linux-kernel - Re: [PATCH] sched: simplify sched_init

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Message-ID: <aH37LDGeNHoT9abR@linux.ibm.com>
Date: Mon, 21 Jul 2025 14:02:44 +0530
From: Srikar Dronamraju <srikar@...ux.ibm.com>
To: Yury Norov <yury.norov@...il.com>
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>,
        Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched: simplify sched_init_numa()

* Yury Norov <yury.norov@...il.com> [2025-07-19 17:07:51]:

> From: Yury Norov (NVIDIA) <yury.norov@...il.com>
> 
> The function opencodes for_each_set_bit() macro.
> 
> Signed-off-by: Yury Norov (NVIDIA) <yury.norov@...il.com>
> ---
>  kernel/sched/topology.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index b958fe48e020..7dc3c79aa480 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -1932,10 +1932,9 @@ void sched_init_numa(int offline_node)
>  		return;
>  	}
>  
> -	for (i = 0, j = 0; i < nr_levels; i++, j++) {
> -		j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
> -		distances[i] = j;
> -	}
> +	for_each_set_bit(j, distance_map, NR_DISTANCE_VALUES)
> +		distances[i++] = j;
> +

Dont we need to reset the value of i;

Also now we may be iterating for NR_DISTANCE_VALUES instead of nr_levels.
It should be okay, since NR_DISTANCE_VALUES is just 8.

>  	rcu_assign_pointer(sched_domains_numa_distance, distances);
>  
>  	bitmap_free(distance_map);
> -- 
> 2.43.0
> 

-- 
Thanks and Regards
Srikar Dronamraju