提交 334cfa48 编写于 作者: A Andy Shevchenko 提交者: Linus Torvalds

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.comSigned-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Suggested-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 fe81814c
......@@ -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,
......
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