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authorYury Norov2024-05-02 10:12:56 -0700
committerYury Norov2024-05-09 09:25:08 -0700
commit0b2811ba11b04353033237359c9d042eb0cdc1c1 (patch)
tree457edbccba4f262f89ac844914158f7705857ff4 /lib
parent77db1920a88103e8ef9ee58130df7c970aea3d17 (diff)
bitmap: relax find_nth_bit() limitation on return value
The function claims to return the bitmap size, if Nth bit doesn't exist. This rule is violated in inline case because the fns() that is used there doesn't know anything about size of the bitmap. So, relax this requirement to '>= size', and make the outline implementation a bit cheaper. All in-tree kernel users of find_nth_bit() are safe against that. Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Closes: https://lore.kernel.org/all/Zi50cAgR8nZvgLa3@yury-ThinkPad/T/#m6da806a0525e74dcc91f35e5f20766ed4e853e8a Signed-off-by: Yury Norov <yury.norov@gmail.com>
Diffstat (limited to 'lib')
-rw-r--r--lib/find_bit.c2
-rw-r--r--lib/test_bitmap.c4
2 files changed, 3 insertions, 3 deletions
diff --git a/lib/find_bit.c b/lib/find_bit.c
index 32f99e9a670e..0bddfc3ff248 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -87,7 +87,7 @@ out: \
if (sz % BITS_PER_LONG) \
tmp = (FETCH) & BITMAP_LAST_WORD_MASK(sz); \
found: \
- sz = min(idx * BITS_PER_LONG + fns(tmp, nr), sz); \
+ sz = idx * BITS_PER_LONG + fns(tmp, nr); \
out: \
sz; \
})
diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 6b2b33579f56..088838f829c9 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -244,7 +244,7 @@ static void __init test_find_nth_bit(void)
expect_eq_uint(60, find_nth_bit(bmap, 64 * 3, 5));
expect_eq_uint(80, find_nth_bit(bmap, 64 * 3, 6));
expect_eq_uint(123, find_nth_bit(bmap, 64 * 3, 7));
- expect_eq_uint(64 * 3, find_nth_bit(bmap, 64 * 3, 8));
+ expect_eq_uint(0, !!(find_nth_bit(bmap, 64 * 3, 8) < 64 * 3));
expect_eq_uint(10, find_nth_bit(bmap, 64 * 3 - 1, 0));
expect_eq_uint(20, find_nth_bit(bmap, 64 * 3 - 1, 1));
@@ -254,7 +254,7 @@ static void __init test_find_nth_bit(void)
expect_eq_uint(60, find_nth_bit(bmap, 64 * 3 - 1, 5));
expect_eq_uint(80, find_nth_bit(bmap, 64 * 3 - 1, 6));
expect_eq_uint(123, find_nth_bit(bmap, 64 * 3 - 1, 7));
- expect_eq_uint(64 * 3 - 1, find_nth_bit(bmap, 64 * 3 - 1, 8));
+ expect_eq_uint(0, !!(find_nth_bit(bmap, 64 * 3 - 1, 8) < 64 * 3 - 1));
for_each_set_bit(bit, exp1, EXP1_IN_BITS) {
b = find_nth_bit(exp1, EXP1_IN_BITS, cnt++);