From nobody Sat Oct 4 14:10:46 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 7BE93482EB; Sat, 16 Aug 2025 00:01:51 +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=1755302511; cv=none; b=h+OKqgdtCZb+sILslIHYwUmErcITSWoI54QKZLCwXnOFq5qP0tv7Ymy7SWUN5yijA6O7Wtks0SLeojmY8/zsNLMO8Mvl9FlYfHD6s255oN2MH9bdYu2wxXcUyKuRL0hK52CFgHC+0S+9SGl9LIE3sZZoH72KDNcM/oEvpnc+ejQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755302511; c=relaxed/simple; bh=tt2fnvxyKHuxMWduq2G5iWtwAxgOUA1tzVmzIKN+kzc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=QYbYmhhxXWRqlMM7djLCcFm3sCB/I/yOUPGMHAjeRgfcw9pSw7rf4skk5BFnslBMBulO0TugS0uCk/DT33DVHMDuhe3KcQvEf4dPJs4uPaNoSGIwKsfzrXC4rfYuOdrviGPeXh9E3jE6g5T2lDguV/+ckCDQw7bDfPg54h3tPo8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RfVvMfOG; 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="RfVvMfOG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00C22C4CEEB; Sat, 16 Aug 2025 00:01:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755302511; bh=tt2fnvxyKHuxMWduq2G5iWtwAxgOUA1tzVmzIKN+kzc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RfVvMfOG0b1QlhMLnLmblX46MZolGzZjvIs3TBKOhafZopSS0PhOLo13QQXH+vwf6 LV76Q3gdo2WypaqEUB4777jVJV2WXpaFcdf2/e6DYEyx63kv35q7OKgxo1L2aJ8P2r Grz2OFYCTC7QMt6oxr4LPRTSP67Zme20HH0HmFF1fhO/81KwGndvGKuKtMNG6HHgGg eSQBIoNtQL14j+3+nPHjR9OqpnEIa+qR8a0uLdoYHmggQtkbboKywiDuH8WpznnWth f77u9gyEwkVISoZJDwK/eDJ82g12NBxsCob6Yzf9cHwQMWfbuQjRr1VfYr07UD3Yph vzJvhbLHS4Y6Q== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 4D80BCE0B2D; Fri, 15 Aug 2025 17:01:50 -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 1/3] rcu: Document that rcu_barrier() hurries lazy callbacks Date: Fri, 15 Aug 2025 17:01:47 -0700 Message-Id: <20250816000149.2622447-1-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: References: 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