On Mon, Apr 12, 2021 at 12:07 PM Daniel Latypov dlatypov@google.com wrote:
Add basic test coverage for files that don't require any config options:
- part of math.h (what seem to be the most commonly used macros)
- gcd.c
- lcm.c
- int_sqrt.c
- reciprocal_div.c
(Ignored int_pow.c since it's a simple textbook algorithm.)
These tests aren't particularly interesting, but they
- provide short and simple examples of parameterized tests
- provide a place to add tests for any new files in this dir
- are written so adding new test cases to cover edge cases should be easy
- looking at code coverage, we hit all the branches in the .c files
Bumping this thread to see what the status is.
I think it's useful to have tests spread across the kernel so there's "nearby" tests one can reference and/or copy-paste from. Now there's the lib/math/rational-test.c, there's less need here.
But I think having tests for simpler functions is still nice to have.
E.g. there's a performance trade-off documented in gcd.c If you'd want to run that test case to see if it still holds, you'd be able to run gcd() in a loop fairly easily with:
$ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/math lib-math.gcd_test
(KUnit doesn't yet have support for timing tests or running tests multiple times, so you'd have to tweak the test code for that).
Random fact: I'd noticed that after running some 1000s of internal integration tests , the gcd() function didn't actually get fully covered. Specifically, they never got to line 34, the for loop 23 unsigned long gcd(unsigned long a, unsigned long b) 24 { 25 unsigned long r = a | b; 26 27 if (!a || !b) 28 return r; 29 30 b >>= __ffs(b); 31 if (b == 1) 32 return r & -r; 33 34 for (;;) { Checking again now, a few months later, I see they now do hit that loop. But I guess until then, we'd only been calling gcd() with b=2^n.
Signed-off-by: Daniel Latypov dlatypov@google.com
Changes since v4:
- add in test cases for some math.h macros (abs, round_up/round_down, div_round_down/closest)
- use parameterized testing less to keep things terser
Changes since v3:
- fix `checkpatch.pl --strict` warnings
- add test cases for gcd(0,0) and lcm(0,0)
- minor: don't test both gcd(a,b) and gcd(b,a) when a == b
Changes since v2: mv math_test.c => math_kunit.c
Changes since v1:
- Rebase and rewrite to use the new parameterized testing support.
- misc: fix overflow in literal and inline int_sqrt format string.
- related: commit 1f0e943df68a ("Documentation: kunit: provide guidance
for testing many inputs") was merged explaining the patterns shown here.
- there's an in-flight patch to update it for parameterized testing.
v1: https://lore.kernel.org/lkml/20201019224556.3536790-1-dlatypov@google.com/
lib/math/Kconfig | 5 + lib/math/Makefile | 2 + lib/math/math_kunit.c | 264 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 271 insertions(+) create mode 100644 lib/math/math_kunit.c
diff --git a/lib/math/Kconfig b/lib/math/Kconfig index f19bc9734fa7..6ba8680439c1 100644 --- a/lib/math/Kconfig +++ b/lib/math/Kconfig @@ -15,3 +15,8 @@ config PRIME_NUMBERS
config RATIONAL bool
+config MATH_KUNIT_TEST
tristate "KUnit test for lib/math" if !KUNIT_ALL_TESTSdefault KUNIT_ALL_TESTSdepends on KUNITdiff --git a/lib/math/Makefile b/lib/math/Makefile index be6909e943bd..30abb7a8d564 100644 --- a/lib/math/Makefile +++ b/lib/math/Makefile @@ -4,3 +4,5 @@ obj-y += div64.o gcd.o lcm.o int_pow.o int_sqrt.o reciprocal_div.o obj-$(CONFIG_CORDIC) += cordic.o obj-$(CONFIG_PRIME_NUMBERS) += prime_numbers.o obj-$(CONFIG_RATIONAL) += rational.o
+obj-$(CONFIG_MATH_KUNIT_TEST) += math_kunit.o diff --git a/lib/math/math_kunit.c b/lib/math/math_kunit.c new file mode 100644 index 000000000000..80a087a32884 --- /dev/null +++ b/lib/math/math_kunit.c @@ -0,0 +1,264 @@ +// SPDX-License-Identifier: GPL-2.0 +/*
- Simple KUnit suite for math helper funcs that are always enabled.
- Copyright (C) 2020, Google LLC.
