From: Andy Shevchenko Date: Tue, 6 Feb 2018 23:38:20 +0000 (-0800) Subject: include/linux/bitmap.h: make bitmap_fill() and bitmap_zero() consistent X-Git-Tag: v4.19~1628^2~74 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=334cfa48d38f5416c125a71a57f72d6cf634d797;p=platform%2Fkernel%2Flinux-rpi.git include/linux/bitmap.h: make bitmap_fill() and bitmap_zero() consistent 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 are handled differently and in such cases bitmap_set() has to be used. Link: http://lkml.kernel.org/r/20180109172430.87452-4-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Suggested-by: Rasmus Villemoes Cc: Randy Dunlap Cc: Yury Norov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index e43533e..d9bf699 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. */ /** @@ -202,12 +207,12 @@ 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,