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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 38331C3E8C5 for ; Sun, 29 Nov 2020 03:32:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E691A206D8 for ; Sun, 29 Nov 2020 03:32:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="DtvCkB/w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725852AbgK2DcD (ORCPT ); Sat, 28 Nov 2020 22:32:03 -0500 Received: from mail.kernel.org ([198.145.29.99]:43844 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725616AbgK2DcD (ORCPT ); Sat, 28 Nov 2020 22:32:03 -0500 Received: from paulmck-ThinkPad-P72.home (50-39-104-11.bvtn.or.frontiernet.net [50.39.104.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 040952065C; Sun, 29 Nov 2020 03:31:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606620682; bh=crnvAF2Yn4eRKwDGF/AWw7xr+y5uJdddgUpRt9ux8Go=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=DtvCkB/wzOKBnkwfXJCfwgV5nIlA9wB446scBhdFKB7QQ6IVgnbejz/QAYF9xkk/w vTtwPPGfMxv7ESf/ULpOajRjbLsQkO8WtR7li/KArM9yVeQWb4kmEN8GPnu7YrdasJ k4gbheldFANYgpYdCJ0F36qYDy4M+1U1pzg6lug8= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id C14083522D27; Sat, 28 Nov 2020 19:31:21 -0800 (PST) Date: Sat, 28 Nov 2020 19:31:21 -0800 From: "Paul E. McKenney" To: Paul Gortmaker Cc: linux-doc@vger.kernel.org, Michael Opdenacker , Steven Rostedt Subject: Re: [PATCH v2] docs: fix typos and drop/fix dead links in RCU documentation Message-ID: <20201129033121.GZ1437@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20201128145538.69468-1-paul.gortmaker@windriver.com> <20201128203259.74063-1-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201128203259.74063-1-paul.gortmaker@windriver.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Sat, Nov 28, 2020 at 03:32:59PM -0500, Paul Gortmaker wrote: > It appears the Compaq link moved to a machine at HP for a while > after the merger of the two, but that doesn't work either. A search > of HP for "wiz_2637" (w and w/o html suffix) comes up empty. > > Since the references aren't critical to the documents we remove them. > > Also, the lkml.kernel.org/g links have been broken for ages, so replace > them with lore.kernel.org/r links - standardize on lore for all links too. > > Note that we put off fixing these 4y ago - presumably thinking that a > treewide fixup was pending. Probably safe to go fix the RCU ones now. > > https://lore.kernel.org/r/20160915144926.GD10850@linux.vnet.ibm.com/ > > Cc: Michael Opdenacker > Cc: Steven Rostedt > Cc: "Paul E. McKenney" > Signed-off-by: Paul Gortmaker Queued for further review, thank you! Thanx, Paul > --- > > [v2: 2nd dead Alpha link found; also fixup the lkml --> lore links.] > > .../RCU/Design/Requirements/Requirements.rst | 23 +++++++++---------- > Documentation/RCU/checklist.rst | 8 +++---- > 2 files changed, 14 insertions(+), 17 deletions(-) > > diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst > index 2dce79dd0eaa..4ff0f4506fbf 100644 > --- a/Documentation/RCU/Design/Requirements/Requirements.rst > +++ b/Documentation/RCU/Design/Requirements/Requirements.rst > @@ -321,11 +321,10 @@ do_something_gp_buggy() below: > 12 } > > However, this temptation must be resisted because there are a > -surprisingly large number of ways that the compiler (to say nothing of > -`DEC Alpha CPUs `__) > -can trip this code up. For but one example, if the compiler were short > -of registers, it might choose to refetch from ``gp`` rather than keeping > -a separate copy in ``p`` as follows: > +surprisingly large number of ways that the compiler (or weak ordering > +CPUs like the DEC Alpha) can trip this code up. For but one example, if > +the compiler were short of registers, it might choose to refetch from > +``gp`` rather than keeping a separate copy in ``p`` as follows: > > :: > > @@ -1183,7 +1182,7 @@ costs have plummeted. However, as I learned from Matt Mackall's > `bloatwatch `__ efforts, memory > footprint is critically important on single-CPU systems with > non-preemptible (``CONFIG_PREEMPT=n``) kernels, and thus `tiny > -RCU `__ > +RCU `__ > was born. Josh Triplett has since taken over the small-memory banner > with his `Linux kernel tinification `__ > project, which resulted in `SRCU <#Sleepable%20RCU>`__ becoming optional > @@ -1624,7 +1623,7 @@ against mishaps and misuse: > init_rcu_head() and cleaned up with destroy_rcu_head(). > Mathieu Desnoyers made me aware of this requirement, and also > supplied the needed > - `patch `__. > + `patch `__. > #. An infinite loop in an RCU read-side critical section will eventually > trigger an RCU CPU stall warning splat, with the duration of > “eventually” being controlled by the ``RCU_CPU_STALL_TIMEOUT`` > @@ -1716,7 +1715,7 @@ requires almost all of them be hidden behind a ``CONFIG_RCU_EXPERT`` > > This all should be quite obvious, but the fact remains that Linus > Torvalds recently had to > -`remind `__ > +`remind `__ > me of this requirement. > > Firmware Interface > @@ -1837,9 +1836,9 @@ NMI handlers. > > The name notwithstanding, some Linux-kernel architectures can have > nested NMIs, which RCU must handle correctly. Andy Lutomirski `surprised > -me `__ > +me `__ > with this requirement; he also kindly surprised me with `an > -algorithm `__ > +algorithm `__ > that meets this requirement. > > Furthermore, NMI handlers can be interrupted by what appear to RCU to be > @@ -2264,7 +2263,7 @@ more extreme measures. Returning to the ``page`` structure, the > ``rcu_head`` field shares storage with a great many other structures > that are used at various points in the corresponding page's lifetime. In > order to correctly resolve certain `race > -conditions `__, > +conditions `__, > the Linux kernel's memory-management subsystem needs a particular bit to > remain zero during all phases of grace-period processing, and that bit > happens to map to the bottom bit of the ``rcu_head`` structure's > @@ -2328,7 +2327,7 @@ preempted. This requirement made its presence known after users made it > clear that an earlier `real-time > patch `__ did not meet their needs, in > conjunction with some `RCU > -issues `__ > +issues `__ > encountered by a very early version of the -rt patchset. > > In addition, RCU must make do with a sub-100-microsecond real-time > diff --git a/Documentation/RCU/checklist.rst b/Documentation/RCU/checklist.rst > index bb7128eb322e..2d1dc1deffc9 100644 > --- a/Documentation/RCU/checklist.rst > +++ b/Documentation/RCU/checklist.rst > @@ -70,7 +70,7 @@ over a rather long period of time, but improvements are always welcome! > is less readable and prevents lockdep from detecting locking issues. > > Letting RCU-protected pointers "leak" out of an RCU read-side > - critical section is every bid as bad as letting them leak out > + critical section is every bit as bad as letting them leak out > from under a lock. Unless, of course, you have arranged some > other means of protection, such as a lock or a reference count > -before- letting them out of the RCU read-side critical section. > @@ -129,9 +129,7 @@ over a rather long period of time, but improvements are always welcome! > accesses. The rcu_dereference() primitive ensures that > the CPU picks up the pointer before it picks up the data > that the pointer points to. This really is necessary > - on Alpha CPUs. If you don't believe me, see: > - > - http://www.openvms.compaq.com/wizard/wiz_2637.html > + on Alpha CPUs. > > The rcu_dereference() primitive is also an excellent > documentation aid, letting the person reading the > @@ -216,7 +214,7 @@ over a rather long period of time, but improvements are always welcome! > 7. As of v4.20, a given kernel implements only one RCU flavor, > which is RCU-sched for PREEMPT=n and RCU-preempt for PREEMPT=y. > If the updater uses call_rcu() or synchronize_rcu(), > - then the corresponding readers my use rcu_read_lock() and > + then the corresponding readers may use rcu_read_lock() and > rcu_read_unlock(), rcu_read_lock_bh() and rcu_read_unlock_bh(), > or any pair of primitives that disables and re-enables preemption, > for example, rcu_read_lock_sched() and rcu_read_unlock_sched(). > -- > 2.17.1 >