[PATCH 5/5] bitmap: Return size when no zero area is found
From: Yury Norov <hidden>
Date: 2026-07-09 02:03:49
Also in:
linux-arm-kernel, linux-crypto, linux-media, lkml
Subsystem:
bitmap api, library code, the rest · Maintainers:
Yury Norov, Andrew Morton, Linus Torvalds
Return the bitmap size, rather than size + 1, when bitmap_find_next_zero_area_off() cannot find a suitable area. This matches the conventional find_bit() failure sentinel and still lets callers detect failure with an out-of-range check. Document the public failure contract as a value greater than or equal to the bitmap size, without requiring callers to depend on the exact sentinel. Signed-off-by: Yury Norov <redacted> --- include/linux/bitmap.h | 3 +++ lib/bitmap.c | 10 ++++------ 2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 8854acf77869..33f175a30304 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h@@ -209,6 +209,9 @@ unsigned long bitmap_find_next_zero_area_off(unsigned long *map, * The @align_mask should be one less than a power of 2; the effect is that * the bit offset of all zero areas this function finds is multiples of that * power of 2. A @align_mask of 0 means no alignment is required. + * + * Return: The bit offset of the found area or a value >= @size + * if no area is found. */ static __always_inline unsigned long bitmap_find_next_zero_area(unsigned long *map,
diff --git a/lib/bitmap.c b/lib/bitmap.c
index b464d843f4eb..ed685127a107 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c@@ -424,6 +424,9 @@ EXPORT_SYMBOL(__bitmap_clear); * The @align_mask should be one less than a power of 2; the effect is that * the bit offset of all zero areas this function finds plus @align_offset * is multiple of that power of 2. + * + * Return: The bit offset of the found area or a value greater than or equal + * to @size if no area is found. */ unsigned long bitmap_find_next_zero_area_off(unsigned long *map, unsigned long size,
@@ -448,12 +451,7 @@ unsigned long bitmap_find_next_zero_area_off(unsigned long *map, start = i; } - /* - * Here, returning size + 1 is to maintain consistency - * with the old version, where the return value is always - * greater than size when no zero areas are found. - */ - return size + 1; + return size; } EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
--
2.53.0