Message-ID: <20191104171641.GA15217@workstation-kernel-dev>
Date:   Mon, 4 Nov 2019 22:46:41 +0530
From:   Amol Grover <frextrite@...il.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Jonathan Corbet <corbet@....net>, rcu@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] Documentation: RCU: whatisRCU: Fix formatting for
 section 2

On Mon, Nov 04, 2019 at 07:03:28AM -0800, Paul E. McKenney wrote:
> On Mon, Nov 04, 2019 at 07:03:15PM +0530, Amol Grover wrote:
> > Convert RCU API method text to sub-headings and
> > add hyperlink and superscript to 2 literary notes
> > under rcu_dereference() section
> > 
> > Signed-off-by: Amol Grover <frextrite@...il.com>
> 
> Good stuff, but Phong Tran beat you to it.  If you are suggesting
> changes to that patch, please send a reply to her email, which
> may be found here:
> 
> https://lore.kernel.org/lkml/20191030233128.14997-1-tranmanphong@gmail.com/
> 
> There are several options for replying to this email listed at the
> bottom of that web page.
> 
> 							Thanx, Paul

Thank you Paul! And that is correct, I was suggesting changes to
that patch. However, since that patch was already integrated into
the `dev` branch, I mistakenly believed this patch could be sent
independently. Sorry for the trouble, I'll re-send the patch the
correct way.

Thank you
Amol

> 
> > ---
> >  Documentation/RCU/whatisRCU.rst | 34 +++++++++++++++++++++++++++------
> >  1 file changed, 28 insertions(+), 6 deletions(-)
> > 
> > diff --git a/Documentation/RCU/whatisRCU.rst b/Documentation/RCU/whatisRCU.rst
> > index ae40c8bcc56c..3cf6e17d0065 100644
> > --- a/Documentation/RCU/whatisRCU.rst
> > +++ b/Documentation/RCU/whatisRCU.rst
> > @@ -150,6 +150,7 @@ later.  See the kernel docbook documentation for more info, or look directly
> >  at the function header comments.
> >  
> >  rcu_read_lock()
> > +^^^^^^^^^^^^^^^
> >  
> >  	void rcu_read_lock(void);
> >  
> > @@ -164,6 +165,7 @@ rcu_read_lock()
> >  	longer-term references to data structures.
> >  
> >  rcu_read_unlock()
> > +^^^^^^^^^^^^^^^^^
> >  
> >  	void rcu_read_unlock(void);
> >  
> > @@ -172,6 +174,7 @@ rcu_read_unlock()
> >  	read-side critical sections may be nested and/or overlapping.
> >  
> >  synchronize_rcu()
> > +^^^^^^^^^^^^^^^^^
> >  
> >  	void synchronize_rcu(void);
> >  
> > @@ -225,6 +228,7 @@ synchronize_rcu()
> >  	checklist.txt for some approaches to limiting the update rate.
> >  
> >  rcu_assign_pointer()
> > +^^^^^^^^^^^^^^^^^^^^
> >  
> >  	void rcu_assign_pointer(p, typeof(p) v);
> >  
> > @@ -245,6 +249,7 @@ rcu_assign_pointer()
> >  	the _rcu list-manipulation primitives such as list_add_rcu().
> >  
> >  rcu_dereference()
> > +^^^^^^^^^^^^^^^^^
> >  
> >  	typeof(p) rcu_dereference(p);
> >  
> > @@ -279,8 +284,10 @@ rcu_dereference()
> >  	if an update happened while in the critical section, and incur
> >  	unnecessary overhead on Alpha CPUs.
> >  
> > +.. _back_to_1:
> > +
> >  	Note that the value returned by rcu_dereference() is valid
> > -	only within the enclosing RCU read-side critical section [1].
> > +	only within the enclosing RCU read-side critical section |cs_1|.
> >  	For example, the following is -not- legal::
> >  
> >  		rcu_read_lock();
> > @@ -298,15 +305,27 @@ rcu_dereference()
> >  	it was acquired is just as illegal as doing so with normal
> >  	locking.
> >  
> > +.. _back_to_2:
> > +
> >  	As with rcu_assign_pointer(), an important function of
> >  	rcu_dereference() is to document which pointers are protected by
> >  	RCU, in particular, flagging a pointer that is subject to changing
> >  	at any time, including immediately after the rcu_dereference().
> >  	And, again like rcu_assign_pointer(), rcu_dereference() is
> >  	typically used indirectly, via the _rcu list-manipulation
> > -	primitives, such as list_for_each_entry_rcu() [2].
> > +	primitives, such as list_for_each_entry_rcu() |entry_2|.
> > +
> > +.. |cs_1| raw:: html
> > +
> > +	<a href="#cs"><sup>[1]</sup></a>
> > +
> > +.. |entry_2| raw:: html
> >  
> > -	[1] The variant rcu_dereference_protected() can be used outside
> > +	<a href="#entry"><sup>[2]</sup></a>
> > +
> > +.. _cs:
> > +
> > +	\ :sup:`[1]`\  The variant rcu_dereference_protected() can be used outside
> >  	of an RCU read-side critical section as long as the usage is
> >  	protected by locks acquired by the update-side code.  This variant
> >  	avoids the lockdep warning that would happen when using (for
> > @@ -317,15 +336,18 @@ rcu_dereference()
> >  	a lockdep expression to indicate which locks must be acquired
> >  	by the caller. If the indicated protection is not provided,
> >  	a lockdep splat is emitted.  See Documentation/RCU/Design/Requirements/Requirements.rst
> > -	and the API's code comments for more details and example usage.
> > +	and the API's code comments for more details and example usage. :ref:`back <back_to_1>`
> > +
> > +
> > +.. _entry:
> >  
> > -	[2] If the list_for_each_entry_rcu() instance might be used by
> > +	\ :sup:`[2]`\  If the list_for_each_entry_rcu() instance might be used by
> >  	update-side code as well as by RCU readers, then an additional
> >  	lockdep expression can be added to its list of arguments.
> >  	For example, given an additional "lock_is_held(&mylock)" argument,
> >  	the RCU lockdep code would complain only if this instance was
> >  	invoked outside of an RCU read-side critical section and without
> > -	the protection of mylock.
> > +	the protection of mylock. :ref:`back <back_to_2>`
> >  
> >  The following diagram shows how each API communicates among the
> >  reader, updater, and reclaimer.
> > -- 
> > 2.20.1
> > 

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