Re: [PATCH 07/12] KVM: X86/MMU: Remove the useless struct mmu_page_path

From: Lai Jiangshan
Date: Thu Jul 21 2022 - 05:43:37 EST


On Wed, Jul 20, 2022 at 4:15 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>
> Nit, s/useless/now-unused, or "no longer used". I associate "useless" in shortlogs
> as "this <xyz> is pointless and always has been pointless", whereas "now-unused"
> is likely to be interpreted as "remove <xyz> as it's no longer used after recent
> changes".
>
> Alternatively, can this patch be squashed with the patch that removes
> mmu_pages_clear_parents()? Yeah, it'll be a (much?) larger patch, but leaving
> dead code behind is arguably worse.

Defined by the C-language and the machine, struct mmu_page_path is used
in for_each_sp() and the data is set and updated every iteration.

It is not really dead code.

Defined by the sematic that we want, gathering unsync pages,
we don't need struct mmu_page_path, since the struct is not used
by "someone reading it".

>
> On Sun, Jun 05, 2022, Lai Jiangshan wrote:
> > From: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
> >
> > struct mmu_page_path is set and updated but never used since
> > mmu_pages_clear_parents() is removed.
> >
> > Remove it.
> >
> > Signed-off-by: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
> > ---