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

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 28/07/2010 15:57, "Patrick Colp" <pjcolp@xxxxxxxxx> wrote:

>>> ++        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.

Avoiding the if is better. Everyone knows free(0) is legal, so it's
idiomatic to unconditionally call free().

 -- Keir



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