Re: [PATCH] mm: Remove usages of ACCESS_ONCE

From: Jason Low
Date: Tue Mar 24 2015 - 12:58:42 EST


On Tue, 2015-03-24 at 15:42 +0100, Christian Borntraeger wrote:
> Am 23.03.2015 um 23:44 schrieb Jason Low:
> > Commit 38c5ce936a08 converted ACCESS_ONCE usage in gup_pmd_range() to
> > READ_ONCE, since ACCESS_ONCE doesn't work reliably on non-scalar types.
> >
> > This patch removes the rest of the usages of ACCESS_ONCE, and use
> > READ_ONCE for the read accesses. This also makes things cleaner,
> > instead of using separate/multiple sets of APIs.
> >
> > Signed-off-by: Jason Low <jason.low2@xxxxxx>
>
> Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>

Thanks.

> one remark or question:
>
> > - anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
> > + anon_mapping = (unsigned long)READ_ONCE(page->mapping);
>
> Were the white space changes intentional? IIRC checkpatch does prefer
> it your way and you have changed several places - so I assume yes.

Yeah, those changes were intentional.

I thought that this was more of the standard style to do casting, so I
made those changes as well.

> Either way, its probably fine to change that along.

Okay, I'll assume that this is fine for now unless something thinks this
shouldn't be part of the patch.

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