[PATCH v9 04/12] arm64: support WFET in smp_cond_load_relaxed_timeout()

[Catalin Marinas]

On Sun, Feb 08, 2026 at 06:31:45PM -0800, Ankur Arora wrote:
> diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
> index d7a540736741..dfb7d10a18be 100644
> --- a/arch/arm64/include/asm/cmpxchg.h
> +++ b/arch/arm64/include/asm/cmpxchg.h
> @@ -12,6 +12,7 @@
>  
>  #include <asm/barrier.h>
>  #include <asm/lse.h>
> +#include <asm/delay-const.h>
>  
>  /*
>   * We need separate acquire parameters for ll/sc and lse, since the full
> @@ -208,9 +209,13 @@ __CMPXCHG_GEN(_mb)
>  	__cmpxchg128((ptr), (o), (n));						\
>  })
>  
> +/* Re-declared here to avoid include dependency. */
> +extern u64 (*arch_timer_read_counter)(void);

We have a bug in udelay() because the above might read the physical
counter while WFET uses the virtual one. See this thread:

https://lore.kernel.org/all/ktosachvft2cgqd5qkukn275ugmhy6xrhxur4zqpdxlfr3qh5h@o3zrfnsq63od/

We could use __arch_counter_get_cntvct_stable() as in Marc's suggestion
for the udelay() fix (or just wait to see the outcome of the above
thread).

The rest looks fine.

-- 
Catalin