Re: [PATCH v1 1/1] sched/fair: Mark some static const with __maybe_unused

[Waiman Long <llong@redhat.com>]

On 4/4/25 12:52 PM, Andy Shevchenko wrote:
> GCC considers that some static const defined in the lockdep_internals.h
> are unused, which prevents `make W=1` and CONFIG_WERROR=y builds:
>
> kernel/locking/lockdep_internals.h:69:28: error: ‘LOCKF_USED_IN_IRQ_READ’ defined but not used [-Werror=unused-const-variable=]
>     69 | static const unsigned long LOCKF_USED_IN_IRQ_READ =
>        |                            ^~~~~~~~~~~~~~~~~~~~~~
> kernel/locking/lockdep_internals.h:63:28: error: ‘LOCKF_ENABLED_IRQ_READ’ defined but not used [-Werror=unused-const-variable=]
>     63 | static const unsigned long LOCKF_ENABLED_IRQ_READ =
>        |                            ^~~~~~~~~~~~~~~~~~~~~~
> kernel/locking/lockdep_internals.h:57:28: error: ‘LOCKF_USED_IN_IRQ’ defined but not used [-Werror=unused-const-variable=]
>     57 | static const unsigned long LOCKF_USED_IN_IRQ =
>        |                            ^~~~~~~~~~~~~~~~~
> kernel/locking/lockdep_internals.h:51:28: error: ‘LOCKF_ENABLED_IRQ’ defined but not used [-Werror=unused-const-variable=]
>     51 | static const unsigned long LOCKF_ENABLED_IRQ =
>        |                            ^~~~~~~~~~~~~~~~~
>
> Fix this by marking them with __maybe_unused.

The code changes look good, but the "sched/fair" heading is misleading. 
It is not related to scheduler at all, it should be "locking/lockdep" or 
just "lockdep".

Cheers,
Longman

>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>   kernel/locking/lockdep_internals.h | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
> index 20f9ef58d3d0..82e71335f367 100644
> --- a/kernel/locking/lockdep_internals.h
> +++ b/kernel/locking/lockdep_internals.h
> @@ -48,25 +48,25 @@ enum {
>   };
>   
>   #define LOCKDEP_STATE(__STATE)	LOCKF_ENABLED_##__STATE |
> -static const unsigned long LOCKF_ENABLED_IRQ =
> +static __maybe_unused const unsigned long LOCKF_ENABLED_IRQ =
>   #include "lockdep_states.h"
>   	0;
>   #undef LOCKDEP_STATE
>   
>   #define LOCKDEP_STATE(__STATE)	LOCKF_USED_IN_##__STATE |
> -static const unsigned long LOCKF_USED_IN_IRQ =
> +static __maybe_unused const unsigned long LOCKF_USED_IN_IRQ =
>   #include "lockdep_states.h"
>   	0;
>   #undef LOCKDEP_STATE
>   
>   #define LOCKDEP_STATE(__STATE)	LOCKF_ENABLED_##__STATE##_READ |
> -static const unsigned long LOCKF_ENABLED_IRQ_READ =
> +static __maybe_unused const unsigned long LOCKF_ENABLED_IRQ_READ =
>   #include "lockdep_states.h"
>   	0;
>   #undef LOCKDEP_STATE
>   
>   #define LOCKDEP_STATE(__STATE)	LOCKF_USED_IN_##__STATE##_READ |
> -static const unsigned long LOCKF_USED_IN_IRQ_READ =
> +static __maybe_unused const unsigned long LOCKF_USED_IN_IRQ_READ =
>   #include "lockdep_states.h"
>   	0;
>   #undef LOCKDEP_STATE