Adds test suite for integer based square root function.

The test suite is designed to verify the correctness of the int_sqrt()
math library function.

Signed-off-by: Luis Felipe Hernandez <luis.hernandez093@gmail.com>
---
Changes in v2
  - Add new line at the end of int_sqrt_kunit.c
  - Add explicit header includes for MODULE_* macros, strscpy, and ULONG_MAX

Changes in v3
  - Remove unnecessary new line after Kconfig entry for INT_SQRT_KUNIT_TEST
  - Correct int_sqrt instances with int_sqrt() in commit message and kconfig
entry desc
  - Fix limits.h header include path

Changes in v4
  - Fix Kconfig entry: remove redundant word test

Changes in v5
  - Address review feedback by Nicolas Pitre <npitre@baylibre.com>
    - Make edge case portable by not relying on arch dependent macro
    - Add more edge cases
Changes in v6
  - Address review feedback by Alan Stern <stern@rowland.harvard.edu>
    - ref: https://lore.kernel.org/all/ad95d09e-ddbe-4d43-bf22-00c2008823d8@rowland.harvard.edu/
    - Correct recipient list
    - Spelling and typography fixes
      - sqaure -> square
      - remove extra white space
    - Add edge cases to validates boundaries around perfect square
---
 lib/Kconfig.debug               | 15 ++++++++
 lib/math/Makefile               |  1 +
 lib/math/tests/Makefile         |  1 +
 lib/math/tests/int_sqrt_kunit.c | 66 +++++++++++++++++++++++++++++++++
 4 files changed, 83 insertions(+)
 create mode 100644 lib/math/tests/int_sqrt_kunit.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f3d723705879..147d9fef42e7 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -3161,6 +3161,21 @@ config INT_POW_TEST
 
 	  If unsure, say N
 
+config INT_SQRT_KUNIT_TEST
+	tristate "Integer square root test" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This option enables the KUnit test suite for the int_sqrt() function,
+	  which performs square root calculation. The test suite checks
+	  various scenarios, including edge cases, to ensure correctness.
+
+	  Enabling this option will include tests that check various scenarios
+	  and edge cases to ensure the accuracy and reliability of the square root
+	  function.
+
+	  If unsure, say N
+
 endif # RUNTIME_TESTING_MENU
 
