Linux Virtualization - Jan 2016 - [PATCH v3 0/3] checkpatch: handling of memory barriers

As part of memory barrier cleanup, this patchset
extends checkpatch to make it easier to stop
incorrect memory barrier usage.

This replaces the checkpatch patches in my series
	arch: barrier cleanup + barriers for virt
and will be included in the next version of the series.

changes from v2:
	address comments by Joe Perches:
	use (?: ... ) to avoid unnecessary capture groups
	rename smp_barriers to smp_barrier_stems for clarity
	add barriers before/after atomic
Changes from v1:
	catch optional\s* before () in barriers
	rewrite using qr{} instead of map

Michael S. Tsirkin (3):
  checkpatch.pl: add missing memory barriers
  checkpatch: check for __smp outside barrier.h
  checkpatch: add virt barriers

 scripts/checkpatch.pl | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

-- 
MST

SMP-only barriers were missing in checkpatch.pl

Refactor code slightly to make adding more variants easier.

Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
---
 scripts/checkpatch.pl | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 2b3c228..1c01b7d 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5116,7 +5116,27 @@ 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 $smp_barrier_stems = qr{
+			mb__before_atomic|
+			mb__after_atomic|
+			store_release|
+			load_acquire|
+			store_mb|
+			(?:$barriers)
+		}x;
+		my $all_barriers = qr{
+			$barriers|
+			smp_(?:$smp_barrier_stems)
+		}x;
+
+		if ($line =~ /\b(?:$all_barriers)\s*\(/) {
 			if (!ctx_has_comment($first_line, $linenr)) {
 				WARN("MEMORY_BARRIER",
 				     "memory barrier without comment\n" . $herecurr);
-- 
MST

Introduction of __smp barriers cleans up a bunch of duplicate code, but
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 (as happened with other arch stuff before.)

Add a checkpatch test so it will trigger a warning.

Reported-by: Russell King <linux at arm.linux.org.uk>
Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
---
 scripts/checkpatch.pl | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 1c01b7d..15cfca4 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5143,6 +5143,16 @@ sub process {
 			}
 		}
 
+		my $underscore_smp_barriers = qr{__smp_(?:$smp_barrier_stems)}x;
+
+		if ($realfile !~ m@^include/asm-generic/@ &&
+		    $realfile !~ m@/barrier\.h$@ &&
+		    $line =~ m/\b(?:$underscore_smp_barriers)\s*\(/ &&
+		    $line !~ m/^.\s*\#\s*define\s+(?:$underscore_smp_barriers)\s*\(/) {
+			WARN("MEMORY_BARRIER",
+			     "__smp memory barriers shouldn't be used outside barrier.h and
asm-generic\n" . $herecurr);
+		}
+
 # check for waitqueue_active without a comment.
 		if ($line =~ /\bwaitqueue_active\s*\(/) {
 			if (!ctx_has_comment($first_line, $linenr)) {
-- 
MST

Add virt_ barriers to list of barriers to check for
presence of a comment.

Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
---
 scripts/checkpatch.pl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 15cfca4..4466579 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5133,7 +5133,8 @@ sub process {
 		}x;
 		my $all_barriers = qr{
 			$barriers|
-			smp_(?:$smp_barrier_stems)
+			smp_(?:$smp_barrier_stems)|
+			virt_(?:$smp_barrier_stems)
 		}x;
 
 		if ($line =~ /\b(?:$all_barriers)\s*\(/) {
-- 
MST

Hi Michael,

On Mon, Jan 11, 2016 at 6:31 AM, Michael S. Tsirkin <mst at redhat.com>
wrote:
> Add virt_ barriers to list of barriers to check for
> presence of a comment.
>
> Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
> ---
>  scripts/checkpatch.pl | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 15cfca4..4466579 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -5133,7 +5133,8 @@ sub process {
>                 }x;
>                 my $all_barriers = qr{
>                         $barriers|
> -                       smp_(?:$smp_barrier_stems)
> +                       smp_(?:$smp_barrier_stems)|
> +                       virt_(?:$smp_barrier_stems)
Sorry I'm late to the party here, but would it make sense to write this as:

(?:smp|virt)_(?:$smp_barrier_stems)

Thanks,

-- 
Julian Calaby

Email: julian.calaby at gmail.com
Profile: http://www.google.com/profiles/julian.calaby/