Re: [PATCH 1/3] checkpatch.pl: add missing memory barriers

2016-01-04 Thread Russell King - ARM Linux 
On Mon, Jan 04, 2016 at 08:07:40AM -0800, Joe Perches wrote:
> On Mon, 2016-01-04 at 13:36 +0200, Michael S. Tsirkin wrote:
> > +   my $all_barriers = join('|', (@barriers, @smp_barriers));
> > +
> > +   if ($line =~ /\b($all_barriers)\(/) {
> 
> It would be better to use /\b$all_barriers\s*\(/
> as there's no reason for the capture and there
> could be a space between the function and the
> open parenthesis.

I think you mean

/\b(?:$all_barriers)\s*\(/

as 'all_barriers' will be:

mb|wmb|rmb|smp_mb|smp_wmb|smp_rmb

and putting that into your suggestion results in:

/\bmb|wmb|rmb|smp_mb|smp_wmb|smp_rmb\s*\(/

which is clearly wrong - the \b only applies to 'mb' and the \s*\( only
applies to smp_rmb.

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Re: [PATCH v2 08/32] arm: reuse asm-generic/barrier.h

2016-01-02 Thread Russell King - ARM Linux 
On Thu, Dec 31, 2015 at 09:06:46PM +0200, Michael S. Tsirkin wrote:
> On arm smp_store_mb, read_barrier_depends, smp_read_barrier_depends,
> smp_store_release, smp_load_acquire, smp_mb__before_atomic and
> smp_mb__after_atomic match the asm-generic variants exactly. Drop the
> local definitions and pull in asm-generic/barrier.h instead.
> 
> This is in preparation to refactoring this code area.
> 
> Signed-off-by: Michael S. Tsirkin 
> Acked-by: Arnd Bergmann 

Thanks, the asm-generic versions looks identical to me, so this should
result in no code generation difference.

Acked-by: Russell King 

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

2016-01-02 Thread Russell King - ARM Linux 
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 
> Acked-by: Arnd Bergmann 

In combination with patch 14, this looks like it should result in no
change to the resulting code.

Acked-by: Russell King 

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?

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