Re: [PATCH v2] mm/swapfile.c: simplify the scan loop in scan_swap_map_slots()

Wei Yang
2020-04-25T00:30:16Z

On Fri, Apr 24, 2020 at 10:02:58AM +0800, Huang, Ying wrote:
>Wei Yang <richard.weiyang@gmail.com> writes:
>
[...]
>>>
>>>if "offset > si->highest_bit" is true and "offset < scan_base" is true,
>>>scan_base need to be returned.
>>>
>>
>> When this case would happen in the original code?
>
>In the original code, the loop can still stop.
>

Sorry, I don't get your point yet.

In original code, there are two separate loops

while (++offset <= si->highest_bit) {
}

while (offset < scan_base) {
}

And for your condition, (offset > highest_bit) && (offset < scan_base), which
terminates the first loop and fits the second loop well.

Not sure how this condition would stop the loop in original code?

>Best Regards,
>Huang, Ying
>
>>>Again, the new code doesn't make it easier to find this kind of issues.
>>>
>>>Best Regards,
>>>Huang, Ying

--
Wei Yang
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