[PATCH] Documentation: RCU: whatisRCU: Fix formatting for section 2

[Amol Grover]

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@xxxxxxxxx>
---
 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