[Linux-kernel-mentees] [PATCH] Documentation: RCU: whatisRCU: Fix formatting for section 2

Tue Nov 5 07:41:22 UTC 2019

On Tue, Nov 05, 2019 at 08:08:50AM +0200, Jani Nikula wrote:
> On Mon, 04 Nov 2019, Amol Grover <frextrite at gmail.com> wrote:
> > On Mon, Nov 04, 2019 at 05:15:34PM +0200, Jani Nikula wrote:
> >> On Mon, 04 Nov 2019, Amol Grover <frextrite at gmail.com> 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 at gmail.com>
> >> > ---
> >> >  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
> >> 
> >> Please don't use raw. It's ugly and error prone. We have some raw output
> >> for latex, but this would be the first for html.
> >> 
> >> What are you trying to achieve?
> >
> > Hi Jani,
> > While going through the documentation I encountered a few footnotes (numbers
> > [1] and [2]) which referenced the actual footnote somewhere below the text.
> > They were particularly not straight-forward to find hence I decided to
> > link them to the footnote text which could be done using inline markup.
> > Then I tried to make them more appealing by converting to super-scripts
> > (the way they look like in books and websites). However, nested inline 
> > markup is not yet possible in reST hence I went with the html way to 
> > achieve the same. Too much?
> 
> I suggest you use rst footnote markup. It's less of an eye sore in the
> rst source, but provides you with the links in the generated output. And
> typically would be superscript. In particular "autonumber labels" might
> fit the bill. [1][2]
> 
> BR,
> Jani.
> 
> 
> [1] http://docutils.sourceforge.net/docs/user/rst/quickref.html#footnotes
> [2] http://docutils.sourceforge.net/docs/ref/rst/restructuredtext.html#footnotes
> 
> 
> >
> > Thank you
> > Amol
> >
> >> 
> >> BR,
> >> Jani.
> >> 
> >> > +
> >> > +	<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.
> >> 
> >> -- 
> >> Jani Nikula, Intel Open Source Graphics Center
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center

Thank you for the feedback Paul and Jani! Sent the updated
patch at
https://lore.kernel.org/lkml/20191105073340.GA3682@workstation-kernel-dev/
with the requested changes.

Thank you
Amol