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 X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8E1AC47257 for ; Mon, 4 May 2020 00:39:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC42820735 for ; Mon, 4 May 2020 00:39:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="c+gq2Csa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726889AbgEDAjQ (ORCPT ); Sun, 3 May 2020 20:39:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36336 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726809AbgEDAjP (ORCPT ); Sun, 3 May 2020 20:39:15 -0400 Received: from mail-qv1-xf42.google.com (mail-qv1-xf42.google.com [IPv6:2607:f8b0:4864:20::f42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F6A2C061A0E for ; Sun, 3 May 2020 17:39:15 -0700 (PDT) Received: by mail-qv1-xf42.google.com with SMTP id v10so7598625qvr.2 for ; Sun, 03 May 2020 17:39:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ZU2Jq3uSJpx5BEWiOvjjNcojy+e0VaV2eMdS/R2jofE=; b=c+gq2CsapviuzhbYBwhkWprA+wnrt9iSRNkzDjfsdr8klJwCw3lo12OdY8UGP61V/F JiDHdnEVsJ0gQ6cdTTMXkOUmiqr4kBOguFPxzqy9B1nDZWxLZ7koDCCAOMdc21tNq2Wm RSZDF167f03u58e+jXnybeFxUJXategn8dNOQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ZU2Jq3uSJpx5BEWiOvjjNcojy+e0VaV2eMdS/R2jofE=; b=NCh5Ofi03icHIsyVNZ2ubrNqKyW1Qrxudoqd4+nVBsjfFt1Z1rOEOhFpmNwXOf9Vyn YjiTr6ZTU007o7pksKmkL0n+mtYLxi7jndsbBpnK5FILecaQxyjhdPOcVAy86DqyAN5y FspwuKtIaScaqKvPEqc+/Dt8eZNuaVcmdhuPQqrpHvOF3vX4hAm9WKAU6Kjb1S0Dcii1 /KMJQtG0mEyx8iW8zDiLc6ZqQwHDefuLyKIBZfUpVJqX09r2+eRkKgmdKthdTS/alyQ9 XgE2FvAaADWjRA6mDClVhc9i/7rNwx+h1Ax5XLM3rBYJ+2w9+A9p7BLCRrRw88h4cgcx 4lJg== X-Gm-Message-State: AGi0PuaOTAgu73BohtDk9NFgwoQL/srfP+8KSH33iDkO1+bAbTZW3on2 340Tg37dJ4qrs+HLbE69NWqsFQ== X-Google-Smtp-Source: APiQypLdBBSYo8HhlYJeaV+F4IR7VDwMmFvV05Z+duvtwaqhe2u+oVt/G2F8/UroUd8NM8jj3B8V5Q== X-Received: by 2002:a0c:8222:: with SMTP id h31mr14223004qva.106.1588552754590; Sun, 03 May 2020 17:39:14 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id t67sm8801032qka.17.2020.05.03.17.39.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 03 May 2020 17:39:13 -0700 (PDT) Date: Sun, 3 May 2020 20:39:13 -0400 From: Joel Fernandes To: "Paul E. McKenney" Cc: "Uladzislau Rezki (Sony)" , LKML , linux-mm@kvack.org, Andrew Morton , "Theodore Y . Ts'o" , Matthew Wilcox , RCU , Oleksiy Avramchenko Subject: Re: [PATCH 03/24] rcu/tree: Use consistent style for comments Message-ID: <20200504003913.GE212435@google.com> References: <20200428205903.61704-1-urezki@gmail.com> <20200428205903.61704-4-urezki@gmail.com> <20200501190555.GB7560@paulmck-ThinkPad-P72> <20200503235213.GC197097@google.com> <20200504002656.GE2869@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200504002656.GE2869@paulmck-ThinkPad-P72> Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Sun, May 03, 2020 at 05:26:56PM -0700, Paul E. McKenney wrote: > On Sun, May 03, 2020 at 07:52:13PM -0400, Joel Fernandes wrote: > > On Fri, May 01, 2020 at 12:05:55PM -0700, Paul E. McKenney wrote: > > > On Tue, Apr 28, 2020 at 10:58:42PM +0200, Uladzislau Rezki (Sony) wrote: > > > > From: "Joel Fernandes (Google)" > > > > > > > > Simple clean up of comments in kfree_rcu() code to keep it consistent > > > > with majority of commenting styles. > > > > > > > > Reviewed-by: Uladzislau Rezki > > > > Signed-off-by: Joel Fernandes (Google) > > > > Signed-off-by: Uladzislau Rezki (Sony) > > > > > > Hmmm... > > > > > > Exactly why is three additional characters per line preferable? Or in > > > the case of block comments, either one or two additional lines, depending > > > on /* */ style? > > > > I prefer to keep the code consistent and then bulk convert it later. Its a > > bit ugly to read when its mixed up with "//" and "/* */" right now. We can > > convert it to // all at once later but until then it'll be good to keep it > > consistent in this file IMO. When I checked the kfree_rcu() code, it had more > > "/* */" than