Re: [PATCH 2/5] rseq: Move slice_ext_nsec to debugfs

[Thomas Weißschuh]

On Wed, Jan 21, 2026 at 03:24:59PM +0100, Peter Zijlstra wrote:
> Move changing the slice ext duration to debugfs, a sliglty less permanent
> interface.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---

(...)

> --- a/kernel/rseq.c
> +++ b/kernel/rseq.c
> @@ -222,12 +222,16 @@ static const struct file_operations debu
>  	.release	= single_release,
>  };
>  
> +extern void rseq_slice_ext_init(struct dentry *root_dir);

This is actually a static function.

> +
>  static int __init rseq_debugfs_init(void)
>  {
>  	struct dentry *root_dir = debugfs_create_dir("rseq", NULL);
>  
>  	debugfs_create_file("debug", 0644, root_dir, NULL, &debug_ops);
>  	rseq_stats_init(root_dir);
> +	if (IS_ENABLED(CONFIG_RSEQ_SLICE_EXTENSIO))

Missing 'N' at the end.

> +		rseq_slice_ext_init(root_dir);
>  	return 0;
>  }
>  __initcall(rseq_debugfs_init);
> @@ -515,7 +519,9 @@ struct slice_timer {
>  	void		*cookie;
>  };

(...)

> +#ifdef CONFIG_DEBUG_FS

(...)

> +#else
> +static void rseq_slice_ext_init(struct dentry *root_dir) { }
> +#endif

It might be possible to just remove the CONFIG_DEBUG_FS ifdeffery and let the
compiler optimize away all of the debugfs-related code automatically.

(...)