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authorAndy Shevchenko <andriy.shevchenko@linux.intel.com>2018-02-06 15:38:20 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 18:32:44 -0800
commit334cfa48d38f5416c125a71a57f72d6cf634d797 (patch)
treefee2a87aa695e98d29fe0043b58525101a860c2f /include
parentfe81814c3e091adde489e9d7ac1179340845e396 (diff)
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 <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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/bitmap.h15
1 files changed, 10 insertions, 5 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index e43533ec7660..d9bf699e0e7a 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,