Re: [Xen-devel] [PATCH 2 of 3] xenpaging: Fix-up xenpaging tool code

[Patrick Colp <pjcolp@xxxxxxxxx>]

On 28 July 2010 10:00, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:
> Patrick Colp writes ("[Xen-devel] [PATCH 2 of 3] xenpaging: Fix-up xenpaging 
> tool code"):
>>   err:
>> -    if ( paging->bitmap )
>> -        free(paging->bitmap);
>> -    if ( paging->platform_info )
>> -        free(paging->platform_info);
>>      if ( paging )
>> +    {
>> +        if ( paging->bitmap )
>> +            free(paging->bitmap);
>
> While you're doing this, why not replace
>
>>-+        if ( paging->bitmap )
>>-+            free(paging->bitmap);
> with
>
>>++        free(paging->bitmap);
>
> since free(0) is legal and a no-op ?

Could do, but free(0) isn't exactly a no-op. free() does a check to
see if the pointer passed was 0. So it doesn't really make much
difference if I do the check or let it do the check. I can easily
change the code to just do free(paging->bitmap) though, if that's the
preferred way to do it. Actually, I would argue my way is better since
in the case of a NULL pointer, the free function isn't called at all,
which saves a bunch of cycles.


Patrick

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