include/linux/bitmap.h: make bitmap_fill() and bitmap_zero() consistent (334cfa48) · Commits · 戴 / test

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 <andriy.shevchenko@linux.intel.com> Suggested-by:

Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Yury Norov <ynorov@caviumnetworks.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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,

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