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Subject[PATCH v2] efi: fix -Wmissing-variable-declarations warning
From
When building x86/defconfig with Clang-18 I encounter the following warnings:
| arch/x86/platform/efi/efi.c:934:23: warning: no previous extern declaration for non-static variable 'efi_attr_fw_vendor' [-Wmissing-variable-declarations]
| 934 | struct kobj_attribute efi_attr_fw_vendor = __ATTR_RO(fw_vendor);
| arch/x86/platform/efi/efi.c:935:23: warning: no previous extern declaration for non-static variable 'efi_attr_runtime' [-Wmissing-variable-declarations]
| 935 | struct kobj_attribute efi_attr_runtime = __ATTR_RO(runtime);
| arch/x86/platform/efi/efi.c:936:23: warning: no previous extern declaration for non-static variable 'efi_attr_config_table' [-Wmissing-variable-declarations]
| 936 | struct kobj_attribute efi_attr_config_table = __ATTR_RO(config_table);

These symbols are declared extern in drivers/firmware/efi/efi.c. Move
the declarations to linux/efi.h to resolve these warnings.

Also, trim a trailing space from efi_set_variable_t typedef.

Link: https://github.com/ClangBuiltLinux/linux/issues/1920
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Changes in v2:
- Don't use static. Instead move symbols to header file (thanks Ard)
- Remove duplicated warnings output from b4 (thanks Ard)
- Link to v1: https://lore.kernel.org/r/20230829-missingvardecl-efi-v1-1-13d055a55176@google.com
---
Note: build-tested.

Also, a question: Why does the compiler warn at all? The extern
declarations _do_ exist as Ard points out [1].

[1]: https://lore.kernel.org/all/CAMj1kXE_xs+wWno4G4U+6CFCOwO7JWcmNv4et5=W=ZRrQatWnQ@mail.gmail.com/
---
drivers/firmware/efi/efi.c | 3 ---
include/linux/efi.h | 6 +++++-
2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 1599f1176842..7b4e59ccf09e 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -161,9 +161,6 @@ static ssize_t fw_platform_size_show(struct kobject *kobj,
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);

diff --git a/include/linux/efi.h b/include/linux/efi.h
index ab088c662e88..32f7ca60b0e9 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -287,7 +287,7 @@ typedef efi_status_t efi_get_variable_t (efi_char16_t *name, efi_guid_t *vendor,
unsigned long *data_size, void *data);
typedef efi_status_t efi_get_next_variable_t (unsigned long *name_size, efi_char16_t *name,
efi_guid_t *vendor);
-typedef efi_status_t efi_set_variable_t (efi_char16_t *name, efi_guid_t *vendor,
+typedef efi_status_t efi_set_variable_t (efi_char16_t *name, efi_guid_t *vendor,
u32 attr, unsigned long data_size,
void *data);
typedef efi_status_t efi_get_next_high_mono_count_t (u32 *count);
@@ -632,6 +632,10 @@ typedef struct {

extern unsigned long __ro_after_init efi_rng_seed; /* RNG Seed table */

+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;
+
/*
* All runtime access to EFI goes through this structure:
*/
---
base-commit: 706a741595047797872e669b3101429ab8d378ef
change-id: 20230829-missingvardecl-efi-59306aacfed4
Best regards,
--
Justin Stitt <justinstitt@google.com>

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