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bitmap: add test_zero_nbits()

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In most real-life cases, 0-length bitmap provided by user is a sign of
an error. The API doesn't provide any guarantees on returned value, and
the bitmap pointers are not dereferenced.

Signed-off-by: Yury Norov <ynorov@nvidia.com>
This commit is contained in:
Yury Norov 2026-03-18 20:43:48 -04:00
parent 2a4d3706d8
commit 95d324fb1b
2 changed files with 59 additions and 0 deletions
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2
lib/bitmap.c
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@ -69,6 +69,7 @@ bool __bitmap_or_equal(const unsigned long *bitmap1,
tmp = (bitmap1[k] | bitmap2[k]) ^ bitmap3[k];
return (tmp & BITMAP_LAST_WORD_MASK(bits)) == 0;
}
EXPORT_SYMBOL(__bitmap_or_equal);
void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
{
@ -360,6 +361,7 @@ unsigned int __bitmap_weighted_or(unsigned long *dst, const unsigned long *bitma
{
return BITMAP_WEIGHT(({dst[idx] = bitmap1[idx] | bitmap2[idx]; dst[idx]; }), bits);
}
EXPORT_SYMBOL(__bitmap_weighted_or);
void __bitmap_set(unsigned long *map, unsigned int start, int len)
{

57
lib/test_bitmap.c
View File

@ -1467,6 +1467,62 @@ static void __init test_bitmap_write_perf(void)
pr_info("%s:\t\t%llu\n", __func__, time);
}
/*
* nbits == 0 is most commonly not a valid case. Bitmap users should revisit
* the caller logic. Bitmap API doesn't provide any guarantees on returned
* value. The pointers are not dereferenced. The return value is intentionally
* ignored.
*/
static void __init test_zero_nbits(void)
{
static volatile __always_used unsigned long ret __initdata;
bitmap_clear(NULL, 0, 0);
bitmap_complement(NULL, NULL, 0);
bitmap_copy(NULL, NULL, 0);
bitmap_copy_clear_tail(NULL, NULL, 0);
bitmap_fill(NULL, 0);
bitmap_from_arr32(NULL, NULL, 0);
bitmap_from_arr64(NULL, NULL, 0);
bitmap_or(NULL, NULL, NULL, 0);
bitmap_set(NULL, 0, 0);
bitmap_shift_left(NULL, NULL, 0, 0);
bitmap_shift_right(NULL, NULL, 0, 0);
bitmap_to_arr32(NULL, NULL, 0);
bitmap_to_arr64(NULL, NULL, 0);
bitmap_write(NULL, 0, 0, 0);
bitmap_xor(NULL, NULL, NULL, 0);
bitmap_zero(NULL, 0);
ret = bitmap_and(NULL, NULL, NULL, 0);
ret = bitmap_empty(NULL, 0);
ret = bitmap_equal(NULL, NULL, 0);
ret = bitmap_full(NULL, 0);
ret = bitmap_or_equal(NULL, NULL, NULL, 0);
ret = bitmap_read(NULL, 0, 0);
ret = bitmap_subset(NULL, NULL, 0);
ret = bitmap_weight(NULL, 0);
ret = bitmap_weight_and(NULL, NULL, 0);
ret = bitmap_weight_andnot(NULL, NULL, 0);
ret = bitmap_weight_from(NULL, 0, 0);
ret = bitmap_weighted_or(NULL, NULL, NULL, 0);
ret = find_first_and_and_bit(NULL, NULL, NULL, 0);
ret = find_first_and_bit(NULL, NULL, 0);
ret = find_first_andnot_bit(NULL, NULL, 0);
ret = find_first_bit(NULL, 0);
ret = find_first_zero_bit(NULL, 0);
ret = find_last_bit(NULL, 0);
ret = find_next_and_bit(NULL, NULL, 0, 0);
ret = find_next_andnot_bit(NULL, NULL, 0, 0);
ret = find_next_bit(NULL, 0, 0);
ret = find_next_clump8(NULL, NULL, 0, 0);
ret = find_next_zero_bit(NULL, 0, 0);
ret = find_nth_and_bit(NULL, NULL, 0, 0);
ret = find_nth_bit(NULL, 0, 0);
ret = find_random_bit(NULL, 0);
}
#undef TEST_BIT_LEN
static void __init selftest(void)
@ -1490,6 +1546,7 @@ static void __init selftest(void)
test_bitmap_read_perf();
test_bitmap_weight();
test_bitmap_write_perf();
test_zero_nbits();
test_find_nth_bit();
test_for_each_set_bit();