linux-kernel - Re: [PATCH] once: Don't use a work queue to reset sleepable static key

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Message-Id: <20260110185444.3ccd7f6cf8b1bd319d3fa80b@linux-foundation.org>
Date: Sat, 10 Jan 2026 18:54:44 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Tony Luck <tony.luck@...el.com>
Cc: Eric Dumazet <edumazet@...gle.com>, Reinette Chatre
 <reinette.chatre@...el.com>, linux-kernel@...r.kernel.org,
 patches@...ts.linux.dev
Subject: Re: [PATCH] once: Don't use a work queue to reset sleepable static
 key

On Thu,  8 Jan 2026 15:27:17 -0800 Tony Luck <tony.luck@...el.com> wrote:

> Pointless overhead to use a work queue to reset the static key
> for a DO_ONCE_SLEEPABLE() invocation.
> 
> ...
>
> --- a/lib/once.c
> +++ b/lib/once.c
> @@ -93,6 +93,7 @@ void __do_once_sleepable_done(bool *done, struct static_key_true *once_key,
>  {
>  	*done = true;
>  	mutex_unlock(&once_mutex);
> -	once_disable_jump(once_key, mod);
> +	BUG_ON(!static_key_enabled(once_key));

Sauron's eye is upon us.  Can we either justify nuking the kernel or
use a WARN_ON?

> +	static_branch_disable(once_key);
>  }
>  EXPORT_SYMBOL(__do_once_sleepable_done);
> -- 
> 2.52.0