[PATCH] efi: Constify sysfs attributes

[PATCH] efi: Constify sysfs attributes

[Ard Biesheuvel]

From: Ard Biesheuvel <ardb@kernel.org>

Implement Thomas's suggestions to constify sysfs kobject attributes.

Cc: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/platform/efi/efi.c | 11 ++++---
 drivers/firmware/efi/efi.c  | 34 +++++++++++---------
 include/linux/efi.h         |  3 +-
 3 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 0c39adb96b91..d8fe93770c2a 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -891,7 +891,7 @@ bool efi_is_table_address(unsigned long phys_addr)
 
 #define EFI_ATTR_SHOW(name) \
 static ssize_t name##_show(struct kobject *kobj, \
-				struct kobj_attribute *attr, char *buf) \
+			   const struct kobj_attribute *attr, char *buf) \
 { \
 	return sprintf(buf, "0x%lx\n", EFI_FIELD(name)); \
 }
@@ -900,11 +900,12 @@ EFI_ATTR_SHOW(fw_vendor);
 EFI_ATTR_SHOW(runtime);
 EFI_ATTR_SHOW(config_table);
 
-struct kobj_attribute efi_attr_fw_vendor = __ATTR_RO(fw_vendor);
-struct kobj_attribute efi_attr_runtime = __ATTR_RO(runtime);
-struct kobj_attribute efi_attr_config_table = __ATTR_RO(config_table);
+const struct kobj_attribute efi_attr_fw_vendor = __KOBJ_ATTR_RO(fw_vendor);
+const struct kobj_attribute efi_attr_runtime = __KOBJ_ATTR_RO(runtime);
+const struct kobj_attribute efi_attr_config_table = __KOBJ_ATTR_RO(config_table);
 
-umode_t efi_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
+umode_t efi_attr_is_visible(struct kobject *kobj, const struct attribute *attr,
+			    int n)
 {
 	if (attr == &efi_attr_fw_vendor.attr) {
 		if (efi_enabled(EFI_PARAVIRT) ||
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index e08ce813a3d4..93d6ffd9bc0d 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -155,21 +155,21 @@ static ssize_t systab_show(struct kobject *kobj,
 	return str - buf;
 }
 
-static struct kobj_attribute efi_attr_systab = __ATTR_RO_MODE(systab, 0400);
+static const struct kobj_attribute efi_attr_systab = __ATTR_RO_MODE(systab, 0400);
 
 static ssize_t fw_platform_size_show(struct kobject *kobj,
-				     struct kobj_attribute *attr, char *buf)
+				     const struct kobj_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%d\n", efi_enabled(EFI_64BIT) ? 64 : 32);
 }
 
-extern __weak struct kobj_attribute efi_attr_fw_vendor;
-extern __weak struct kobj_attribute efi_attr_runtime;
-extern __weak struct kobj_attribute efi_attr_config_table;
-static struct kobj_attribute efi_attr_fw_platform_size =
-	__ATTR_RO(fw_platform_size);
+extern __weak const struct kobj_attribute efi_attr_fw_vendor;
+extern __weak const struct kobj_attribute efi_attr_runtime;
+extern __weak const struct kobj_attribute efi_attr_config_table;
+static const struct kobj_attribute efi_attr_fw_platform_size =
+	__KOBJ_ATTR_RO(fw_platform_size);
 
-static struct attribute *efi_subsys_attrs[] = {
+static const struct attribute *const efi_subsys_attrs[] = {
 	&efi_attr_systab.attr,
 	&efi_attr_fw_platform_size.attr,
 	&efi_attr_fw_vendor.attr,
@@ -178,15 +178,16 @@ static struct attribute *efi_subsys_attrs[] = {
 	NULL,
 };
 
-umode_t __weak efi_attr_is_visible(struct kobject *kobj, struct attribute *attr,
+umode_t __weak efi_attr_is_visible(struct kobject *kobj,
+				   const struct attribute *attr,
 				   int n)
 {
 	return attr->mode;
 }
 
 static const struct attribute_group efi_subsys_attr_group = {
-	.attrs = efi_subsys_attrs,
-	.is_visible = efi_attr_is_visible,
+	.attrs_const = efi_subsys_attrs,
+	.is_visible_const = efi_attr_is_visible,
 };
 
 struct blocking_notifier_head efivar_ops_nh;
@@ -401,12 +402,15 @@ static void __init efi_debugfs_init(void)
 static inline void efi_debugfs_init(void) {}
 #endif
 
