On Mon, Nov 04, 2019 at 10:46:41PM +0530, Amol Grover wrote: > 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@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. > > 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. It is of course only polite to include the author of the previous patch on CC, both using the "Cc: Phong Tran <tranmanphong@xxxxxxxxx>" tag following your "Signed-off" by. Thanx, Paul > 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 > > >
