On 10/25/2012 10:46 AM, Eric Blake wrote:
>>> +
>>> + /* Ensure tail bits are clear. */
>>> + if (tail)
>>> + bitmap->map[bitmap->map_len - 1] &=
>>> + -1UL >> (VIR_BITMAP_BITS_PER_UNIT - tail);
>> Probably not necessary, as the bitmap is initialized to zero.
>
> Absolutely necessary, or 'make check' fails. But debatable whether to
> put it here, or to shift it to virBitmapSetAll() (as THAT appears to be
> the only culprit function that ever sets tail-bits to 1).
>
>>
>> Works for me.
>
> Thanks for the review. I think I'll move the tail clearing to
> virBitmapSetAll, as that is likely to be the less-frequently called
> function, and maintaining the invariant that tail bits are always clear
> seems nicer than assuming they are undefined and having to explicitly
> clear tail bits prior to a count operation.
>
I've now pushed the series with this squashed in. Thanks for your
initial work, and for testing my changes.
diff --git i/src/util/bitmap.c w/src/util/bitmap.c
index 9a9152a..2dd3403 100644
--- i/src/util/bitmap.c
+++ w/src/util/bitmap.c
@@ -528,8 +528,15 @@ size_t virBitmapSize(virBitmapPtr bitmap)
*/
void virBitmapSetAll(virBitmapPtr bitmap)
{
+ int tail = bitmap->max_bit % VIR_BITMAP_BITS_PER_UNIT;
+
memset(bitmap->map, 0xff,
bitmap->map_len * (VIR_BITMAP_BITS_PER_UNIT / CHAR_BIT));
+
+ /* Ensure tail bits are clear. */
+ if (tail)
+ bitmap->map[bitmap->map_len - 1] &=
+ -1UL >> (VIR_BITMAP_BITS_PER_UNIT - tail);
}
/**
@@ -621,12 +628,6 @@ virBitmapCountBits(virBitmapPtr bitmap)
{
size_t i;
size_t ret = 0;
- int tail = bitmap->max_bit % VIR_BITMAP_BITS_PER_UNIT;
-
- /* Ensure tail bits are clear. */
- if (tail)
- bitmap->map[bitmap->map_len - 1] &=
- -1UL >> (VIR_BITMAP_BITS_PER_UNIT - tail);
for (i = 0; i < bitmap->map_len; i++)
ret += count_one_bits_l(bitmap->map[i]);
--
Eric Blake eblake@xxxxxxxxxx +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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