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>

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 94b4e33fa532d37d71582000b609a01d7925e505..25476c29bb18e9db18defbc3a4e8ed3825952357 100755 (executable)
--- 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)) {