checkpatch: add a test for const with __read_mostly uses

const objects shouldn't be __read_mostly.  They are read-only.

Marking these objects as __read_mostly causes section conflicts with LTO
linking.

So add a test to try to avoid this issue.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 78a951f..2851658 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4791,6 +4791,16 @@ sub process {
                        }
                }
 
+# check for __read_mostly with const non-pointer (should just be const)
+               if ($line =~ /\b__read_mostly\b/ &&
+                   $line =~ /($Type)\s*$Ident/ && $1 !~ /\*\s*$/ && $1 =~ /\bconst\b/) {
+                       if (ERROR("CONST_READ_MOSTLY",
+                                 "Invalid use of __read_mostly with const type\n" . $herecurr) &&
+                           $fix) {
+                               $fixed[$fixlinenr] =~ s/\s+__read_mostly\b//;
+                       }
+               }
+
 # don't use __constant_<foo> functions outside of include/uapi/
                if ($realfile !~ m@^include/uapi/@ &&
                    $line =~ /(__constant_(?:htons|ntohs|[bl]e(?:16|32|64)_to_cpu|cpu_to_[bl]e(?:16|32|64)))\s*\(/) {