linux-kernel - [PATCH v2] once: Don't use a work queue to reset sleepable static key

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Message-ID: <aWU4tfTju1l3oZCu@agluck-desk3>
Date: Mon, 12 Jan 2026 10:08:53 -0800
From: "Luck, Tony" <tony.luck@...el.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: Eric Dumazet <edumazet@...gle.com>, Reinette Chatre
	<reinette.chatre@...el.com>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: [PATCH v2] once: Don't use a work queue to reset sleepable static key

Pointless overhead to use a work queue to reset the static key
for a DO_ONCE_SLEEPABLE() invocation.

Note that the previous code path included a BUG_ON() if the static key
was already disabled. Dropped that as part of this change because:
1) Use of BUG_ON() is highly discouraged.
2) There is a WARN_ON() in the static_branch_disable() code path
   that would provide adequate breadcrumbs to debug any issue.

Reported-by: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
Changes since v1:
Andrew Morton pointed out that adding a new BUG_ON() was ill-advised.
Drop it (but explain why it isn't needed in the commit message).

 lib/once.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/once.c b/lib/once.c
index 2c306f0e891e..8557eb489f34 100644
--- a/lib/once.c
+++ b/lib/once.c
@@ -93,6 +93,6 @@ 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);
+	static_branch_disable(once_key);
 }
 EXPORT_SYMBOL(__do_once_sleepable_done);
-- 
2.52.0