On Mon, Aug 12, 2019 at 06:18:43PM +0200, Paolo Bonzini wrote:
>On 18/07/19 03:04, Wei Yang wrote:
>> The value left in nr is the number of bits for the last word, which
>> could be calculate the last word mask directly.
>>
>> Remove the unnecessary size.
>
>Hi,
>
>the value left in nr is _not_ the number of bits for the last word if
>the start and the end are in the same word. For example, if start %
>BITS_PER_LONG was 3 and nr == 1, you'd have:
>
>- before the patch BITMAP_LAST_WORD_MASK(4)
>
>- after the patch BITMAP_LAST_WORD_MASK(1)
>
You are right. I missed this case.
Thanks for pointing out.
>Paolo
>
>> Signed-off-by: Wei Yang <richardw.y...@linux.intel.com>
>>
>> ---
>> v2: refine bitmap_set_atomic too, suggested from Peter
>> ---
>> util/bitmap.c | 9 +++------
>> 1 file changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/util/bitmap.c b/util/bitmap.c
>> index 1753ff7f5b..5b15249796 100644
>> --- a/util/bitmap.c
>> +++ b/util/bitmap.c
>> @@ -160,7 +160,6 @@ int slow_bitmap_andnot(unsigned long *dst, const
>> unsigned long *bitmap1,
>> void bitmap_set(unsigned long *map, long start, long nr)
>> {
>> unsigned long *p = map + BIT_WORD(start);
>> - const long size = start + nr;
>> int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
>> unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
>>
>> @@ -174,7 +173,7 @@ void bitmap_set(unsigned long *map, long start, long nr)
>> p++;
>> }
>> if (nr) {
>> - mask_to_set &= BITMAP_LAST_WORD_MASK(size);
>> + mask_to_set &= BITMAP_LAST_WORD_MASK(nr);
>> *p |= mask_to_set;
>> }
>> }
>> @@ -182,7 +181,6 @@ void bitmap_set(unsigned long *map, long start, long nr)
>> void bitmap_set_atomic(unsigned long *map, long start, long nr)
>> {
>> unsigned long *p = map + BIT_WORD(start);
>> - const long size = start + nr;
>> int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
>> unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
>>
>> @@ -208,7 +206,7 @@ void bitmap_set_atomic(unsigned long *map, long start,
>> long nr)
>>
>> /* Last word */
>> if (nr) {
>> - mask_to_set &= BITMAP_LAST_WORD_MASK(size);
>> + mask_to_set &= BITMAP_LAST_WORD_MASK(nr);
>> atomic_or(p, mask_to_set);
>> } else {
>> /* If we avoided the full barrier in atomic_or(), issue a
>> @@ -221,7 +219,6 @@ void bitmap_set_atomic(unsigned long *map, long start,
>> long nr)
>> void bitmap_clear(unsigned long *map, long start, long nr)
>> {
>> unsigned long *p = map + BIT_WORD(start);
>> - const long size = start + nr;
>> int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
>> unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
>>
>> @@ -235,7 +232,7 @@ void bitmap_clear(unsigned long *map, long start, long
>> nr)
>> p++;
>> }
>> if (nr) {
>> - mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
>> + mask_to_clear &= BITMAP_LAST_WORD_MASK(nr);
>> *p &= ~mask_to_clear;
>> }
>> }
>>
>
--
Wei Yang
Help you, Help me
