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

Eric Biggers
2024-10-25T19:15:46Z

From: Eric Biggers <ebiggers@google.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@google.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