[PATCH v2 1/1] x86/cpu: Mark flag_is_changeable_p() with __maybe_unused

[PATCH v2 1/1] x86/cpu: Mark flag_is_changeable_p() with __maybe_unused

[Andy Shevchenko]

When flag_is_changeable_p() is unused, it prevents kernel builds
with clang, `make W=1` and CONFIG_WERROR=y:

arch/x86/kernel/cpu/common.c:351:19: error: unused function 'flag_is_changeable_p' [-Werror,-Wunused-function]
  351 | static inline int flag_is_changeable_p(u32 flag)
      |                   ^~~~~~~~~~~~~~~~~~~~

Fix this by marking it with __maybe_unused (both cases for the sake of
symmetry).

See also commit 6863f5643dd7 ("kbuild: allow Clang to find unused static
inline functions for W=1 build").

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
v2: marked both 32- and 64-bit cases
 arch/x86/kernel/cpu/common.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index d4e539d4e158..4b35744ef9b2 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -287,7 +287,7 @@ static int __init cachesize_setup(char *str)
 __setup("cachesize=", cachesize_setup);
 
 /* Standard macro to see if a specific flag is changeable */
-static inline int flag_is_changeable_p(u32 flag)
+static inline __maybe_unused int flag_is_changeable_p(u32 flag)
 {
 	u32 f1, f2;
 
@@ -348,7 +348,7 @@ static int __init x86_serial_nr_setup(char *s)
 }
 __setup("serialnumber", x86_serial_nr_setup);
 #else
-static inline int flag_is_changeable_p(u32 flag)
+static inline __maybe_unused int flag_is_changeable_p(u32 flag)
 {
 	return 1;
 }
-- 
2.43.0.rc1.1336.g36b5255a03ac

Re: [PATCH v2 1/1] x86/cpu: Mark flag_is_changeable_p() with __maybe_unused

[Dave Hansen]

On 9/5/24 10:02, Andy Shevchenko wrote:
> When flag_is_changeable_p() is unused, it prevents kernel builds
> with clang, `make W=1` and CONFIG_WERROR=y:
> 
> arch/x86/kernel/cpu/common.c:351:19: error: unused function 'flag_is_changeable_p' [-Werror,-Wunused-function]
>   351 | static inline int flag_is_changeable_p(u32 flag)
>       |                   ^~~~~~~~~~~~~~~~~~~~
> 
> Fix this by marking it with __maybe_unused (both cases for the sake of
> symmetry).
> 
> See also commit 6863f5643dd7 ("kbuild: allow Clang to find unused static
> inline functions for W=1 build").

Maybe something like this:

	http://hansen.beer/~dave/intel/onelessifdef.patch

I assume the inlines were there to suppress the "unused" warnings in the
first place.  So, let's just 'use' them unconditionally and leave it up
to the compiler to figure it out.

Re: [PATCH v2 1/1] x86/cpu: Mark flag_is_changeable_p() with __maybe_unused

[Andy Shevchenko]

On Mon, Sep 09, 2024 at 08:35:43AM -0700, Dave Hansen wrote:
> On 9/5/24 10:02, Andy Shevchenko wrote:

...

> > arch/x86/kernel/cpu/common.c:351:19: error: unused function 'flag_is_changeable_p' [-Werror,-Wunused-function]
> >   351 | static inline int flag_is_changeable_p(u32 flag)
> >       |                   ^~~~~~~~~~~~~~~~~~~~
> > 
> > Fix this by marking it with __maybe_unused (both cases for the sake of
> > symmetry).
> > 
> > See also commit 6863f5643dd7 ("kbuild: allow Clang to find unused static
> > inline functions for W=1 build").
> 
> Maybe something like this:
> 
> 	http://hansen.beer/~dave/intel/onelessifdef.patch

Fine to me as long as the issue is solved :-) Please, submit it formally I may
test it.

-- 
With Best Regards,
Andy Shevchenko