Re: [PATCH 1/4] locking/qspinlock: Fix 'wait_early' set but not used warning

[Boqun Feng]

On Mon, Feb 12, 2024 at 10:16:53PM -0500, Waiman Long wrote:
> When CONFIG_LOCK_EVENT_COUNTS is off, the wait_early variable will be
> set but not used. This is expected. Recent compilers will not generate
> wait_early code in this case.
> 
> Add the __maybe_unused attribute to wait_early for suppressing this
> W=1 warning.
> 
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202312260422.f4pK3f9m-lkp@xxxxxxxxx/
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>

Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx>

Regards,
Boqun

> ---
>  kernel/locking/qspinlock_paravirt.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
> index 6a0184e9c234..ae2b12f68b90 100644
> --- a/kernel/locking/qspinlock_paravirt.h
> +++ b/kernel/locking/qspinlock_paravirt.h
> @@ -294,8 +294,8 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
>  {
>  	struct pv_node *pn = (struct pv_node *)node;
>  	struct pv_node *pp = (struct pv_node *)prev;
> +	bool __maybe_unused wait_early;
>  	int loop;
> -	bool wait_early;
>  
>  	for (;;) {
>  		for (wait_early = false, loop = SPIN_THRESHOLD; loop; loop--) {
> -- 
> 2.39.3
>