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Re: [Xen-devel] [PATCH v2 17/32] arm: define __smp_xxx

On Sat, Jan 02, 2016 at 11:24:38AM +0000, Russell King - ARM Linux wrote:
> On Thu, Dec 31, 2015 at 09:07:59PM +0200, Michael S. Tsirkin wrote:
> > This defines __smp_xxx barriers for arm,
> > for use by virtualization.
> > 
> > smp_xxx barriers are removed as they are
> > defined correctly by asm-generic/barriers.h
> > 
> > This reduces the amount of arch-specific boiler-plate code.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> > Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
> In combination with patch 14, this looks like it should result in no
> change to the resulting code.
> Acked-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
> My only concern is that it gives people an additional handle onto a
> "new" set of barriers - just because they're prefixed with __*
> unfortunately doesn't stop anyone from using it (been there with
> other arch stuff before.)
> I wonder whether we should consider making the smp memory barriers
> inline functions, so these __smp_xxx() variants can be undef'd
> afterwards, thereby preventing drivers getting their hands on these
> new macros?

That'd be tricky to do cleanly since asm-generic depends on
ifndef to add generic variants where needed.

But it would be possible to add a checkpatch test for this.

> -- 
> RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
> according to speedtest.net.

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