Re: [RESEND2 PATCH 1/3] memremap: add MEMREMAP_WC flag

[Brian Starkey]

Hi Andrew,

Would you pick these up if I rebase onto linux-next?

How strongly do you feel about the input argument modification vs.
staying in-line with the rest of the function?

Thanks,

Brian

On Tue, Feb 09, 2016 at 10:23:00AM +0000, Brian Starkey wrote:
> Hi Andrew,
>
> Thanks for taking a look,
>
> On Mon, Feb 08, 2016 at 12:03:17PM -0800, Andrew Morton wrote:
> > On Mon,  8 Feb 2016 17:30:50 +0000 Brian Starkey <brian.starkey@xxxxxxx> wrote:
> > The patch generally looks OK to me.  It generates rejects against
> > linux-next because of some janitorial changes in memremap.c.
>
> Ah yeah, so it does - sorry. I was hoping this could make it into 4.5,
> but I can rebase onto linux-next if that's better. Annoyingly it only
> conflicts because of a couple of quotation marks.
>
> > > @@ -101,6 +107,11 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
> > > 		addr = ioremap_wt(offset, size);
> > > 	}
> > >
> > > +	if (!addr && (flags & MEMREMAP_WC)) {
> > > +		flags &= ~MEMREMAP_WC;
> > > +		addr = ioremap_wc(offset, size);
> > > +	}
> > > +
> > > 	return addr;
> > > }
> >
> > The modifications of `flags' is unneeded (and the compiler will remove
> > it).  And generally the modification of incoming args is a bit nasty
> > IMO - I find it's better to treat them as const - part of the calling
> > environment which can be relied upon to be unaltered as the code
> > evolves.
>
> To be honest I was just mirroring the rest of the function. I guess
> the idea was filtering the different mapping types in case one of the
> 'mappers' can handle multiple flags or something. I'll remove it if
> you like, I just thought that extending the functionality in-keeping
> with the current semantics was a better evolution - let me know.
>
> Thanks,
> Brian