- Author: Daniel Latypov dlatypov@google.com
- */
+#include <kunit/test.h> +#include <linux/gcd.h> +#include <linux/kernel.h> +#include <linux/lcm.h> +#include <linux/reciprocal_div.h>
+static void abs_test(struct kunit *test) +{
KUNIT_EXPECT_EQ(test, abs('\0'), '\0');KUNIT_EXPECT_EQ(test, abs('a'), 'a');KUNIT_EXPECT_EQ(test, abs(-'a'), 'a');/* The expression in the macro is actually promoted to an int. */KUNIT_EXPECT_EQ(test, abs((short)0), 0);KUNIT_EXPECT_EQ(test, abs((short)42), 42);KUNIT_EXPECT_EQ(test, abs((short)-42), 42);KUNIT_EXPECT_EQ(test, abs(0), 0);KUNIT_EXPECT_EQ(test, abs(42), 42);KUNIT_EXPECT_EQ(test, abs(-42), 42);KUNIT_EXPECT_EQ(test, abs(0L), 0L);KUNIT_EXPECT_EQ(test, abs(42L), 42L);KUNIT_EXPECT_EQ(test, abs(-42L), 42L);KUNIT_EXPECT_EQ(test, abs(0LL), 0LL);KUNIT_EXPECT_EQ(test, abs(42LL), 42LL);KUNIT_EXPECT_EQ(test, abs(-42LL), 42LL);/* Unsigned types get casted to signed. */KUNIT_EXPECT_EQ(test, abs(0ULL), 0LL);KUNIT_EXPECT_EQ(test, abs(42ULL), 42LL);+}
+static void int_sqrt_test(struct kunit *test) +{
KUNIT_EXPECT_EQ(test, int_sqrt(0UL), 0UL);KUNIT_EXPECT_EQ(test, int_sqrt(1UL), 1UL);KUNIT_EXPECT_EQ(test, int_sqrt(4UL), 2UL);KUNIT_EXPECT_EQ(test, int_sqrt(5UL), 2UL);KUNIT_EXPECT_EQ(test, int_sqrt(8UL), 2UL);KUNIT_EXPECT_EQ(test, int_sqrt(1UL << 30), 1UL << 15);+}
+static void round_up_test(struct kunit *test) +{
KUNIT_EXPECT_EQ(test, round_up(0, 1), 0);KUNIT_EXPECT_EQ(test, round_up(1, 2), 2);KUNIT_EXPECT_EQ(test, round_up(3, 2), 4);KUNIT_EXPECT_EQ(test, round_up((1 << 30) - 1, 2), 1 << 30);KUNIT_EXPECT_EQ(test, round_up((1 << 30) - 1, 1 << 29), 1 << 30);+}
+static void round_down_test(struct kunit *test) +{
KUNIT_EXPECT_EQ(test, round_down(0, 1), 0);KUNIT_EXPECT_EQ(test, round_down(1, 2), 0);KUNIT_EXPECT_EQ(test, round_down(3, 2), 2);KUNIT_EXPECT_EQ(test, round_down((1 << 30) - 1, 2), (1 << 30) - 2);KUNIT_EXPECT_EQ(test, round_down((1 << 30) - 1, 1 << 29), 1 << 29);+}
+static void div_round_up_test(struct kunit *test) +{
KUNIT_EXPECT_EQ(test, DIV_ROUND_UP(0, 1), 0);KUNIT_EXPECT_EQ(test, DIV_ROUND_UP(20, 10), 2);KUNIT_EXPECT_EQ(test, DIV_ROUND_UP(21, 10), 3);KUNIT_EXPECT_EQ(test, DIV_ROUND_UP(21, 20), 2);KUNIT_EXPECT_EQ(test, DIV_ROUND_UP(21, 99), 1);+}
+static void div_round_closest_test(struct kunit *test) +{
KUNIT_EXPECT_EQ(test, DIV_ROUND_CLOSEST(0, 1), 0);KUNIT_EXPECT_EQ(test, DIV_ROUND_CLOSEST(20, 10), 2);KUNIT_EXPECT_EQ(test, DIV_ROUND_CLOSEST(21, 10), 2);KUNIT_EXPECT_EQ(test, DIV_ROUND_CLOSEST(25, 10), 3);+}
+/* Generic test case for unsigned long inputs. */ +struct test_case {
unsigned long a, b;unsigned long result;+};
+static struct test_case gcd_cases[] = {
{.a = 0, .b = 0,.result = 0,},{.a = 0, .b = 1,.result = 1,},{.a = 2, .b = 2,.result = 2,},{.a = 2, .b = 4,.result = 2,},{.a = 3, .b = 5,.result = 1,},{.a = 3 * 9, .b = 3 * 5,.result = 3,},{.a = 3 * 5 * 7, .b = 3 * 5 * 11,.result = 15,},{.a = 1 << 21,.b = (1 << 21) - 1,.result = 1,},+};
