From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5AE8FC54F51 for ; Wed, 29 Jul 2026 09:46:55 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B9FE010EB51; Wed, 29 Jul 2026 09:46:54 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="GngdQ3Qw"; dkim-atps=neutral Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id ECCA310EB51 for ; Wed, 29 Jul 2026 09:46:53 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id D0CE742DB1; Wed, 29 Jul 2026 09:46:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 450661F000E9; Wed, 29 Jul 2026 09:46:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785318413; bh=ES4LoSb21zgaO4ykRP24VmWuxpdtjPaJPxGZBbKvNvM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GngdQ3QwVby8uSujSIYH24y9JJ9WQGhcp/8CzYtTRRdRQGnrQlTg7nJDH/3pn69JA yWrmTf1BlUmkAQf3N7m6t4XvjIlpuy3HaDdszQhqR5CpyA8zPSMKO3fkrwzoli1/fV Kq84D/1X5IT6t4JFKV5m+NBKi0b0wkYqCAEiHuk3iatkxeuAbuYEA7+0nsFzBjyCN/ y6hLFnx6T8ay+EY6sfwRfwutos40ZaCdfiYNOVEKZBgbDnd7Ta1/X+ywVWrkAtPztz ZPVDEEkhbg9e/t3kQU1njRqTr5ppjFITDcCsDZqC/+n5T+SWkNFQVefIdltRSs3XiJ gCZ4cvfDUBHpA== From: Philipp Stanner To: Miguel Ojeda , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?UTF-8?q?Onur=20=C3=96zkan?= , Sumit Semwal , =?UTF-8?q?Christian=20K=C3=B6nig?= , Philipp Stanner , Lyude Paul , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Greg Kroah-Hartman , Asahi Lina , Burak Emir , Lorenzo Stoakes , FUJITA Tomonori , Eliot Courtney , Mirko Adzic , Timur Tabi , Daniel del Castillo , Boris Brezillon Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, rcu@vger.kernel.org Subject: [PATCH v7 3/5] rust: sync: Add abstraction for rcu_barrier() Date: Wed, 29 Jul 2026 11:45:40 +0200 Message-ID: <20260729094542.302965-5-phasta@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260729094542.302965-2-phasta@kernel.org> References: <20260729094542.302965-2-phasta@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" rcu_barrier() is a frequently used C function which is always safe to be called. Add a safe abstraction for rcu_barrier(). Signed-off-by: Philipp Stanner Tested-by: Daniel Almeida --- rust/kernel/sync/rcu.rs | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/rust/kernel/sync/rcu.rs b/rust/kernel/sync/rcu.rs index a32bef6e490b..7031ca5d2473 100644 --- a/rust/kernel/sync/rcu.rs +++ b/rust/kernel/sync/rcu.rs @@ -50,3 +50,23 @@ fn drop(&mut self) { pub fn read_lock() -> Guard { Guard::new() } + +/// Wait until all in-flight call_rcu() callbacks complete. +/// +/// Note that this primitive does not necessarily wait for an RCU grace period +/// to complete. For example, if there are no RCU callbacks queued anywhere +/// in the system, then rcu_barrier() is within its rights to return +/// immediately, without waiting for anything, much less an RCU grace period. +/// In fact, rcu_barrier() will normally not result in any RCU grace periods +/// beyond those that were already destined to be executed. +/// +/// In kernels built with CONFIG_RCU_LAZY=y, this function also hurries all +/// pending lazy RCU callbacks. +/// +/// Note that this is one of the RCU primitives which must not be called in +/// atomic context. +#[inline] +pub fn rcu_barrier() { + // SAFETY: `rcu_barrier()` is always safe to be called. It just might wait for a grace period. + unsafe { bindings::rcu_barrier() }; +} -- 2.55.0