc32c_cra_init,
 }};
 
+static int num_algs;
+
 static int __init crc32c_mod_init(void)
 {
 	/* register the arch flavor only if it differs from the generic one */
-	return crypto_register_shashes(algs, 1 + IS_ENABLED(CONFIG_CRC32_ARCH));
+	num_algs = 1 + ((crc32_optimizations & CRC32C_OPTIMIZATION) != 0);
+
+	return crypto_register_shashes(algs, num_algs);
 }
 
 static void __exit crc32c_mod_fini(void)
 {
-	crypto_unregister_shashes(algs, 1 + IS_ENABLED(CONFIG_CRC32_ARCH));
+	crypto_unregister_shashes(algs, num_algs);
 }
 
 subsys_initcall(crc32c_mod_init);
 module_exit(crc32c_mod_fini);
 
-- 
2.47.0