checkpatch: check for __smp outside barrier.h

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@arm.linux.org.uk>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Julian Calaby <julian.calaby@gmail.com>
Acked-by: Joe Perches <joe@perches.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 94b4e33fa532..25476c29bb18 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5143,6 +5143,16 @@ sub process {
                         }
                 }
 
+                my $underscore_smp_barriers = qr{__smp_(?:$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)) {