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lib: util_macros_kunit: add kunit test for util_macros.h
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A bug was found in the find_closest() (find_closest_descending() is also
affected after some testing), where for certain values with small
progressions of 1, 2 & 3, the rounding (done by averaging 2 values) causes
an incorrect index to be returned.

The bug is described in more detail in the commit which fixes the bug. 
This commit adds a kunit test to validate that the fix works correctly.

This kunit test adds some of the arrays (from the driver-sphere) that seem
to produce issues with the 'find_closest()' macro.  Specifically the one
from ad7606 driver (with which the bug was found) and from the ina2xx
drivers, which shows the quirk with 'find_closest()' with elements in a
array that have an interval of 3.

For the find_closest_descending() tests, the same arrays are used as for
the find_closest(), but in reverse; the idea is that
'find_closest_descending()' should return the sames indices as
'find_closest()' but in reverse.

For testing both macros, there are 4 special arrays created, one for
testing find_closest{_descending}() for arrays of progressions 1, 2, 3 and
4.  The idea is to show that (for progressions of 1, 2 & 3) the fix works
as expected.  When removing the fix, the issues should start to show up.

Then an extra array of negative and positive values is added.  There are
currently no such arrays within drivers, but one could expect that these
macros behave correctly even for such arrays.

To run this kunit:
  ./tools/testing/kunit/kunit.py run "*util_macros*"

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexandru Ardelean <[email protected]>
Cc: Bartosz Golaszewski <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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@commodo @akpm00
commodo authored and akpm00 committed Nov 12, 2024
1 parent bc73b41 commit 1113141
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17 changes: 17 additions & 0 deletions lib/Kconfig.debug
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Original file line number Diff line number Diff line change
Expand Up @@ -2630,6 +2630,23 @@ config CHECKSUM_KUNIT

If unsure, say N.

config UTIL_MACROS_KUNIT
tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Enable this option to test the util_macros.h function at boot.

KUnit tests run during boot and output the results to the debug log
in TAP format (http://testanything.org/). Only useful for kernel devs
running the KUnit test harness, and not intended for inclusion into a
production build.

For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.

If unsure, say N.

config HASH_KUNIT_TEST
tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
depends on KUNIT
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1 change: 1 addition & 0 deletions lib/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -372,6 +372,7 @@ obj-$(CONFIG_PLDMFW) += pldmfw/
CFLAGS_bitfield_kunit.o := $(DISABLE_STRUCTLEAK_PLUGIN)
obj-$(CONFIG_BITFIELD_KUNIT) += bitfield_kunit.o
obj-$(CONFIG_CHECKSUM_KUNIT) += checksum_kunit.o
obj-$(CONFIG_UTIL_MACROS_KUNIT) += util_macros_kunit.o
obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
obj-$(CONFIG_HASHTABLE_KUNIT_TEST) += hashtable_test.o
obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
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240 changes: 240 additions & 0 deletions lib/util_macros_kunit.c
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@@ -0,0 +1,240 @@
// SPDX-License-Identifier: GPL-2.0+
/*
* Test cases for bitfield helpers.
*/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <kunit/test.h>
#include <linux/util_macros.h>

#define FIND_CLOSEST_RANGE_CHECK(from, to, array, exp_idx) \
{ \
int i; \
for (i = from; i <= to; i++) { \
int found = find_closest(i, array, ARRAY_SIZE(array)); \
KUNIT_ASSERT_EQ(ctx, exp_idx, found); \
} \
}

static void test_find_closest(struct kunit *ctx)
{
/* This will test a few arrays that are found in drivers */
static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };
static const unsigned int ad7616_oversampling_avail[] = {
1, 2, 4, 8, 16, 32, 64, 128,
};
static u32 wd_timeout_table[] = { 2, 4, 6, 8, 16, 32, 48, 64 };
static int array_prog1a[] = { 1, 2, 3, 4, 5 };
static u32 array_prog1b[] = { 2, 3, 4, 5, 6 };
static int array_prog1mix[] = { -2, -1, 0, 1, 2 };
static int array_prog2a[] = { 1, 3, 5, 7 };
static u32 array_prog2b[] = { 2, 4, 6, 8 };
static int array_prog3a[] = { 1, 4, 7, 10 };
static u32 array_prog3b[] = { 2, 5, 8, 11 };
static int array_prog4a[] = { 1, 5, 9, 13 };
static u32 array_prog4b[] = { 2, 6, 10, 14 };

