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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14CEBC4332F for ; Wed, 23 Nov 2022 17:54:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239057AbiKWRyn (ORCPT ); Wed, 23 Nov 2022 12:54:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236601AbiKWRyl (ORCPT ); Wed, 23 Nov 2022 12:54:41 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6152E65844; Wed, 23 Nov 2022 09:54:40 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E55BBB82208; Wed, 23 Nov 2022 17:54:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97AA9C433D7; Wed, 23 Nov 2022 17:54:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669226077; bh=KojPnCJDd+viWW6lLyZAJlQQAA7kDDhcYbMJeadUl/g=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=ZmFzWMqQyUimMTw5jdhvuXaNi9STJVNZY0Dj3dlMyquHVUUkGbbMCY4ot4DNMsNqT PFmUbxfCqQIOf+slnTfIercvXQvZhn2v82VM+yFA25mLs63I9cB4itvtbZL4Ho+4EB RRBISd6ETV0iFXGXQGqmYcO67QR+QRjj+5+eIcXmbAZ0gNV/aZ0KDK1TXfdLEw67v6 eLTwtI9A6uwVrI73FKLibYsqMEdYH9Rv0OoTZcEPfkvOGsMI7oUrMLOtsx4/ma6ky6 gkck0ema33P83/BIt6BOqVGNcE2yMFaQOyEyt31ZrpxxJSaMOok7GX8cj9ous7Tj27 EYG6j/JywzdeA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 3313F5C0A3F; Wed, 23 Nov 2022 09:54:37 -0800 (PST) Date: Wed, 23 Nov 2022 09:54:37 -0800 From: "Paul E. McKenney" To: Frederic Weisbecker Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, "Joel Fernandes (Google)" Subject: Re: [PATCH v2 rcu 05/16] rcu: Refactor code a bit in rcu_nocb_do_flush_bypass() Message-ID: <20221123175437.GA4001@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20221122010408.GA3799268@paulmck-ThinkPad-P17-Gen-1> <20221122010421.3799681-5-paulmck@kernel.org> <20221123155929.GB1387380@lothringen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221123155929.GB1387380@lothringen> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 23, 2022 at 04:59:29PM +0100, Frederic Weisbecker wrote: > On Mon, Nov 21, 2022 at 05:04:10PM -0800, Paul E. McKenney wrote: > > From: "Joel Fernandes (Google)" > > > > This consolidates the code a bit and makes it cleaner. Functionally it > > is the same. > > > > Reported-by: Paul E. McKenney > > Signed-off-by: Joel Fernandes (Google) > > Signed-off-by: Paul E. McKenney > > --- > > kernel/rcu/tree_nocb.h | 17 +++++++++-------- > > 1 file changed, 9 insertions(+), 8 deletions(-) > > > > diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h > > index d6e4c076b0515..213daf81c057f 100644 > > --- a/kernel/rcu/tree_nocb.h > > +++ b/kernel/rcu/tree_nocb.h > > @@ -327,10 +327,11 @@ static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype, > > * > > * Note that this function always returns true if rhp is NULL. > > */ > > -static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp, > > +static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp_in, > > unsigned long j, bool lazy) > > { > > struct rcu_cblist rcl; > > + struct rcu_head *rhp = rhp_in; > > Why that intermediate rhp_in? To avoid modifying the formal parameter, should the original value prove useful, for example, for tracing or debugging. > > WARN_ON_ONCE(!rcu_rdp_is_offloaded(rdp)); > > rcu_lockdep_assert_cblist_protected(rdp); > > @@ -345,16 +346,16 @@ static bool rcu_nocb_do_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp, > > > > /* > > * If the new CB requested was a lazy one, queue it onto the main > > - * ->cblist so we can take advantage of a sooner grade period. > > + * ->cblist so that we can take advantage of the grace-period that will > > + * happen regardless. But queue it onto the bypass list first so that > > + * the lazy CB is ordered with the existing CBs in the bypass list. > > */ > > if (lazy && rhp) { > > - rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, NULL); > > - rcu_cblist_enqueue(&rcl, rhp); > > - WRITE_ONCE(rdp->lazy_len, 0); > > - } else { > > - rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp); > > - WRITE_ONCE(rdp->lazy_len, 0); > > + rcu_cblist_enqueue(&rdp->nocb_bypass, rhp); > > + rhp = NULL; > > } > > + rcu_cblist_flush_enqueue(&rcl, &rdp->nocb_bypass, rhp); > > + WRITE_ONCE(rdp->lazy_len, 0); > > Reviewed-by: Frederic Weisbecker Thank you! I will apply this on my next rebase. Thanx, Paul > Thanks. > > > > > rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rcl); > > WRITE_ONCE(rdp->nocb_bypass_first, j); > > -- > > 2.31.1.189.g2e36527f23 > >