Behaviour of bitmap_fill() differs from bitmap_zero() in a way how bits behind bitmap are handed. bitmap_zero() clears entire bitmap by unsigned long boundary, while bitmap_fill() mimics bitmap_set().
Here we change bitmap_fill() behaviour to be consistent with bitmap_zero() and add a note to documentation. The change might reveal some bugs in the code where unused bits handled differently and in such cases bitmap_set() has to be used. Suggested-by: Rasmus Villemoes <[email protected]> Signed-off-by: Andy Shevchenko <[email protected]> --- include/linux/bitmap.h | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index a17b5121d4f5..49aea0b37994 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -67,6 +67,11 @@ * bitmap_from_arr32(dst, buf, nbits) Copy nbits from u32[] buf to dst * bitmap_to_arr32(buf, src, nbits) Copy nbits from buf to u32[] dst * + * Note, bitmap_zero() and bitmap_fill() operate over the region of + * unsigned longs, that is, bits behind bitmap till the unsigned long + * boundary will be zeroed or filled as well. Consider to use + * bitmap_clear() or bitmap_set() to make explicit zeroing or filling + * respectively. */ /** @@ -206,12 +211,12 @@ static inline void bitmap_zero(unsigned long *dst, unsigned int nbits) static inline void bitmap_fill(unsigned long *dst, unsigned int nbits) { - unsigned int nlongs = BITS_TO_LONGS(nbits); - if (!small_const_nbits(nbits)) { - unsigned int len = (nlongs - 1) * sizeof(unsigned long); - memset(dst, 0xff, len); + if (small_const_nbits(nbits)) + *dst = ~0UL; + else { + unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long); + memset(dst, 0xff, len); } - dst[nlongs - 1] = BITMAP_LAST_WORD_MASK(nbits); } static inline void bitmap_copy(unsigned long *dst, const unsigned long *src, -- 2.15.1