FIND_CLOSEST_RANGE_CHECK(-3, 2, ina226_avg_tab, 0);
FIND_CLOSEST_RANGE_CHECK(3, 10, ina226_avg_tab, 1);
FIND_CLOSEST_RANGE_CHECK(11, 40, ina226_avg_tab, 2);
FIND_CLOSEST_RANGE_CHECK(41, 96, ina226_avg_tab, 3);
FIND_CLOSEST_RANGE_CHECK(97, 192, ina226_avg_tab, 4);
FIND_CLOSEST_RANGE_CHECK(193, 384, ina226_avg_tab, 5);
FIND_CLOSEST_RANGE_CHECK(385, 768, ina226_avg_tab, 6);
FIND_CLOSEST_RANGE_CHECK(769, 2048, ina226_avg_tab, 7);

/* The array that found the bug that caused this kunit to exist */
FIND_CLOSEST_RANGE_CHECK(-3, 1, ad7616_oversampling_avail, 0);
FIND_CLOSEST_RANGE_CHECK(2, 3, ad7616_oversampling_avail, 1);
FIND_CLOSEST_RANGE_CHECK(4, 6, ad7616_oversampling_avail, 2);
FIND_CLOSEST_RANGE_CHECK(7, 12, ad7616_oversampling_avail, 3);
FIND_CLOSEST_RANGE_CHECK(13, 24, ad7616_oversampling_avail, 4);
FIND_CLOSEST_RANGE_CHECK(25, 48, ad7616_oversampling_avail, 5);
FIND_CLOSEST_RANGE_CHECK(49, 96, ad7616_oversampling_avail, 6);
FIND_CLOSEST_RANGE_CHECK(97, 256, ad7616_oversampling_avail, 7);

FIND_CLOSEST_RANGE_CHECK(-3, 3, wd_timeout_table, 0);
FIND_CLOSEST_RANGE_CHECK(4, 5, wd_timeout_table, 1);
FIND_CLOSEST_RANGE_CHECK(6, 7, wd_timeout_table, 2);
FIND_CLOSEST_RANGE_CHECK(8, 12, wd_timeout_table, 3);
FIND_CLOSEST_RANGE_CHECK(13, 24, wd_timeout_table, 4);
FIND_CLOSEST_RANGE_CHECK(25, 40, wd_timeout_table, 5);
FIND_CLOSEST_RANGE_CHECK(41, 56, wd_timeout_table, 6);
FIND_CLOSEST_RANGE_CHECK(57, 128, wd_timeout_table, 7);

/* One could argue that find_closest() should not be used for monotonic
* arrays (like 1,2,3,4,5), but even so, it should work as long as the
* array is sorted ascending. */
FIND_CLOSEST_RANGE_CHECK(-3, 1, array_prog1a, 0);
FIND_CLOSEST_RANGE_CHECK(2, 2, array_prog1a, 1);
FIND_CLOSEST_RANGE_CHECK(3, 3, array_prog1a, 2);
FIND_CLOSEST_RANGE_CHECK(4, 4, array_prog1a, 3);
FIND_CLOSEST_RANGE_CHECK(5, 8, array_prog1a, 4);

FIND_CLOSEST_RANGE_CHECK(-3, 2, array_prog1b, 0);
FIND_CLOSEST_RANGE_CHECK(3, 3, array_prog1b, 1);
FIND_CLOSEST_RANGE_CHECK(4, 4, array_prog1b, 2);
FIND_CLOSEST_RANGE_CHECK(5, 5, array_prog1b, 3);
FIND_CLOSEST_RANGE_CHECK(6, 8, array_prog1b, 4);

FIND_CLOSEST_RANGE_CHECK(-4, -2, array_prog1mix, 0);
FIND_CLOSEST_RANGE_CHECK(-1, -1, array_prog1mix, 1);
FIND_CLOSEST_RANGE_CHECK(0, 0, array_prog1mix, 2);
FIND_CLOSEST_RANGE_CHECK(1, 1, array_prog1mix, 3);
FIND_CLOSEST_RANGE_CHECK(2, 5, array_prog1mix, 4);