not, so this small change is less churn for now. > > Please just drop this patch along with the other "//"-to-"/* */" > regressions. Right now in your rcu/dev branch (without applying this series),in kfree_rcu_drain_unlock() and the functions before and after it, it is inconsistent. Also in kfree_call_rcu(), it is: // Queue the object but don't yet schedule the batch. if (debug_rcu_head_queue(head)) { // Probable double kfree_rcu(), just leak. WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n", __func__, head); goto unlock_return; } /* * Under high memory pressure GFP_NOWAIT can fail, * in that case the emergency path is maintained. */ > If you want to convert more comments to "//" within the confines of the > kfree_rcu() code, I am probably OK with that. But again, a big-bang > change of this sort often causes problems due to lots of potential > rebase/merge conflicts. Ok. Since this series touched kfree-related RCU code, converting all of the kfree-related RCU code to "//" is Ok with me. Just wanted to keep it consistent :) thanks, - Joel > > Thanx, Paul > > > thanks, > > > > - Joel > > > > > > > > I am (slowly) moving RCU to "//" for those reasons. ;-) > > > > > > Thanx, Paul > > > > > > > --- > > > > kernel/rcu/tree.c | 16 ++++++++-------- > > > > 1 file changed, 8 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > > > index cd61649e1b00..1487af8e11e8 100644 > > > > --- a/kernel/rcu/tree.c > > > > +++ b/kernel/rcu/tree.c > > > > @@ -3043,15 +3043,15 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp) > > > > static inline void kfree_rcu_drain_unlock(struct kfree_rcu_cpu *krcp, > > > > unsigned long flags) > > > > { > > > > - // Attempt to start a new batch. > > > > + /* Attempt to start a new batch. */ > > > > krcp->monitor_todo = false; > > > > if (queue_kfree_rcu_work(krcp)) { > > > > - // Success! Our job is done here. > > > > + /* Success! Our job is done here. */ > > > > raw_spin_unlock_irqrestore(&krcp->lock, flags); > > > > return; > > > > } > > > > > > > > - // Previous RCU batch still in progress, try again later. > > > > + /* Previous RCU batch still in progress, try again later. */ > > > > krcp->monitor_todo = true; > > > > schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); > > > > raw_spin_unlock_irqrestore(&krcp->lock, flags); > > > > @@ -3151,14 +3151,14 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > > > > unsigned long flags; > > > > struct kfree_rcu_cpu *krcp; > > > > > > > > - local_irq_save(flags); // For safely calling this_cpu_ptr(). > > > > + local_irq_save(flags); /* For safely calling this_cpu_ptr(). */ > > > > krcp = this_cpu_ptr(&krc); > > > > if (krcp->initialized) > > > > raw_spin_lock(&krcp->lock); > > > > > > > > - // Queue the object but don't yet schedule the batch. > > > > + /* Queue the object but don't yet schedule the batch. */ > > > > if (debug_rcu_head_queue(head)) { > > > > - // Probable double kfree_rcu(), just leak. > > > > + /* Probable double kfree_rcu(), just leak. */ > > > > WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n", > > > > __func__, head); > > > > goto unlock_return; > > > > @@ -3176,7 +3176,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > > > > > > > > WRITE_ONCE(krcp->count, krcp->count + 1); > > > > > > > > - // Set timer to drain after KFREE_DRAIN_JIFFIES. > > > > + /* Set timer to drain after KFREE_DRAIN_JIFFIES. */ > > > > if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING && > > > > !krcp->monitor_todo) { > > > > krcp->monitor_todo = true; > > > > @@ -3722,7 +3722,7 @@ int rcutree_offline_cpu(unsigned int cpu) > > > > > > > > rcutree_affinity_setting(cpu, cpu); > > > > > > > > - // nohz_full CPUs need the tick for stop-machine to work quickly > > > > + /* nohz_full CPUs need the tick for stop-machine to work quickly */ > > > > tick_dep_set(TICK_DEP_BIT_RCU); > > > > return 0; > > > > } > > > > -- > > > > 2.20.1 > > > >