of: declare string literals const

PATCH Applied Christian Göttsche 4 participants 4 messages Oct 12, 2022 – Oct 14, 2022 Device tree

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Christian Göttsche

author

2022-10-12 17:46 UTC #0 lore raw

PATCH 1/1 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 <[email protected]>

---
 include/linux/of.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

include/linux/of.h +2 -2

index 6b79ef9a6541..8b9f94386dc3 100644
@@ -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",

Signature · 1 line

2.37.2

Nick Desaulniers

Reviewed-by on v1 1/1

2022-10-13 20:57 UTC #1 lore raw

Quoted 33 lines · Christian Göttsche

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",
^~~~~~~~~~~~~

Quoted 1 line

Signed-off-by Christian Göttsche <[email protected]>

Thanks for the patch!

Reviewed-by Nick Desaulniers <[email protected]>

Quoted 23 lines

---
 include/linux/of.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

include/linux/of.h +2 -3

index 6b79ef9a6541..8b9f94386dc3 100644
@@ -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

Signature · 2 lines

Thanks,
~Nick Desaulniers

Frank Rowand

Reviewed-by on v1 1/1

2022-10-14 18:42 UTC #2 lore raw

In reply to Christian Göttsche

Quoted 43 lines · Christian Göttsche

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 <[email protected]>
---
 include/linux/of.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
include/linux/of.h +0 -0
index 6b79ef9a6541..8b9f94386dc3 100644
@@ -1549,9 +1549,9 @@ enum of_overlay_notify_action {
 	OF_OVERLAY_POST_REMOVE,

include/linux/of.h enum of_overlay_notify_action { · line 1557

Quoted 10 lines

include/linux/of.h +2 -2

 };
 
-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",

Reviewed-by Frank Rowand <[email protected]>

Rob Herring

maintainer Applied

2022-10-14 21:11 UTC #3 lore raw

In reply to Christian Göttsche

Quoted 32 lines · Christian Göttsche

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",
^~~~~~~~~~~~~

Quoted 5 lines

Signed-off-by Christian Göttsche <[email protected]>
---
 include/linux/of.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Applied, thanks!