FIND_CLOSEST_RANGE_CHECK(-3, 2, array_prog2a, 0);
FIND_CLOSEST_RANGE_CHECK(3, 4, array_prog2a, 1);
FIND_CLOSEST_RANGE_CHECK(5, 6, array_prog2a, 2);
FIND_CLOSEST_RANGE_CHECK(7, 10, array_prog2a, 3);

FIND_CLOSEST_RANGE_CHECK(-3, 3, array_prog2b, 0);
FIND_CLOSEST_RANGE_CHECK(4, 5, array_prog2b, 1);
FIND_CLOSEST_RANGE_CHECK(6, 7, array_prog2b, 2);
FIND_CLOSEST_RANGE_CHECK(8, 10, array_prog2b, 3);

FIND_CLOSEST_RANGE_CHECK(-3, 2, array_prog3a, 0);
FIND_CLOSEST_RANGE_CHECK(3, 5, array_prog3a, 1);
FIND_CLOSEST_RANGE_CHECK(6, 8, array_prog3a, 2);
FIND_CLOSEST_RANGE_CHECK(9, 20, array_prog3a, 3);

FIND_CLOSEST_RANGE_CHECK(-3, 3, array_prog3b, 0);
FIND_CLOSEST_RANGE_CHECK(4, 6, array_prog3b, 1);
FIND_CLOSEST_RANGE_CHECK(7, 9, array_prog3b, 2);
FIND_CLOSEST_RANGE_CHECK(10, 20, array_prog3b, 3);

FIND_CLOSEST_RANGE_CHECK(-3, 3, array_prog4a, 0);
FIND_CLOSEST_RANGE_CHECK(4, 7, array_prog4a, 1);
FIND_CLOSEST_RANGE_CHECK(8, 11, array_prog4a, 2);
FIND_CLOSEST_RANGE_CHECK(12, 20, array_prog4a, 3);

FIND_CLOSEST_RANGE_CHECK(-3, 4, array_prog4b, 0);
FIND_CLOSEST_RANGE_CHECK(5, 8, array_prog4b, 1);
FIND_CLOSEST_RANGE_CHECK(9, 12, array_prog4b, 2);
FIND_CLOSEST_RANGE_CHECK(13, 20, array_prog4b, 3);
}

#define FIND_CLOSEST_DESC_RANGE_CHECK(from, to, array, exp_idx) \
{ \
int i; \
for (i = from; i <= to; i++) { \
int found = find_closest_descending(i, array, \
ARRAY_SIZE(array)); \
KUNIT_ASSERT_EQ(ctx, exp_idx, found); \
} \
}

static void test_find_closest_descending(struct kunit *ctx)
{
/* Same arrays as 'test_find_closest' but reversed */
static const int ina226_avg_tab[] = { 1024, 512, 256, 128, 64, 16, 4, 1 };
static const unsigned int ad7616_oversampling_avail[] = {
128, 64, 32, 16, 8, 4, 2, 1
};
static u32 wd_timeout_table[] = { 64, 48, 32, 16, 8, 6, 4, 2 };
static int array_prog1a[] = { 5, 4, 3, 2, 1 };
static u32 array_prog1b[] = { 6, 5, 4, 3, 2 };
static int array_prog1mix[] = { 2, 1, 0, -1, -2 };
static int array_prog2a[] = { 7, 5, 3, 1 };
static u32 array_prog2b[] = { 8, 6, 4, 2 };
static int array_prog3a[] = { 10, 7, 4, 1 };
static u32 array_prog3b[] = { 11, 8, 5, 2 };
static int array_prog4a[] = { 13, 9, 5, 1 };
static u32 array_prog4b[] = { 14, 10, 6, 2 };

