Re: [PATCH v2] docs: fix typos and drop/fix dead links in RCU documentation

["Paul E. McKenney" <paulmck@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 <michael.opdenacker@free-electrons.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

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 <https://h71000.www7.hp.com/wizard/wiz_2637.html>`__)
> -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 <http://elinux.org/Linux_Tiny-FAQ>`__ efforts, memory
>  footprint is critically important on single-CPU systems with
>  non-preemptible (``CONFIG_PREEMPT=n``) kernels, and thus `tiny
> -RCU <https://lkml.kernel.org/g/20090113221724.GA15307@linux.vnet.ibm.com>`__
> +RCU <https://lore.kernel.org/r/20090113221724.GA15307@linux.vnet.ibm.com>`__
>  was born. Josh Triplett has since taken over the small-memory banner
>  with his `Linux kernel tinification <https://tiny.wiki.kernel.org/>`__
>  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 <https://lkml.kernel.org/g/20100319013024.GA28456@Krystal>`__.
> +   `patch <https://lore.kernel.org/r/20100319013024.GA28456@Krystal>`__.
>  #. 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 <https://lkml.kernel.org/g/CA+55aFy4wcCwaL4okTs8wXhGZ5h-ibecy_Meg9C4MNQrUnwMcg@mail.gmail.com>`__
> +`remind <https://lore.kernel.org/r/CA+55aFy4wcCwaL4okTs8wXhGZ5h-ibecy_Meg9C4MNQrUnwMcg@mail.gmail.com>`__
>  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 <https://lkml.kernel.org/r/CALCETrXLq1y7e_dKFPgou-FKHB6Pu-r8+t-6Ds+8=va7anBWDA@mail.gmail.com>`__
> +me <https://lore.kernel.org/r/CALCETrXLq1y7e_dKFPgou-FKHB6Pu-r8+t-6Ds+8=va7anBWDA@mail.gmail.com>`__
>  with this requirement; he also kindly surprised me with `an
> -algorithm <https://lkml.kernel.org/r/CALCETrXSY9JpW3uE6H8WYk81sg56qasA2aqmjMPsq5dOtzso=g@mail.gmail.com>`__
> +algorithm <https://lore.kernel.org/r/CALCETrXSY9JpW3uE6H8WYk81sg56qasA2aqmjMPsq5dOtzso=g@mail.gmail.com>`__
>  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 <https://lkml.kernel.org/g/1439976106-137226-1-git-send-email-kirill.shutemov@linux.intel.com>`__,
> +conditions <https://lore.kernel.org/r/1439976106-137226-1-git-send-email-kirill.shutemov@linux.intel.com>`__,
>  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 <https://lwn.net/Articles/107930/>`__ did not meet their needs, in
>  conjunction with some `RCU
> -issues <https://lkml.kernel.org/g/20050318002026.GA2693@us.ibm.com>`__
> +issues <https://lore.kernel.org/r/20050318002026.GA2693@us.ibm.com>`__
>  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
>