From: Utkarsh Verma <utkarshverma294@gmail.com>
Date: Sat, 4 Sep 2021 07:42:01 +0000 (+0530)
Subject: Documentation: checkpatch: Add TRAILING_SEMICOLON message
X-Git-Tag: v5.16-rc1~136^2~48
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=29bd0cace2351eeccf325e36756aa55aa939bd11;p=thirdparty%2Fkernel%2Flinux.git

Documentation: checkpatch: Add TRAILING_SEMICOLON message

Add a new message type TRAILING_SEMICOLON for the macro definitions
that conclude with a semicolon.

Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Utkarsh Verma <utkarshverma294@gmail.com>
Link: https://lore.kernel.org/r/20210904074201.13532-1-utkarshverma294@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
---

diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
index b7a1288e96a92..891779c7f0bf6 100644
--- a/Documentation/dev-tools/checkpatch.rst
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -851,6 +851,27 @@ Macros, Attributes and Symbols
     Use the `fallthrough;` pseudo keyword instead of
     `/* fallthrough */` like comments.
 
+  **TRAILING_SEMICOLON**
+    Macro definition should not end with a semicolon. The macro
+    invocation style should be consistent with function calls.
+    This can prevent any unexpected code paths::
+
+      #define MAC do_something;
+
+    If this macro is used within a if else statement, like::
+
+      if (some_condition)
+              MAC;
+
+      else
+              do_something;
+
+    Then there would be a compilation error, because when the macro is
+    expanded there are two trailing semicolons, so the else branch gets
+    orphaned.
+
+    See: https://lore.kernel.org/lkml/1399671106.2912.21.camel@joe-AO725/
+
   **WEAK_DECLARATION**
     Using weak declarations like __attribute__((weak)) or __weak
     can have unintended link defects.  Avoid using them.