 config ARCH_USE_MEMTEST
diff --git a/lib/math/Makefile b/lib/math/Makefile
index 3ef11305f8d2..25bcb968b369 100644
--- a/lib/math/Makefile
+++ b/lib/math/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_INT_POW_TEST)  += tests/int_pow_kunit.o
 obj-$(CONFIG_TEST_DIV64)	+= test_div64.o
 obj-$(CONFIG_TEST_MULDIV64)	+= test_mul_u64_u64_div_u64.o
 obj-$(CONFIG_RATIONAL_KUNIT_TEST) += rational-test.o
+obj-y  += tests/
diff --git a/lib/math/tests/Makefile b/lib/math/tests/Makefile
index 6a169123320a..e1a79f093b2d 100644
--- a/lib/math/tests/Makefile
+++ b/lib/math/tests/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
 obj-$(CONFIG_INT_POW_TEST) += int_pow_kunit.o
+obj-$(CONFIG_INT_SQRT_KUNIT_TEST) += int_sqrt_kunit.o
diff --git a/lib/math/tests/int_sqrt_kunit.c b/lib/math/tests/int_sqrt_kunit.c
new file mode 100644
index 000000000000..1798e1312eb7
--- /dev/null
+++ b/lib/math/tests/int_sqrt_kunit.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <kunit/test.h>
+#include <linux/limits.h>
+#include <linux/math.h>
+#include <linux/module.h>
+#include <linux/string.h>
+
+struct test_case_params {
+	unsigned long x;
+	unsigned long expected_result;
+	const char *name;
+};
+
+static const struct test_case_params params[] = {
+	{ 0, 0, "edge case: square root of 0" },
+	{ 1, 1, "perfect square: square root of 1" },
+	{ 2, 1, "non-perfect square: square root of 2" },
+	{ 3, 1, "non-perfect square: square root of 3" },
+	{ 4, 2, "perfect square: square root of 4" },
+	{ 5, 2, "non-perfect square: square root of 5" },
+	{ 6, 2, "non-perfect square: square root of 6" },
+	{ 7, 2, "non-perfect square: square root of 7" },
+	{ 8, 2, "non-perfect square: square root of 8" },
+	{ 9, 3, "perfect square: square root of 9" },
+	{ 15, 3, "non-perfect square: square root of 15 (N-1 from 16)" },
+	{ 16, 4, "perfect square: square root of 16" },
+	{ 17, 4, "non-perfect square: square root of 17 (N+1 from 16)" },
+	{ 80, 8, "non-perfect square: square root of 80 (N-1 from 81)" },
+	{ 81, 9, "perfect square: square root of 81" },
+	{ 82, 9, "non-perfect square: square root of 82 (N+1 from 81)" },
+	{ 255, 15, "non-perfect square: square root of 255 (N-1 from 256)" },
+	{ 256, 16, "perfect square: square root of 256" },
+	{ 257, 16, "non-perfect square: square root of 257 (N+1 from 256)" },
+	{ 2147483648, 46340, "large input: square root of 2147483648" },
+	{ 4294967295, 65535, "edge case: ULONG_MAX for 32-bit" },
+};
+
+static void get_desc(const struct test_case_params *tc, char *desc)
+{
+	strscpy(desc, tc->name, KUNIT_PARAM_DESC_SIZE);
+}
+
+KUNIT_ARRAY_PARAM(int_sqrt, params, get_desc);
+
+static void int_sqrt_test(struct kunit *test)
+{
+	const struct test_case_params *tc = (const struct test_case_params *)test->param_value;
+
+	KUNIT_EXPECT_EQ(test, tc->expected_result, int_sqrt(tc->x));
+}
+
+static struct kunit_case math_int_sqrt_test_cases[] = {
+	KUNIT_CASE_PARAM(int_sqrt_test, int_sqrt_gen_params),
+	{}
+};
+
+static struct kunit_suite int_sqrt_test_suite = {
+	.name = "math-int_sqrt",
+	.test_cases = math_int_sqrt_test_cases,
+};
+
+kunit_test_suites(&int_sqrt_test_suite);
+
+MODULE_DESCRIPTION("math.int_sqrt KUnit test suite");
+MODULE_LICENSE("GPL");
-- 
2.47.1

On Wed, 11 Dec 2024 21:12:58 -0500 Luis Felipe Hernandez <luis.hernandez093@gmail.com> wrote:

> Adds test suite for integer based square root function.
> 
> The test suite is designed to verify the correctness of the int_sqrt()
> math library function.
> 

my x86_64 allmodconfig build says

  AR      built-in.a
  AR      vmlinux.a
error: the following would cause module name conflict:
  lib/math/tests/int_pow_kunit.ko
  lib/math/tests/int_pow_kunit.ko
make[1]: *** [/usr/src/25/Makefile:1925: modules_check] Error 1

On Wed, Dec 11, 2024 at 11:18:16PM -0800, Andrew Morton wrote: 
> my x86_64 allmodconfig build says
> 
>   AR      built-in.a
>   AR      vmlinux.a
> error: the following would cause module name conflict:
>   lib/math/tests/int_pow_kunit.ko
>   lib/math/tests/int_pow_kunit.ko
> make[1]: *** [/usr/src/25/Makefile:1925: modules_check] Error 1
> 
Hi Andrew,

Thank you for your time and pointing out the issue. The duplicate entry
for int_pow_kunit in lib/math/Makefile and lib/math/tests/Makefile stems
from my attempt to align this patch with another[1] I had authored in a
series by David Gow that moves all lib/math/ KUnit tests to lib/math/tests/.

Since that series hasn’t landed yet, I’ll update this patch by reverting to the
current mainline approach, keeping the object file assignment in lib/math/Makefile.
This avoids assuming the approach in the David's patch series and prevents conflicts.
Once both patches are merged, I'll create a follow-up patch to align everything properly.

I apologize for the confusion and back-and-forth on this patch.
In reviewing your earlier feedback from v3 of this patch[2], I now realize
what you were referring to regarding the conflict. At the time, I failed to
fully understand the issue.

I appreciate your patience, and I’ll do my best to resolve this in a way that
minimizes further disruption.

[1] https://lore.kernel.org/all/20241202075545.3648096-2-davidgow@google.com/
[2] https://lore.kernel.org/all/20241031173941.3487ccbfd7421d81d9b0cb97@linux-foundation.org/

Best,

Felipe