linux-kernel - Re: [PATCH v2 sched_ext/for-6.15-fixes] sched_ext: Mark SCX_OPS_HAS_CGROUP

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Message-ID: <Z_Vt9kWib7E5bH9K@gpd3>
Date: Tue, 8 Apr 2025 20:41:58 +0200
From: Andrea Righi <arighi@...dia.com>
To: Tejun Heo <tj@...nel.org>
Cc: David Vernet <void@...ifault.com>, Changwoo Min <changwoo@...lia.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 sched_ext/for-6.15-fixes] sched_ext: Mark
 SCX_OPS_HAS_CGROUP_WEIGHT for deprecation

On Tue, Apr 08, 2025 at 08:31:12AM -1000, Tejun Heo wrote:
> SCX_OPS_HAS_CGROUP_WEIGHT was only used to suppress the missing cgroup
> weight support warnings. Now that the warnings are removed, the flag doesn't
> do anything. Mark it for deprecation and remove its usage from scx_flatcg.
> 
> v2: Actually include the scx_flatcg update.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Suggested-by: Andrea Righi <arighi@...dia.com>

Looks good, thanks!

Reviewed-by: Andrea Righi <arighi@...dia.com>

-Andrea

> ---
>  kernel/sched/ext.c               |    5 ++++-
>  tools/sched_ext/scx_flatcg.bpf.c |    2 +-
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
> index 21eaf081d336..fdbf249d1c68 100644
> --- a/kernel/sched/ext.c
> +++ b/kernel/sched/ext.c
> @@ -163,7 +163,7 @@ enum scx_ops_flags {
>  	/*
>  	 * CPU cgroup support flags
>  	 */
> -	SCX_OPS_HAS_CGROUP_WEIGHT = 1LLU << 16,	/* cpu.weight */
> +	SCX_OPS_HAS_CGROUP_WEIGHT = 1LLU << 16,	/* DEPRECATED, will be removed on 6.18 */
>  
>  	SCX_OPS_ALL_FLAGS	= SCX_OPS_KEEP_BUILTIN_IDLE |
>  				  SCX_OPS_ENQ_LAST |
> @@ -5213,6 +5213,9 @@ static int validate_ops(const struct sched_ext_ops *ops)
>  		return -EINVAL;
>  	}
>  
> +	if (ops->flags & SCX_OPS_HAS_CGROUP_WEIGHT)
> +		pr_warn("SCX_OPS_HAS_CGROUP_WEIGHT is deprecated and a noop\n");
> +
>  	return 0;
>  }
>  
> diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
> index 2c720e3ecad5..fdc7170639e6 100644
> --- a/tools/sched_ext/scx_flatcg.bpf.c
> +++ b/tools/sched_ext/scx_flatcg.bpf.c
> @@ -950,5 +950,5 @@ SCX_OPS_DEFINE(flatcg_ops,
>  	       .cgroup_move		= (void *)fcg_cgroup_move,
>  	       .init			= (void *)fcg_init,
>  	       .exit			= (void *)fcg_exit,
> -	       .flags			= SCX_OPS_HAS_CGROUP_WEIGHT | SCX_OPS_ENQ_EXITING,
> +	       .flags			= SCX_OPS_ENQ_EXITING,
>  	       .name			= "flatcg");