linux-kernel - [PATCH] of: declare string literals const

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Date:   Wed, 12 Oct 2022 19:46:22 +0200
From:   Christian Göttsche <cgzones@...glemail.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH] of: declare string literals const

of_overlay_action_name() returns a string literal from a function local
array.  Modifying string literals is undefined behavior which usage of
const pointer can avoid.  of_overlay_action_name() is currently only
used once in overlay_notify() to print the returned value.

While on it declare the data array const as well.

Reported by Clang:

    In file included from arch/x86/kernel/asm-offsets.c:22:
    In file included from arch/x86/kernel/../kvm/vmx/vmx.h:5:
    In file included from ./include/linux/kvm_host.h:19:
    In file included from ./include/linux/msi.h:23:
    In file included from ./arch/x86/include/asm/msi.h:5:
    In file included from ./arch/x86/include/asm/irqdomain.h:5:
    In file included from ./include/linux/irqdomain.h:35:
    ./include/linux/of.h:1555:3: error: initializing 'char *' with an expression of type 'const char[5]' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
                    "init",
                    ^~~~~~
    ./include/linux/of.h:1556:3: error: initializing 'char *' with an expression of type 'const char[10]' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
                    "pre-apply",
                    ^~~~~~~~~~~
    ./include/linux/of.h:1557:3: error: initializing 'char *' with an expression of type 'const char[11]' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
                    "post-apply",
                    ^~~~~~~~~~~~
    ./include/linux/of.h:1558:3: error: initializing 'char *' with an expression of type 'const char[11]' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
                    "pre-remove",
                    ^~~~~~~~~~~~
    ./include/linux/of.h:1559:3: error: initializing 'char *' with an expression of type 'const char[12]' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
                    "post-remove",
                    ^~~~~~~~~~~~~

Signed-off-by: Christian Göttsche <cgzones@...glemail.com>
---
 include/linux/of.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/of.h b/include/linux/of.h
index 6b79ef9a6541..8b9f94386dc3 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -1549,9 +1549,9 @@ enum of_overlay_notify_action {
 	OF_OVERLAY_POST_REMOVE,
 };
 
-static inline char *of_overlay_action_name(enum of_overlay_notify_action action)
+static inline const char *of_overlay_action_name(enum of_overlay_notify_action action)
 {
-	static char *of_overlay_action_name[] = {
+	static const char *const of_overlay_action_name[] = {
 		"init",
 		"pre-apply",
 		"post-apply",
-- 
2.37.2