Re: [PATCH 1/3] sched/fair: Use guard in sched_group_set_idle()

[Kayra Cizmeci <kayracizmeci@gmail.com>]

Hi Peter,

On Thu, Nov 05, 2026 at 05:55:26PM +0100, Peter Zijlstra wrote:

> Cleanup the code by using guards; prepares for further changes in this function.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
>  kernel/sched/fair.c |   16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
> 
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -15790,12 +15790,9 @@ int sched_group_set_idle(struct task_gro
>  	if (idle < 0 || idle > 1)
>  		return -EINVAL;
>  
> -	mutex_lock(&shares_mutex);
> -
> -	if (tg->idle == idle) {
> -		mutex_unlock(&shares_mutex);
> +	guard(mutex)(&shares_mutex);
> +	if (tg->idle == idle)
>  		return 0;
> -	}
>  
>  	tg->idle = idle;
>  
> @@ -15805,13 +15802,12 @@ int sched_group_set_idle(struct task_gro
>  		struct cfs_rq *grp_cfs_rq = tg_cfs_rq(tg, i);
>  		bool was_idle = cfs_rq_is_idle(grp_cfs_rq);
>  		long idle_task_delta;
> -		struct rq_flags rf;
>  
> -		rq_lock_irqsave(rq, &rf);
> +		guard(rq_lock_irqsave)(rq);
>  
>  		grp_cfs_rq->idle = idle;
>  		if (WARN_ON_ONCE(was_idle == cfs_rq_is_idle(grp_cfs_rq)))
> -			goto next_cpu;
> +			continue;
>  
>  		idle_task_delta = grp_cfs_rq->h_nr_queued -
>  				  grp_cfs_rq->h_nr_idle;
> @@ -15830,9 +15826,6 @@ int sched_group_set_idle(struct task_gro
>  			if (cfs_rq_is_idle(cfs_rq))
>  				break;
>  		}
> -
> -next_cpu:
> -		rq_unlock_irqrestore(rq, &rf);
>  	}
>  
>  	/* Idle groups have minimum weight. */
> @@ -15841,7 +15834,6 @@ int sched_group_set_idle(struct task_gro
>  	else
>  		__sched_group_set_shares(tg, NICE_0_LOAD);
>  
> -	mutex_unlock(&shares_mutex);
>  	return 0;
>  }
>  
> 
> 

LGTM.

Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>


Cheers,

Kayra