lib/tests/test_hash.c

Source file repositories/reference/linux-study-clean/lib/tests/test_hash.c

File Facts

System
Linux kernel
Corpus path
lib/tests/test_hash.c
Extension
.c
Size
6761 bytes
Lines
240
Domain
Kernel Services
Bucket
lib
Inferred role
Kernel Services: implementation source
Status
source implementation candidate

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

struct test_hash_params {
        /* Pointer to integer to be hashed. */
	unsigned long long *h64;
        /* Low 32-bits of integer to be hashed. */
	u32 h0;
        /* Arch-specific hash result. */
	u32 h1;
        /* Generic hash result. */
	u32 h2;
        /* ORed hashes of given size (in bits). */
	u32 (*hash_or)[33];
};

#ifdef HAVE_ARCH__HASH_32
static void
test_int__hash_32(struct kunit *test, struct test_hash_params *params)
{
	params->hash_or[1][0] |= params->h2 = __hash_32_generic(params->h0);
#if HAVE_ARCH__HASH_32 == 1
	KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,
			    "__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
			    params->h0, params->h1, params->h2);
#endif
}
#endif

#ifdef HAVE_ARCH_HASH_64
static void
test_int_hash_64(struct kunit *test, struct test_hash_params *params, u32 const *m, int *k)
{
	params->h2 = hash_64_generic(*params->h64, *k);
#if HAVE_ARCH_HASH_64 == 1
	KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,
			    "hash_64(%#llx, %d) = %#x != hash_64_generic() = %#x",
			    *params->h64, *k, params->h1, params->h2);
#else
	KUNIT_EXPECT_LE_MSG(test, params->h1, params->h2,
			    "hash_64_generic(%#llx, %d) = %#x > %#x",
			    *params->h64, *k, params->h1, *m);
#endif
}
#endif

/*
 * Test the various integer hash functions.  h64 (or its low-order bits)
 * is the integer to hash.  hash_or accumulates the OR of the hash values,
 * which are later checked to see that they cover all the requested bits.
 *
 * Because these functions (as opposed to the string hashes) are all
 * inline, the code being tested is actually in the module, and you can
 * recompile and re-test the module without rebooting.
 */
static void
test_int_hash(struct kunit *test, unsigned long long h64, u32 hash_or[2][33])
{
	int k;
	struct test_hash_params params = { &h64, (u32)h64, 0, 0, hash_or };

	/* Test __hash32 */
	hash_or[0][0] |= params.h1 = __hash_32(params.h0);
#ifdef HAVE_ARCH__HASH_32
	test_int__hash_32(test, &params);
#endif

	/* Test k = 1..32 bits */
	for (k = 1; k <= 32; k++) {
		u32 const m = ((u32)2 << (k-1)) - 1;	/* Low k bits set */

		/* Test hash_32 */
		hash_or[0][k] |= params.h1 = hash_32(params.h0, k);
		KUNIT_EXPECT_LE_MSG(test, params.h1, m,
				    "hash_32(%#x, %d) = %#x > %#x",
				    params.h0, k, params.h1, m);

		/* Test hash_64 */
		hash_or[1][k] |= params.h1 = hash_64(h64, k);
		KUNIT_EXPECT_LE_MSG(test, params.h1, m,
				    "hash_64(%#llx, %d) = %#x > %#x",
				    h64, k, params.h1, m);
#ifdef HAVE_ARCH_HASH_64
		test_int_hash_64(test, &params, &m, &k);
#endif
	}
}

#define SIZE 256	/* Run time is cubic in SIZE */

static void test_string_or(struct kunit *test)
{
	char buf[SIZE+1];

Annotation

Implementation Notes