Re: [PATCH 1/3] powerpc/spinlocks: Refactor SHARED_PROCESSOR

[Thiago Jung Bauermann <bauerman@linux.ibm.com>]

Christopher M. Riedl <cmr@informatik.wtf> writes:

> Determining if a processor is in shared processor mode is not a constant
> so don't hide it behind a #define.
>
> Signed-off-by: Christopher M. Riedl <cmr@informatik.wtf>
> ---
>  arch/powerpc/include/asm/spinlock.h | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h
> index a47f827bc5f1..8631b0b4e109 100644
> --- a/arch/powerpc/include/asm/spinlock.h
> +++ b/arch/powerpc/include/asm/spinlock.h
> @@ -101,15 +101,24 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock)
>
>  #if defined(CONFIG_PPC_SPLPAR)
>  /* We only yield to the hypervisor if we are in shared processor mode */
> -#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca->lppaca_ptr))
>  extern void __spin_yield(arch_spinlock_t *lock);
>  extern void __rw_yield(arch_rwlock_t *lock);
>  #else /* SPLPAR */
>  #define __spin_yield(x)	barrier()
>  #define __rw_yield(x)	barrier()
> -#define SHARED_PROCESSOR	0
>  #endif
>
> +static inline bool is_shared_processor(void)
> +{
> +/* Only server processors have an lppaca struct */
> +#ifdef CONFIG_PPC_BOOK3S
> +	return (IS_ENABLED(CONFIG_PPC_SPLPAR) &&
> +		lppaca_shared_proc(local_paca->lppaca_ptr));
> +#else
> +	return false;
> +#endif
> +}
> +

CONFIG_PPC_SPLPAR depends on CONFIG_PPC_PSERIES, which depends on
CONFIG_PPC_BOOK3S so the #ifdef above is unnecessary:

if CONFIG_PPC_BOOK3S is unset then CONFIG_PPC_SPLPAR will be unset as
well and the return expression should short-circuit to false.

--
Thiago Jung Bauermann
IBM Linux Technology Center