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Commit 334cfa48 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Linus Torvalds
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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: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Suggested-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fe81814c

include/linux/bitmap.h

+10 −5
Original line number Diff line number Diff line
@@ -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);

	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,