Linux Virtualization - Jan 2016 - [PATCH v2 1/3] checkpatch.pl: add missing memory barriers

On Sun, 2016-01-10 at 13:56 +0200, Michael S. Tsirkin
wrote:
> SMP-only barriers were missing in checkpatch.pl
> 
> Refactor code slightly to make adding more variants easier.
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -5116,7 +5116,25 @@ sub process {
> ?			}
> ?		}
> ?# check for memory barriers without a comment.
> -		if ($line =~
/\b(mb|rmb|wmb|read_barrier_depends|smp_mb|smp_rmb|smp_wmb|smp_read_barrier_depends)\(/)
{
> +
> +		my $barriers = qr{
> +			mb|
> +			rmb|
> +			wmb|
> +			read_barrier_depends
> +		}x;
> +		my $smp_barriers = qr{
> +			store_release|
> +			load_acquire|
> +			store_mb|
> +			($barriers)
> +		}x;
If I use a variable called $smp_barriers, I'd expect
it to actually be the smp_barriers, not to have to
prefix it with smp_ before using it.

		my $smp_barriers = qr{
			smp_store_release|
			smp_load_acquire|
			smp_store_mb|
			smp_read_barrier_depends
		}x;

or

		my $smp_barriers = qr{
			smp_(?:store_release|load_acquire|store_mb|read_barrier_depends)
		}x;

?
> +		my $all_barriers = qr{
> +			$barriers|
> +			smp_($smp_barriers)
> +		}x;
And this shouldn't have a capture group.

		my $all_barriers = qr{
			$barriers|
			$smp_barriers
		}x;		
> +
> +		if ($line =~ /\b($all_barriers)\s*\(/) {
This doesn't need the capture group either (?:all_barriers)
> ?			if (!ctx_has_comment($first_line, $linenr))
> {
> ?				WARN("MEMORY_BARRIER",
> ?				?????"memory barrier without
> comment\n" . $herecurr);

On Sun, 2016-01-10 at 07:07 -0800, Joe Perches wrote:
> On Sun, 2016-01-10 at 13:56 +0200, Michael S. Tsirkin wrote:
> > SMP-only barriers were missing in checkpatch.pl
> > 
> > Refactor code slightly to make adding more variants easier.
> []
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> If I use a variable called $smp_barriers, I'd expect
> it to actually be the smp_barriers, not to have to
> prefix it with smp_ before using it.
> 
> 		my $smp_barriers = qr{
> 			smp_store_release|
> 			smp_load_acquire|
> 			smp_store_mb|
> 			smp_read_barrier_depends
That's missing (?:barriers) too.

btw: shouldn't this also have
	smp_mb__(?:before|after)_atomic
?

On Sun, Jan 10, 2016 at 07:07:05AM -0800, Joe Perches
wrote:
> On Sun, 2016-01-10 at 13:56 +0200, Michael S. Tsirkin wrote:
> > SMP-only barriers were missing in checkpatch.pl
> > 
> > Refactor code slightly to make adding more variants easier.
> []
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
> > @@ -5116,7 +5116,25 @@ sub process {
> > ?			}
> > ?		}
> > ?# check for memory barriers without a comment.
> > -		if ($line =~
/\b(mb|rmb|wmb|read_barrier_depends|smp_mb|smp_rmb|smp_wmb|smp_read_barrier_depends)\(/)
{
> > +
> > +		my $barriers = qr{
> > +			mb|
> > +			rmb|
> > +			wmb|
> > +			read_barrier_depends
> > +		}x;
> > +		my $smp_barriers = qr{
> > +			store_release|
> > +			load_acquire|
> > +			store_mb|
> > +			($barriers)
> > +		}x;
> 
> If I use a variable called $smp_barriers, I'd expect
> it to actually be the smp_barriers, not to have to
> prefix it with smp_ before using it.
> 
> 		my $smp_barriers = qr{
> 			smp_store_release|
> 			smp_load_acquire|
> 			smp_store_mb|
> 			smp_read_barrier_depends
> 		}x;
> 
> or
> 
> 		my $smp_barriers = qr{
> 			smp_(?:store_release|load_acquire|store_mb|read_barrier_depends)
> 		}x;
> 
Yes but virt barriers (added in patch 3) are same things but prefixed
with virt_.  So we need the stems without smp_ prefix. If smp_barriers is
too confusing we'll just need to give them some other name.
How about:
my $smp_barrier_stems

?
> > +		my $all_barriers = qr{
> > +			$barriers|
> > +			smp_($smp_barriers)
> > +		}x;
> 
> And this shouldn't have a capture group.
> 
> 		my $all_barriers = qr{
> 			$barriers|
> 			$smp_barriers
> 		}x;		
> > +
> > +		if ($line =~ /\b($all_barriers)\s*\(/) {
> 
> This doesn't need the capture group either (?:all_barriers)
> 
> > ?			if (!ctx_has_comment($first_line, $linenr))
> > {
> > ?				WARN("MEMORY_BARRIER",
> > ?				?????"memory barrier without
> > comment\n" . $herecurr);

On Sun, Jan 10, 2016 at 07:17:31AM -0800, Joe Perches
wrote:
> On Sun, 2016-01-10 at 07:07 -0800, Joe Perches wrote:
> > On Sun, 2016-01-10 at 13:56 +0200, Michael S. Tsirkin wrote:
> > > SMP-only barriers were missing in checkpatch.pl
> > > 
> > > Refactor code slightly to make adding more variants easier.
> > []
> > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
> > If I use a variable called $smp_barriers, I'd expect
> > it to actually be the smp_barriers, not to have to
> > prefix it with smp_ before using it.
> > 
> > 		my $smp_barriers = qr{
> > 			smp_store_release|
> > 			smp_load_acquire|
> > 			smp_store_mb|
> > 			smp_read_barrier_depends
> 
> That's missing (?:barriers) too.
My version has it but need to add ?: to avoid
a capture group.
> btw: shouldn't this also have
> 	smp_mb__(?:before|after)_atomic
> ?
Good catch, included in the next version.

-- 
MST