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 2, ina226_avg_tab, 7);
FIND_CLOSEST_DESC_RANGE_CHECK(3, 10, ina226_avg_tab, 6);
FIND_CLOSEST_DESC_RANGE_CHECK(11, 40, ina226_avg_tab, 5);
FIND_CLOSEST_DESC_RANGE_CHECK(41, 96, ina226_avg_tab, 4);
FIND_CLOSEST_DESC_RANGE_CHECK(97, 192, ina226_avg_tab, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(193, 384, ina226_avg_tab, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(385, 768, ina226_avg_tab, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(769, 2048, ina226_avg_tab, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 1, ad7616_oversampling_avail, 7);
FIND_CLOSEST_DESC_RANGE_CHECK(2, 3, ad7616_oversampling_avail, 6);
FIND_CLOSEST_DESC_RANGE_CHECK(4, 6, ad7616_oversampling_avail, 5);
FIND_CLOSEST_DESC_RANGE_CHECK(7, 12, ad7616_oversampling_avail, 4);
FIND_CLOSEST_DESC_RANGE_CHECK(13, 24, ad7616_oversampling_avail, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(25, 48, ad7616_oversampling_avail, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(49, 96, ad7616_oversampling_avail, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(97, 256, ad7616_oversampling_avail, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 3, wd_timeout_table, 7);
FIND_CLOSEST_DESC_RANGE_CHECK(4, 5, wd_timeout_table, 6);
FIND_CLOSEST_DESC_RANGE_CHECK(6, 7, wd_timeout_table, 5);
FIND_CLOSEST_DESC_RANGE_CHECK(8, 12, wd_timeout_table, 4);
FIND_CLOSEST_DESC_RANGE_CHECK(13, 24, wd_timeout_table, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(25, 40, wd_timeout_table, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(41, 56, wd_timeout_table, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(57, 128, wd_timeout_table, 0);

/* One could argue that find_closest_descending() should not be used
* for monotonic arrays (like 5,4,3,2,1), but even so, it should still
* it should work as long as the array is sorted descending. */
FIND_CLOSEST_DESC_RANGE_CHECK(-3, 1, array_prog1a, 4);
FIND_CLOSEST_DESC_RANGE_CHECK(2, 2, array_prog1a, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(3, 3, array_prog1a, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(4, 4, array_prog1a, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(5, 8, array_prog1a, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 2, array_prog1b, 4);
FIND_CLOSEST_DESC_RANGE_CHECK(3, 3, array_prog1b, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(4, 4, array_prog1b, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(5, 5, array_prog1b, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(6, 8, array_prog1b, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-4, -2, array_prog1mix, 4);
FIND_CLOSEST_DESC_RANGE_CHECK(-1, -1, array_prog1mix, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(0, 0, array_prog1mix, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(1, 1, array_prog1mix, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(2, 5, array_prog1mix, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 2, array_prog2a, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(3, 4, array_prog2a, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(5, 6, array_prog2a, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(7, 10, array_prog2a, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 3, array_prog2b, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(4, 5, array_prog2b, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(6, 7, array_prog2b, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(8, 10, array_prog2b, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 2, array_prog3a, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(3, 5, array_prog3a, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(6, 8, array_prog3a, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(9, 20, array_prog3a, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 3, array_prog3b, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(4, 6, array_prog3b, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(7, 9, array_prog3b, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(10, 20, array_prog3b, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 3, array_prog4a, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(4, 7, array_prog4a, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(8, 11, array_prog4a, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(12, 20, array_prog4a, 0);

FIND_CLOSEST_DESC_RANGE_CHECK(-3, 4, array_prog4b, 3);
FIND_CLOSEST_DESC_RANGE_CHECK(5, 8, array_prog4b, 2);
FIND_CLOSEST_DESC_RANGE_CHECK(9, 12, array_prog4b, 1);
FIND_CLOSEST_DESC_RANGE_CHECK(13, 20, array_prog4b, 0);
}

static struct kunit_case __refdata util_macros_test_cases[] = {
KUNIT_CASE(test_find_closest),
KUNIT_CASE(test_find_closest_descending),
{}
};

static struct kunit_suite util_macros_test_suite = {
.name = "util_macros.h",
.test_cases = util_macros_test_cases,
};

kunit_test_suites(&util_macros_test_suite);

MODULE_AUTHOR("Alexandru Ardelean <[email protected]>");
MODULE_DESCRIPTION("Test cases for util_macros.h helpers");
MODULE_LICENSE("GPL");

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