RFR(s): 8152182: Possible overflow in initialzation of _rescan_task_size and _marking_task_size

[sangheon]

Hi all,

After some discussion with Jesper, I updated below:
1. Removed a flag value recommendation part. Maybe we need more tests on 
various machines and this way is mostly exception comparing to other 
flags' handling. So removing it.
2. Changed comments 'would' -> 'could'.

Updated webrev:
http://cr.openjdk.java.net/~sangheki/8152182/webrev.01_to_00
http://cr.openjdk.java.net/~sangheki/8152182/webrev.01_to_00

Thanks,
Sangheon


On 04/05/2016 10:24 AM, sangheon wrote:
> Hi all,
>
> Please review this change for CMSRescanMultiple and 
> CMSConcMarkMultiple flags.
>
> Both flags are set by "CardTableModRefBS::card_size_in_words * 
> BitsPerWord * flag" which potentially would make an overflow with 
> their maximum value without setting range. And these flags also would 
> make an arithmetic overflow when calculating with the size and the 
> start address of reserved area. In addition, CMSRescanMultiple needs 
> an alignment check.
>
> CR: https://bugs.openjdk.java.net/browse/JDK-8152182
> Webrev: http://cr.openjdk.java.net/~sangheki/8152182/webrev.00
> Testing: JPRT, runtime/commandline JTREG for all platforms
>
> Thanks,
> Sangheon