checkpatch: add error on use of attribute((weak)) or __weak declarations

Using weak declarations can have unintended link defects.  The __weak on
the declaration causes non-weak definitions to become weak.

Emit an error on its use.

Signed-off-by: Joe Perches <joe@perches.com>
Reported-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 696254eee78b..8a577aa03bc6 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4671,6 +4671,15 @@ sub process {
                         }
                 }
 
+# Check for __attribute__ weak, or __weak declarations (may have link issues)
+                if ($^V && $^V ge 5.10.0 &&
+                    $line =~ /(?:$Declare|$DeclareMisordered)\s*$Ident\s*$balanced_parens\s*(?:$Attribute)?\s*;/ &&
+                    ($line =~ /\b__attribute__\s*\(\s*\(.*\bweak\b/ ||
+                     $line =~ /\b__weak\b/)) {
+                        ERROR("WEAK_DECLARATION",
+                              "Using weak declarations can have unintended link defects\n" . $herecurr);
+                }
+
 # check for sizeof(&)
                 if ($line =~ /\bsizeof\s*\(\s*\&/) {
                         WARN("SIZEOF_ADDRESS",