From nobody Thu Oct 2 10:53:54 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BC80630216D; Thu, 18 Sep 2025 10:17:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758190674; cv=none; b=itai4g0MUG8qUk3eX/lfxrmfOJzp+qc+9eEroSihuimimnpjRaSoFZR9d+e3VkE/cy4WqKB3dfUgqR37sGRGCjxrEZkBKDHeAp6RNVOU/ebvHB6fVrA2uP1MVYN2xOPTfE18gAdyf4WKmfghzE4ObXzd6r12DDt+FhG0wurgewE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758190674; c=relaxed/simple; bh=tt2fnvxyKHuxMWduq2G5iWtwAxgOUA1tzVmzIKN+kzc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=HfLVCandQuN4vIoufp8TWjyeS77+l26EATyGucuOHUTb1MVveqSF5u1eZ/VUkHGibQ13PW5AlUydSCv0gN3ZCWp7KYzNXV/x985JfOwpuvvuXhXn4dGX0vMZfD05MmJDkQuhomOTOWKWbEYMP/sPgA14mSnCwehi4Ud5/l0wS6U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UIPylFx9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UIPylFx9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8BCEBC4CEE7; Thu, 18 Sep 2025 10:17:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758190674; bh=tt2fnvxyKHuxMWduq2G5iWtwAxgOUA1tzVmzIKN+kzc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UIPylFx9ChvcXM7wjTxfr4qUJQo/k9aqvgOr3xgTCMA4EYzaNxzibcmUyUz6oGiso Ltj5RIOX83KZpjI8IckALIVdER+Swnyzbtd3cXwFAMbIvaWAu8M8Mp33JILJKdqel5 Of3UD3LnODF3O2zLZu2V6hq7F39/+f7KHx835Yrr08G6kOTUf46UvVkKtayTB7C9HM WdLyraTGZr5/ku1efz2XxrmFjSj//O5lm233tT57feIsIM+ZkgKvTx/rP+Ubir++4H S1+eNngmWLx4oGogohgn9ImjJYD3A/wzbGcUNpSTkUhCqFVne2A8/Vx8ECmupkZKW+ f0MC9s+ZL8CaQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 116BFCE0B32; Thu, 18 Sep 2025 03:17:54 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, "Paul E. McKenney" Subject: [PATCH v2 1/5] rcu: Document that rcu_barrier() hurries lazy callbacks Date: Thu, 18 Sep 2025 03:17:48 -0700 Message-Id: <20250918101752.2592512-1-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <3773a6e3-8ec8-48c5-9277-264cd8ccbb10@paulmck-laptop> References: <3773a6e3-8ec8-48c5-9277-264cd8ccbb10@paulmck-laptop> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This commit adds to the rcu_barrier() kerneldoc header stating that this function hurries lazy callbacks and that it does not normally result in additional RCU grace periods. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8eff357b0436be..1291e0761d70ab 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3800,6 +3800,11 @@ static void rcu_barrier_handler(void *cpu_in) * 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 perio= d. + * 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=3Dy, this function also hurries a= ll + * pending lazy RCU callbacks. */ void rcu_barrier(void) { --=20 2.40.1