>>> On Wed, Jun 4, 2008 at 5:09 PM, in message
<1212613754.19205.25.camel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Peter Zijlstra
<peterz@xxxxxxxxxxxxx> wrote:
> On Wed, 2008-06-04 at 15:04 -0400, Gregory Haskins wrote:
>> A rounding error was pointed out by Peter Zijlstra which would result
>> in the structure holding priorities to be off by one.
>>
>> Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
>> CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
>> ---
>>
>> kernel/sched_cpupri.h | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/kernel/sched_cpupri.h b/kernel/sched_cpupri.h
>> index 16d29b9..817c55c 100644
>> --- a/kernel/sched_cpupri.h
>> +++ b/kernel/sched_cpupri.h
>> @@ -4,7 +4,7 @@
>> #include <linux/sched.h>
>>
>> #define CPUPRI_NR_PRIORITIES 2+MAX_RT_PRIO
>> -#define CPUPRI_NR_PRI_WORDS CPUPRI_NR_PRIORITIES/BITS_PER_LONG
>> +#define CPUPRI_NR_PRI_WORDS (CPUPRI_NR_PRIORITIES +
> BITS_PER_LONG/2)/BITS_PER_LONG
>
> (33 + 16) / 32 = 49 / 32 = 1
>
> So its still wrong ;-)
>
> Please use DECLARE_BITMAP and or BITS_TO_LONGS to avoid these issues.
Indeed. Here is a new version:
(Thanks, Peter!)
------
sched: fix cpupri priocount
A rounding error was pointed out by Peter Zijlstra which would result
in the structure holding priorities to be off by one.
Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
diff --git a/kernel/sched_cpupri.h b/kernel/sched_cpupri.h
index 16d29b9..51e6553 100644
--- a/kernel/sched_cpupri.h
+++ b/kernel/sched_cpupri.h
@@ -4,7 +4,7 @@
#include <linux/sched.h>
#define CPUPRI_NR_PRIORITIES 2+MAX_RT_PRIO
-#define CPUPRI_NR_PRI_WORDS CPUPRI_NR_PRIORITIES/BITS_PER_LONG
+#define CPUPRI_NR_PRI_WORDS BITS_TO_LONGS(CPUPRI_NR_PRIORITIES)
#define CPUPRI_INVALID -1
#define CPUPRI_IDLE 0
--
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