linux-kernel - [PATCH v2] module: Fix selfAssignment cppcheck warning

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Date:   Sun, 12 Jun 2022 17:21:56 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Luis Chamberlain <mcgrof@...nel.org>, linux-modules@...r.kernel.org
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: [PATCH v2] module: Fix selfAssignment cppcheck warning

cppcheck reports the following warnings:

kernel/module/main.c:1455:26: warning: Redundant assignment of 'mod->core_layout.size' to itself. [selfAssignment]
   mod->core_layout.size = strict_align(mod->core_layout.size);
                         ^
kernel/module/main.c:1489:26: warning: Redundant assignment of 'mod->init_layout.size' to itself. [selfAssignment]
   mod->init_layout.size = strict_align(mod->init_layout.size);
                         ^
kernel/module/main.c:1493:26: warning: Redundant assignment of 'mod->init_layout.size' to itself. [selfAssignment]
   mod->init_layout.size = strict_align(mod->init_layout.size);
                         ^
kernel/module/main.c:1504:26: warning: Redundant assignment of 'mod->init_layout.size' to itself. [selfAssignment]
   mod->init_layout.size = strict_align(mod->init_layout.size);
                         ^
kernel/module/main.c:1459:26: warning: Redundant assignment of 'mod->data_layout.size' to itself. [selfAssignment]
   mod->data_layout.size = strict_align(mod->data_layout.size);
                         ^
kernel/module/main.c:1463:26: warning: Redundant assignment of 'mod->data_layout.size' to itself. [selfAssignment]
   mod->data_layout.size = strict_align(mod->data_layout.size);
                         ^
kernel/module/main.c:1467:26: warning: Redundant assignment of 'mod->data_layout.size' to itself. [selfAssignment]
   mod->data_layout.size = strict_align(mod->data_layout.size);
                         ^

This is due to strict_align() being a no-op when
CONFIG_STRICT_MODULE_RWX is not selected.

Transform strict_align() macro into an inline function. It will
allow type checking and avoid the selfAssignment warning.

Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 kernel/module/internal.h | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index bc5507ab8450..ec104c2950c3 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -11,6 +11,7 @@
 #include <linux/mutex.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
+#include <linux/mm.h>
 
 #ifndef ARCH_SHF_SMALL
 #define ARCH_SHF_SMALL 0
@@ -30,11 +31,13 @@
  * to ensure complete separation of code and data, but
  * only when CONFIG_STRICT_MODULE_RWX=y
  */
-#ifdef CONFIG_STRICT_MODULE_RWX
-# define strict_align(X) PAGE_ALIGN(X)
-#else
-# define strict_align(X) (X)
-#endif
+static inline unsigned int strict_align(unsigned int size)
+{
+	if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		return PAGE_ALIGN(size);
+	else
+		return size;
+}
 
 extern struct mutex module_mutex;
 extern struct list_head modules;
-- 
2.35.3