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@xxxxxxxxx> 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@xxxxxxxxx/ There are several options for replying to this email listed at the bottom of that web page. Thanx, Paul > --- > 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 >
