[PATCH net-next 07/10] lib/crc32: remove unused support for CRC32C combination

Eric Biggers
2025-05-11T00:41:36Z

From: Eric Biggers <ebiggers@google.com>

crc32c_combine() and crc32c_shift() are no longer used (except by the
KUnit test that tests them), and their current implementation is very
slow. Remove them.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
include/linux/crc32.h | 23 -----------------------
lib/crc32.c | 6 ------
lib/tests/crc_kunit.c | 6 ------
3 files changed, 35 deletions(-)

diff --git a/include/linux/crc32.h b/include/linux/crc32.h
index 69c2e8bb3782..7f7d0be8a0ac 100644
--- a/include/linux/crc32.h
+++ b/include/linux/crc32.h
@@ -74,33 +74,10 @@ u32 crc32_le_shift(u32 crc, size_t len);
static inline u32 crc32_le_combine(u32 crc1, u32 crc2, size_t len2)
{
return crc32_le_shift(crc1, len2) ^ crc2;
}

-u32 crc32c_shift(u32 crc, size_t len);
-
-/**
- * crc32c_combine - Combine two crc32c check values into one. For two sequences
- * of bytes, seq1 and seq2 with lengths len1 and len2, crc32c()
- * check values were calculated for each, crc1 and crc2.
- *
- * @crc1: crc32c of the first block
- * @crc2: crc32c of the second block
- * @len2: length of the second block
- *
- * Return: The crc32c() check value of seq1 and seq2 concatenated, requiring
- * only crc1, crc2, and len2. Note: If seq_full denotes the concatenated
- * memory area of seq1 with seq2, and crc_full the crc32c() value of
- * seq_full, then crc_full == crc32c_combine(crc1, crc2, len2) when
- * crc_full was seeded with the same initializer as crc1, and crc2 seed
- * was 0. See also crc_combine_test().
- */
-static inline u32 crc32c_combine(u32 crc1, u32 crc2, size_t len2)
-{
- return crc32c_shift(crc1, len2) ^ crc2;
-}
-
#define crc32(seed, data, length) crc32_le(seed, (unsigned char const *)(data), length)

/*
* Helpers for hash table generation of ethernet nics:
*
diff --git a/lib/crc32.c b/lib/crc32.c
index fddd424ff224..ade48bbb0083 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -117,16 +117,10 @@ u32 crc32_le_shift(u32 crc, size_t len)
{
return crc32_generic_shift(crc, len, CRC32_POLY_LE);
}
EXPORT_SYMBOL(crc32_le_shift);

-u32 crc32c_shift(u32 crc, size_t len)
-{
- return crc32_generic_shift(crc, len, CRC32C_POLY_LE);
-}
-EXPORT_SYMBOL(crc32c_shift);
-
u32 crc32_be_base(u32 crc, const u8 *p, size_t len)
{
while (len--)
crc = (crc << 8) ^ crc32table_be[(crc >> 24) ^ *p++];
return crc;
diff --git a/lib/tests/crc_kunit.c b/lib/tests/crc_kunit.c
index 585c48b65cef..064c2d581557 100644
--- a/lib/tests/crc_kunit.c
+++ b/lib/tests/crc_kunit.c
@@ -389,21 +389,15 @@ static void crc32_be_benchmark(struct kunit *test)
static u64 crc32c_wrapper(u64 crc, const u8 *p, size_t len)
{
return crc32c(crc, p, len);
}

-static u64 crc32c_combine_wrapper(u64 crc1, u64 crc2, size_t len2)
-{
- return crc32c_combine(crc1, crc2, len2);
-}
-
static const struct crc_variant crc_variant_crc32c = {
.bits = 32,
.le = true,
.poly = 0x82f63b78,
.func = crc32c_wrapper,
- .combine_func = crc32c_combine_wrapper,
};

static void crc32c_test(struct kunit *test)
{
crc_test(test, &crc_variant_crc32c);
--
2.49.0