-static ssize_t efi_runtime_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+static ssize_t efi_runtime_show(struct kobject *kobj,
+				const struct kobj_attribute *attr,
+				char *buf)
 {
 	return sprintf(buf, "%d\n", efi_enabled(EFI_RUNTIME_SERVICES));
 }
 
-static ssize_t efi_runtime_store(struct kobject *kobj, struct kobj_attribute *attr,
+static ssize_t efi_runtime_store(struct kobject *kobj,
+				 const struct kobj_attribute *attr,
 				 const char *buf, size_t count)
 {
 	int ret;
@@ -424,8 +428,8 @@ static ssize_t efi_runtime_store(struct kobject *kobj, struct kobj_attribute *at
 	return count;
 }
 
-static struct kobj_attribute efi_runtime_attr =
-	__ATTR(runtime_enable, 0644, efi_runtime_show, efi_runtime_store);
+static const struct kobj_attribute efi_runtime_attr =
+	__KOBJ_ATTR(runtime_enable, 0644, efi_runtime_show, efi_runtime_store);
 
 static int __init efipostcore_init(void)
 {
diff --git a/include/linux/efi.h b/include/linux/efi.h
index ecb34be37a87..fda81d7c4850 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1353,7 +1353,8 @@ bool efi_config_table_is_usable(const efi_guid_t *guid, unsigned long table)
 	return xen_efi_config_table_is_usable(guid, table);
 }
 
-umode_t efi_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n);
+umode_t efi_attr_is_visible(struct kobject *kobj, const struct attribute *attr,
+			    int n);
 
 int ovmf_log_probe(unsigned long ovmf_debug_log_table);
 
-- 
2.56.0.360.g66cac248cb-goog

Re: [PATCH] efi: Constify sysfs attributes

[Thomas Weißschuh]

On 2026-10-07 17:51:31+0200, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
> 
> Implement Thomas's suggestions to constify sysfs kobject attributes.
> 
> Cc: Thomas Weißschuh <linux@weissschuh.net>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Thanks! But some remarks.

> ---
>  arch/x86/platform/efi/efi.c | 11 ++++---
>  drivers/firmware/efi/efi.c  | 34 +++++++++++---------
>  include/linux/efi.h         |  3 +-
>  3 files changed, 27 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 0c39adb96b91..d8fe93770c2a 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -891,7 +891,7 @@ bool efi_is_table_address(unsigned long phys_addr)
>  
>  #define EFI_ATTR_SHOW(name) \
>  static ssize_t name##_show(struct kobject *kobj, \
> -				struct kobj_attribute *attr, char *buf) \
> +			   const struct kobj_attribute *attr, char *buf) \
>  { \
>  	return sprintf(buf, "0x%lx\n", EFI_FIELD(name)); \
>  }
> @@ -900,11 +900,12 @@ EFI_ATTR_SHOW(fw_vendor);
>  EFI_ATTR_SHOW(runtime);
>  EFI_ATTR_SHOW(config_table);
>  
> -struct kobj_attribute efi_attr_fw_vendor = __ATTR_RO(fw_vendor);
> -struct kobj_attribute efi_attr_runtime = __ATTR_RO(runtime);
> -struct kobj_attribute efi_attr_config_table = __ATTR_RO(config_table);
> +const struct kobj_attribute efi_attr_fw_vendor = __KOBJ_ATTR_RO(fw_vendor);
> +const struct kobj_attribute efi_attr_runtime = __KOBJ_ATTR_RO(runtime);
> +const struct kobj_attribute efi_attr_config_table = __KOBJ_ATTR_RO(config_table);
>  
> -umode_t efi_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
> +umode_t efi_attr_is_visible(struct kobject *kobj, const struct attribute *attr,
> +			    int n)

The break looks unnecessary.

>  {
>  	if (attr == &efi_attr_fw_vendor.attr) {
>  		if (efi_enabled(EFI_PARAVIRT) ||
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index e08ce813a3d4..93d6ffd9bc0d 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -155,21 +155,21 @@ static ssize_t systab_show(struct kobject *kobj,
>  	return str - buf;
>  }
>  
> -static struct kobj_attribute efi_attr_systab = __ATTR_RO_MODE(systab, 0400);
> +static const struct kobj_attribute efi_attr_systab = __ATTR_RO_MODE(systab, 0400);

__KOBJ_ATTR_RO_MODE()

(and the callback prototype)

>  static ssize_t fw_platform_size_show(struct kobject *kobj,
> -				     struct kobj_attribute *attr, char *buf)
> +				     const struct kobj_attribute *attr, char *buf)
>  {
>  	return sprintf(buf, "%d\n", efi_enabled(EFI_64BIT) ? 64 : 32);

This should switch to sysfs_emit() at some point.

>  }

(...)