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 38DEBC433FE for ; Wed, 23 Nov 2022 15:59:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237614AbiKWP7o (ORCPT ); Wed, 23 Nov 2022 10:59:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235918AbiKWP7d (ORCPT ); Wed, 23 Nov 2022 10:59:33 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CE8EDD; Wed, 23 Nov 2022 07:59:33 -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 dfw.source.kernel.org (Postfix) with ESMTPS id BB56361DDD; Wed, 23 Nov 2022 15:59:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A36D7C433C1; Wed, 23 Nov 2022 15:59:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669219172; bh=xhSayXw1inqZZFR8s8TjR7HOd4tlJGjeZ7YEdMkj0Dw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Y8XtedCI2cb2NetRpBy1LlZ+TWi4QP9EUWRkC2deGnsJYW9UVOjt80Is59hSqFyLY HH4bCYAqZt9gIh/1DGIasGWhgO5STPf/oEMiyJUZuSdRwDZitVJTLuOgYLYOvMI+2d gHejASlEU2w3FyAQI9lixHIJpbPDXs11ZRwgnbM4bjLErBTQtNxVMjIhUsoO0yipOb RxpdNqc3cOObreVzSFdGQtgQU6BpqzFPkb2UcmsUCCrVDZoFTCn7FIZbv3k++PpimE UTujas1rpDHzA0EhR1CaxDCrKZ+wLgd21dCuWtNNFXSTNOwHFBZBE6EIaNQZ22Sj0+ sSljr25NhDKQA== Date: Wed, 23 Nov 2022 16:59:29 +0100 From: Frederic Weisbecker To: "Paul E. McKenney" 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: <20221123155929.GB1387380@lothringen> References: <20221122010408.GA3799268@paulmck-ThinkPad-P17-Gen-1> <20221122010421.3799681-5-paulmck@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221122010421.3799681-5-paulmck@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > > 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 Thanks. > > rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rcl); > WRITE_ONCE(rdp->nocb_bypass_first, j); > -- > 2.31.1.189.g2e36527f23 >