+KUNIT_ARRAY_PARAM(gcd, gcd_cases, NULL);
+static void gcd_test(struct kunit *test) +{
const char *message_fmt = "gcd(%lu, %lu)";const struct test_case *test_param = test->param_value;KUNIT_EXPECT_EQ_MSG(test, test_param->result,gcd(test_param->a, test_param->b),message_fmt, test_param->a,test_param->b);if (test_param->a == test_param->b)return;/* gcd(a,b) == gcd(b,a) */KUNIT_EXPECT_EQ_MSG(test, test_param->result,gcd(test_param->b, test_param->a),message_fmt, test_param->b,test_param->a);+}
+static struct test_case lcm_cases[] = {
{.a = 0, .b = 0,.result = 0,},{.a = 0, .b = 1,.result = 0,},{.a = 1, .b = 2,.result = 2,},{.a = 2, .b = 2,.result = 2,},{.a = 3 * 5, .b = 3 * 7,.result = 3 * 5 * 7,},+};
+KUNIT_ARRAY_PARAM(lcm, lcm_cases, NULL);
+static void lcm_test(struct kunit *test) +{
const char *message_fmt = "lcm(%lu, %lu)";const struct test_case *test_param = test->param_value;KUNIT_EXPECT_EQ_MSG(test, test_param->result,lcm(test_param->a, test_param->b),message_fmt, test_param->a,test_param->b);if (test_param->a == test_param->b)return;/* lcm(a,b) == lcm(b,a) */KUNIT_EXPECT_EQ_MSG(test, test_param->result,lcm(test_param->b, test_param->a),message_fmt, test_param->b,test_param->a);+}
+struct u32_test_case {
u32 a, b;u32 result;+};
+static struct u32_test_case reciprocal_div_cases[] = {
{.a = 0, .b = 1,.result = 0,},{.a = 42, .b = 20,.result = 2,},{.a = 42, .b = 9999,.result = 0,},{.a = (1 << 16), .b = (1 << 14),.result = 1 << 2,},+};
+KUNIT_ARRAY_PARAM(reciprocal_div, reciprocal_div_cases, NULL);
+static void reciprocal_div_test(struct kunit *test) +{
const struct u32_test_case *test_param = test->param_value;struct reciprocal_value rv = reciprocal_value(test_param->b);KUNIT_EXPECT_EQ_MSG(test, test_param->result,reciprocal_divide(test_param->a, rv),"reciprocal_divide(%u, %u)",test_param->a, test_param->b);+}
+static void reciprocal_scale_test(struct kunit *test) +{
KUNIT_EXPECT_EQ(test, reciprocal_scale(0u, 100), 0u);KUNIT_EXPECT_EQ(test, reciprocal_scale(1u, 100), 0u);KUNIT_EXPECT_EQ(test, reciprocal_scale(1u << 4, 1 << 28), 1u);KUNIT_EXPECT_EQ(test, reciprocal_scale(1u << 16, 1 << 28), 1u << 12);KUNIT_EXPECT_EQ(test, reciprocal_scale(~0u, 1 << 28), (1u << 28) - 1);+}
+static struct kunit_case math_test_cases[] = {
KUNIT_CASE(abs_test),KUNIT_CASE(int_sqrt_test),KUNIT_CASE(round_up_test),KUNIT_CASE(round_down_test),KUNIT_CASE(div_round_up_test),KUNIT_CASE(div_round_closest_test),KUNIT_CASE_PARAM(gcd_test, gcd_gen_params),KUNIT_CASE_PARAM(lcm_test, lcm_gen_params),KUNIT_CASE_PARAM(reciprocal_div_test, reciprocal_div_gen_params),KUNIT_CASE(reciprocal_scale_test),{}+};
+static struct kunit_suite math_test_suite = {
.name = "lib-math",.test_cases = math_test_cases,+};
+kunit_test_suites(&math_test_suite);
+MODULE_LICENSE("GPL v2");
base-commit: 4fa56ad0d12e24df768c98bffe9039f915d1bc02
2.31.1.295.g9ea45b61b8-goog